Ehlers-Danlos syndrome

Ehlers-Danlos Syndrome

Definition

The Ehlers-Danlos syndromes (EDS) refer to a group of inherited disorders that affect collagen structure and function. Genetic abnormalities in the manufacturing of collagen within the body affect connective tissues, causing them to be abnormally weak.

Description

Collagen is a strong, fibrous protein that lends strength and elasticity to connective tissues such as the skin, tendons, organ walls, cartilage, and blood vessels. Each of these connective tissues requires collagen tailored to meet its specific purposes. The many roles of collagen are reflected in the number of genes dedicated to its production. There are at least 28 genes in humans that encode at least 19 different types of collagen. Mutations in these genes can affect basic construction as well as the fine-tuned processing of the collagen.EDS was originally described by Dr. Van Meekeren in 1682. Dr. Ehlers and Dr. Danlos further characterized the disease in 1901 and 1908, respectively. Today, according to the Ehlers-Danlos National Foundation, one in 5,000 to one in 10,000 people are affected by some form of EDS.EDS is a group of genetic disorders that usually affects the skin, ligaments, joints, and blood vessels. Classification of EDS types was revised in 1997. The new classification involves categorizing the different forms of EDS into six major sub-types, including classical, hypermobility, vascular, kyphoscoliosis, arthrochalasia, and dermatosparaxis, and a collection of rare or poorly defined varieties. This new classification is simpler and based more on descriptions of the actual symptoms.

Classical type

Under the old classification system, EDS classical type was divided into two separate types: type I and type II. The major symptoms involved in EDS classical type are the skin and joints. The skin has a smooth, velvety texture and bruises easily. Affected individuals typically have extensive scaring, particularly at the knees, elbows, forehead, and chin. The joints are hyperextensible, giving a tendency towards dislocation of the hip, shoulder, elbow, knee, or clavicle. Due to decreased muscle tone, affected infants may experience a delay in reaching motor milestones. Children may have a tendency to develop hernias or other organ shifts within the abdomen. Sprains and partial or complete joint dilocations are also common. Symptoms can range from mild to severe. EDS classical type is inherited in an autosomal dominant manner.There are three major clinical diagnostic criteria for EDS classical type. These include skin hyperextensibility, unusually wide scars, and joint hypermobility. At this time there is no definitive test for the diagnosis of classical EDS. Both DNA and biochemical studies have been used to help identify affected individuals. In some cases, a skin biopsy has been found to be useful in confirming a diagnosis. Unfortunately, these tests are not sensitive enough to identify all individuals with classical EDS. If there are multiple affected individuals in a family, it may be possible to perform prenatal diagnosis using a DNA information technique known as a linkage study.

Hypermobility type

Excessively loose joints are the hallmark of this EDS type, formerly known as EDS type III. Both large joints, such as the elbows and knees, and small joints, such as toes and fingers, are affected. Partial and total joint dislocations are common, and particularly involve the jaw, knee, and shoulder. Many individuals experience chronic limb and joint pain, although x rays of these joints appear normal. The skin may also bruise easily. Osteoarthritis is a common occurrence in adults. EDS hypermobility type is inherited in an autosomal dominant manner.There are two major clinical diagnostic criteria for EDS hypermobility type. These include skin involvement (either hyperextensible skin or smooth and velvety skin) and generalized joint hypermobility. At this time there is no test for this form of EDS.

Vascular type

Formerly called EDS type IV, EDS vascular type is the most severe form. The connective tissue in the intestines, arteries, uterus, and other hollow organs may be unusually weak, leading to organ or blood vessel rupture. Such ruptures are most likely between ages 20 and 40, although they can occur any time, and may be life-threatening.There is a classic facial appearance associated with EDS vascular type. Affected individuals tend to have large eyes, a thin pinched nose, thin lips, and a slim body. The skin is thin and translucent, with veins dramatically visible, particularly across the chest.The large joints have normal stability, but small joints in the hands and feet are loose, showing hyperextensibility. The skin bruises easily. Other complications may include collapsed lungs, premature aging of the skin on the hands and feet, and ruptured arteries and veins. After surgery there tends to be poor wound healing, a complication that tends to be frequent and severe. Pregnancy also carries the risk complications. During and after pregnancy there is an increased risk of the uterus rupturing and of arterial bleeding. Due to the severe complications associated with EDS type IV, death usually occurs before the fifth decade. A study of 419 individuals with EDS vascular type, completed in 2000, found that the median survival rate was 48 years, with a range of six to 73 years. EDS vascular type is inherited in an autosomal dominant manner.There are four major clinical diagnostic criteria for EDS vascular type. These include thin translucent skin, arterial/intestinal/uterine fragility or rupture, extensive bruising, and characteristic facial appearance. EDS vascular type is caused by a change in the gene COL3A1, which codes for one of the collagen chains used to build Collage type III. Laboratory testing is available for this form of EDS. A skin biopsy may be used to demonstrate the structurally abnormal collagen. This type of biochemical test identifies more than 95% of individuals with EDS vascular type. Laboratory testing is recommended for individuals with two or more of the major criteria.DNA analysis may als be used to identify the change within the COL3A1 gene. This information may be helpful for genetic counseling purposes. Prenatal testing is available for pregnancies in which an affected parent has been identified and their DNA mutation is known or their biochemical defect has been demonstrated.

Kyphoscoliosis type

The major symptoms of kyphoscoliosis type, formerly called EDS type VI, are general joint looseness. At birth, the muscle tone is poor, and motor skill development is subsequently delayed. Also, infants with this type of EDS have an abnormal curvature of the spine (scoliosis). The scoliosis becomes progressively worse with age, with affected individuals usually unable to walk by age 20. The eyes and skin are fragile and easily damaged, and blood vessel involvement is a possibility. The bones may also be affected as demonstrated by a decrease in bone mass. Kyphoscoliosis type is inherited in an autosomal recessive manner.There are four major clinical diagnostic criteria for EDS kyphoscoliosis type. These include generaly loose joints, low muscle tone at birth, scoliosis at birth (which worsens with age), and a fragility of the eyes, which may give the white area of the eye a blue tint or cause the eye to rupture. This form of EDS is caused by a change in the PLOD gene on chromosome 1, which encodes the enzyme lysyl hydroxylase. A laboratory test is available in which urinary hydroxylysyl pryridinoline is measured. This test, performed on urine is extremely senstive and specific for EDS kyphoscolios type. Laboratory testing is recommended for infants with three or more of the major diagnostic criteria.Prenatal testing is available if a pregnancy is known to be at risk and an identified affected family member has had positive laboratory testing. An amniocentesis may be performed in which fetal cells are removed from the amniotic fluid and enzyme activity is measured.

Arthrochalasia type

Dislocation of the hip joint typically accompanies arthrochalasia type EDS, formerly called EDS type VIIB. Other joints are also unusually loose, leading to recurrent partial and total dislocations. The skin has a high degree of stretchability and bruises easily. Individuals with this type of EDS may also experience mildly diminished bone mass, scoliosis, and poor muscle tone. Arthrochalasia type is inherited in an autosomal dominant manner.There are two major clinical diagnostic criteria for EDS arthrochalasia type. These include sever generalized joing hypermobility and bilateral hip dislocation present at birth. This form of EDS is caused by a change in either of two components of Collage type I, called proa1(I) type A and proa2(I) type B. A skin biopsy may be preformed to demonstrate an abnormality in either components. Direct DNA testing is also available.

Dermatosparaxis type

Individuals with this type of EDS, once called type VIIC, have extremely fragile skin that bruises easily but does not scar excessively. The skin is soft and may sag, leading to an aged appearance even in young adults. Individuals may also experience hernias. Dermatosparaxis type is inherited in an autosomal recessive manner.There are two major clinical diagnostic criteria for EDS dematosparaxis type. These include severe skin fragility and sagging or aged appearing skin. This form of EDS is caused by a change in the enzyme called procollagen I N-terminal peptidase. A skin biopsy may be preformed for a definitive diagnosis of Dermatosparaxis type.

Other types

There are several other forms of EDS that have not been as clearly defined as the aforementioned types. Forms of EDS within this category may present with soft, mildly stretchable skin, shortened bones, chronic diarrhea, joint hypermobility and dislocation, bladder rupture, or poor wound healing. Inheritance patterns within this group include X-linked recessive, autosomal dominant, and autosomal recessive.

Causes and symptoms

There are numerous types of EDS, all caused by changes in one of several genes. The manner in which EDS is inherited depends on the specific gene involved. There are three patterns of inheritance for EDS: autosomal dominant, autosomal recessive, and X-linked (extremely rare).Chromosomes are made up of hundreds of small units known as genes, which contain the genetic material necessary for an individual to develop and function. Humans have 46 chromosomes, which are matched into 23 pairs. Because chromosomes are inherited in pairs, each individual receives two copies of each chromosome and likewise two copies of each gene.Changes or mutations in genes can cause genetic diseases in several different ways, many of which are represented within the spectrum of EDS. In autosomal dominant EDS, only one copy of a specific gene must be changed for a person to have EDS. In autosomal recessive EDS, both copies of a specific gene must be changed for a person to have EDS. If only one copy of an autosomal recessive EDS gene is changed the person is referred to as a carrier, meaning they do not have any of the signs or symptoms of the disease itself, but carry the possibility of passing on the disorder to a future child. In X-linked EDS a specific gene on the X chromosome must be changed. However, this affects males and females differently because males and females have a different number of X chromosomes.The few X-linked forms of EDS fall under the category of X-linked recessive. As with autosomal recessive, this implies that both copies of a specific gene must be changed for a person to be affected. However, because males only have one X-chromosome, they are affected if an X-linked recessive EDS gene is changed on their single X-chromosome. That is, they are affected even though they have only one changed copy. On the other hand, that same gene must be changed on both of the X-chromosomes in a female for her to be affected.Although there is much information regarding the changes in genes that cause EDS and their various inheritance patterns, the exact gene mutation for all types of EDS is not known.

Diagnosis

Clinical symptoms such as extreme joint looseness and unusual skin qualities, along with family history, can lead to a diagnosis of EDS. Specific tests, such as skin biopsies are available for diagnosis of certain types of EDS, including vascular, arthrochalasia, and dermatosparaxis types. A skin biopsy involves removing a small sample of skin and examining its microscopic structure. A urine test is available for the Kyphoscoliosis type.Management of all types of EDS may include genetic counseling to help the affected individual and their family understand the disorder and its impact on other family members and future children.If a couple has had a child diagnosed with EDS the chance that they will have another child with the same disorder depends on with what form of EDS the child has been diagnosed and if either parent is affected by the same disease or not.Individuals diagnosed with an autosomal dominant form of EDS have a 50% chance of passing the same disorder on to a child in each pregnancy. Individuals diagnosed with an autosomal recessive form of EDS have an extremely low risk of having a child with the same disorder.X-linked recessive EDS is accompanied by a slightly more complicated pattern of inheritance. If a father with an X-linked recessive form of EDS passes a copy of his X chromosome to his children, the sons will be unaffected and the daughters will be carriers. If a mother is a carrier for an X-linked recessive form of EDS, she may have affected or unaffected sons, or carrier or unaffected daughters, depending on the second sex chromosome inherited from the father.Prenatal diagnosis is available for specific forms of EDS, including kyphosocliosis type and vascular type. However, prenatal testing is only a possibility in these types if the underlying defect has been found in another family member.

Treatment

Medical therapy relies on managing symptoms and trying to prevent further complications. There is no cure for EDS.Braces may be prescribed to stabilize joints, although surgery is sometimes necessary to repair joint damage caused by repeated dislocations. Physical therapy teaches individuals how to strengthen muscles around joints and may help to prevent or limit damage. Elective surgery is discouraged due to the high possibility of complications.

Alternative treatment

There are anecdotal reports that large daily doses 0.04-0.14 oz (1-4 g) of vitamin C may help decrease bruising and aid in wound healing. Constitutional homeopathic treatment may be helpful in maintaining optimal health in persons with a diagnosis of EDS. An individual with EDS should discuss these types of therapies with their doctor before beginning them on their own. Therapy that does not require medical consultation involves protecting the skin with sunscreen and avoiding activities that place stress on the joints.

Prognosis

The outlook for individuals with EDS depends on the type of EDS with which they have been diagnosed. Symptoms vary in severity, even within one sub-type, and the frequency of complications changes on an individual basis. Some individuals have negligible symptoms while others are severely restricted in their daily life. Extreme joint instability and scoliosis may limit a person's mobility. Most individuals will have a normal lifespan. However, those with blood vessel involvement, particularly those with EDS vascular type, have an increased risk of fatal complications.EDS is a lifelong condition. Affected individuals may face social obstacles related to their disease on a daily basis. Some people with EDS have reported living with fears of significant and painful skin ruptures, becoming pregnant (especially those with EDS vascular type), their condition worsening, becoming unemployed due to physical and emotional burdens, and social stigmatization in general.Constant bruises, skin wounds, and trips to the hospital take their toll on both affected children and their parents. Prior to diagnosis parents of children with EDS have found themselves under suspicion of child abuse.Some people with EDS are not diagnosed until well into adulthood and, in the case of EDS vascular type, occasionally not until after death due to complications of the disorder. Not only may the diagnosis itself be devastating to the family, but in many cases other family members find out for the first time they are at risk for being affected.Although individuals with EDS face significant challenges, it is important to remember that each person is unique with their own distinguished qualities and potential. Persons with EDS go on to have families, to have careers, and to be accomplished citizens, surmounting the challenges of their disease.

Key terms

Arthrochalasia — Excessive loosness of the joints.Blood vessels — General term for arteries, veins, and capillaries that transport blood throughout the body.Cartilage — Supportive connective tissue that cushions bone at the joints or which connects muscle to bone.Collagen — The main supportive protein of cartilage, connective tissue, tendon, skin, and bone.Connective tissue — A group of tissues responsible for support throughout the body; includes cartilage, bone, fat, tissue underlying skin, and tissues that support organs, blood vessels, and nerves throughout the body.Dermatosparaxis — Skin fragility caused by abnormal collagen.Hernia — A rupture in the wall of a body cavity, through which an organ may protrude.Homeopathic — A holistic and natural approach to healthcare.Hyperextensibility — The ability to extend a joint beyond the normal range.Hypermobility — Unusual flexibility of the joints, allowing them to be bent or moved beyond their normal range of motion.Joint dislocation — The displacement of a bone.Kyphoscoliosis — Abnormal front-to-back and side-to-side curvature of the spine.Ligament — A type of connective tissue that connects bones or cartilage and provides support and strength to joints.Osteoarthritis — A degenerative joint disease that causes pain and stiffness.Scoliosis — An abnormal, side-to-side curvature of the spine.Tendon — A strong connective tissue that connects muscle to bone.Uterus — A muscular, hollow organ of the female reproductive tract. The uterus contains and nourishes the embryo and fetus from the time the fertilized egg is implanted until birth.Vascular — Having to do with blood vessels.

Resources

Periodicals

"Clinical and Genetic Features of Ehlers-DanlosSyndrome Type IV, the Vascular Type." The New England Journal of Medicine 342, no. 10 (2000)."Living a Restricted Life with Ehlers-DanlosSyndrome." International Journal of Nursing Studies 37 (2000): 111-118.

Organizations

Ehlers-Danlos Support Group-UK. PO Box 335, Farnham, Surrey, GU10 1XJ. UK 01252 690 940. http://www.atv.ndirect.co.uk.Elhers-Danlos National Foundation. 6399 Wilshire Blvd., Ste 203, Los Angeles, CA 90048 (323) 651-3038. Fax: (323) 651-1366. http://www.ednf.org.

Other

GeneClinics. http://www.geneclinics.org.

cutis

[ku´tis] skin.cutis anseri´na goose flesh.cutis hyperelas´tica Ehlers-Danlos syndrome.cutis lax´a a group of connective tissue disorders in which the skin hangs in loose pendulous folds, believed to be associated with decreased elastic tissue formation as well as an abnormality in elastin formation, and usually occurring as a hereditary disorder and occasionally in an acquired form.

Ehl·ers-Dan·los syn·drome (EDS),

(ā'lĕrz dahn-los'), a group of connective tissue disorders characterized by hyperelasticity and fragility of the skin, hypermobility of the joints, and fragility of the cutaneous blood vessels and sometimes large arteries due to deficient quality or quantity of collagen; the most common types are inherited as autosomal dominant, caused by mutation in one of the following genes: the collagen V alpha-1 gene (COL5A1) on chromosome 9q or the collagen V alpha-2 gene (COL5A2) on 2q or COL3A1 gene on 2q.

Ehl·ers-Dan·los syn·drome

(ā'lerz dahn'lōs sin'drōm) An inherited disorder of connective tissue characterized by fragile hyperelastic skin and hypermobility of the joints. At least 14 variant forms have been identified and named.

Ehlers-Danlos syndrome

A genetic disorder in which the skin is abnormally elastic so that it may be greatly stretched. It is, however, unduly fragile and gapes widely when wounded. Joints are also unusually extensible. The condition is due to a widespread defect of polymerization of the protein collagen-one of the basic constructional materials of the body. (Edvard Ehlers, German dermatologist 1863–1937 and Henri Alexandre Danlos, French dermatologist, 1844–1932).

Ehlers,

Edvard L., Danish dermatologist, 1863-1937. Ehlers-Danlos syndrome - a group of inherited generalized connective tissue diseases. Synonym(s): Meekeren-Ehlers-Danlos syndrome

Danlos,

Henri-Alexander, French dermatologist, 1844-1912. Danlos phenomenonDanlos syndromeEhlers-Danlos syndrome - see under Ehlers

Meekeren,

Job van, Dutch surgeon, 1611-1666. Meekeren-Ehlers-Danlos syndrome - Synonym(s): Ehlers-Danlos syndrome

Ehl·ers-Dan·los syn·drome

(ā'lerz dahn'lōs sin'drōm) Connective tissue disorders characterized by hyperelasticity and fragility of skin, hypermobility of joints, and fragility of cutaneous blood vessels.

单词	ehlers-danlos syndrome
释义	DictionarySeesyndromeEncyclopediaSeecutis Ehlers-Danlos syndrome Ehlers-Danlos Syndrome Definition The Ehlers-Danlos syndromes (EDS) refer to a group of inherited disorders that affect collagen structure and function. Genetic abnormalities in the manufacturing of collagen within the body affect connective tissues, causing them to be abnormally weak. Description Collagen is a strong, fibrous protein that lends strength and elasticity to connective tissues such as the skin, tendons, organ walls, cartilage, and blood vessels. Each of these connective tissues requires collagen tailored to meet its specific purposes. The many roles of collagen are reflected in the number of genes dedicated to its production. There are at least 28 genes in humans that encode at least 19 different types of collagen. Mutations in these genes can affect basic construction as well as the fine-tuned processing of the collagen.EDS was originally described by Dr. Van Meekeren in 1682. Dr. Ehlers and Dr. Danlos further characterized the disease in 1901 and 1908, respectively. Today, according to the Ehlers-Danlos National Foundation, one in 5,000 to one in 10,000 people are affected by some form of EDS.EDS is a group of genetic disorders that usually affects the skin, ligaments, joints, and blood vessels. Classification of EDS types was revised in 1997. The new classification involves categorizing the different forms of EDS into six major sub-types, including classical, hypermobility, vascular, kyphoscoliosis, arthrochalasia, and dermatosparaxis, and a collection of rare or poorly defined varieties. This new classification is simpler and based more on descriptions of the actual symptoms. Classical type Under the old classification system, EDS classical type was divided into two separate types: type I and type II. The major symptoms involved in EDS classical type are the skin and joints. The skin has a smooth, velvety texture and bruises easily. Affected individuals typically have extensive scaring, particularly at the knees, elbows, forehead, and chin. The joints are hyperextensible, giving a tendency towards dislocation of the hip, shoulder, elbow, knee, or clavicle. Due to decreased muscle tone, affected infants may experience a delay in reaching motor milestones. Children may have a tendency to develop hernias or other organ shifts within the abdomen. Sprains and partial or complete joint dilocations are also common. Symptoms can range from mild to severe. EDS classical type is inherited in an autosomal dominant manner.There are three major clinical diagnostic criteria for EDS classical type. These include skin hyperextensibility, unusually wide scars, and joint hypermobility. At this time there is no definitive test for the diagnosis of classical EDS. Both DNA and biochemical studies have been used to help identify affected individuals. In some cases, a skin biopsy has been found to be useful in confirming a diagnosis. Unfortunately, these tests are not sensitive enough to identify all individuals with classical EDS. If there are multiple affected individuals in a family, it may be possible to perform prenatal diagnosis using a DNA information technique known as a linkage study. Hypermobility type Excessively loose joints are the hallmark of this EDS type, formerly known as EDS type III. Both large joints, such as the elbows and knees, and small joints, such as toes and fingers, are affected. Partial and total joint dislocations are common, and particularly involve the jaw, knee, and shoulder. Many individuals experience chronic limb and joint pain, although x rays of these joints appear normal. The skin may also bruise easily. Osteoarthritis is a common occurrence in adults. EDS hypermobility type is inherited in an autosomal dominant manner.There are two major clinical diagnostic criteria for EDS hypermobility type. These include skin involvement (either hyperextensible skin or smooth and velvety skin) and generalized joint hypermobility. At this time there is no test for this form of EDS. Vascular type Formerly called EDS type IV, EDS vascular type is the most severe form. The connective tissue in the intestines, arteries, uterus, and other hollow organs may be unusually weak, leading to organ or blood vessel rupture. Such ruptures are most likely between ages 20 and 40, although they can occur any time, and may be life-threatening.There is a classic facial appearance associated with EDS vascular type. Affected individuals tend to have large eyes, a thin pinched nose, thin lips, and a slim body. The skin is thin and translucent, with veins dramatically visible, particularly across the chest.The large joints have normal stability, but small joints in the hands and feet are loose, showing hyperextensibility. The skin bruises easily. Other complications may include collapsed lungs, premature aging of the skin on the hands and feet, and ruptured arteries and veins. After surgery there tends to be poor wound healing, a complication that tends to be frequent and severe. Pregnancy also carries the risk complications. During and after pregnancy there is an increased risk of the uterus rupturing and of arterial bleeding. Due to the severe complications associated with EDS type IV, death usually occurs before the fifth decade. A study of 419 individuals with EDS vascular type, completed in 2000, found that the median survival rate was 48 years, with a range of six to 73 years. EDS vascular type is inherited in an autosomal dominant manner.There are four major clinical diagnostic criteria for EDS vascular type. These include thin translucent skin, arterial/intestinal/uterine fragility or rupture, extensive bruising, and characteristic facial appearance. EDS vascular type is caused by a change in the gene COL3A1, which codes for one of the collagen chains used to build Collage type III. Laboratory testing is available for this form of EDS. A skin biopsy may be used to demonstrate the structurally abnormal collagen. This type of biochemical test identifies more than 95% of individuals with EDS vascular type. Laboratory testing is recommended for individuals with two or more of the major criteria.DNA analysis may als be used to identify the change within the COL3A1 gene. This information may be helpful for genetic counseling purposes. Prenatal testing is available for pregnancies in which an affected parent has been identified and their DNA mutation is known or their biochemical defect has been demonstrated. Kyphoscoliosis type The major symptoms of kyphoscoliosis type, formerly called EDS type VI, are general joint looseness. At birth, the muscle tone is poor, and motor skill development is subsequently delayed. Also, infants with this type of EDS have an abnormal curvature of the spine (scoliosis). The scoliosis becomes progressively worse with age, with affected individuals usually unable to walk by age 20. The eyes and skin are fragile and easily damaged, and blood vessel involvement is a possibility. The bones may also be affected as demonstrated by a decrease in bone mass. Kyphoscoliosis type is inherited in an autosomal recessive manner.There are four major clinical diagnostic criteria for EDS kyphoscoliosis type. These include generaly loose joints, low muscle tone at birth, scoliosis at birth (which worsens with age), and a fragility of the eyes, which may give the white area of the eye a blue tint or cause the eye to rupture. This form of EDS is caused by a change in the PLOD gene on chromosome 1, which encodes the enzyme lysyl hydroxylase. A laboratory test is available in which urinary hydroxylysyl pryridinoline is measured. This test, performed on urine is extremely senstive and specific for EDS kyphoscolios type. Laboratory testing is recommended for infants with three or more of the major diagnostic criteria.Prenatal testing is available if a pregnancy is known to be at risk and an identified affected family member has had positive laboratory testing. An amniocentesis may be performed in which fetal cells are removed from the amniotic fluid and enzyme activity is measured. Arthrochalasia type Dislocation of the hip joint typically accompanies arthrochalasia type EDS, formerly called EDS type VIIB. Other joints are also unusually loose, leading to recurrent partial and total dislocations. The skin has a high degree of stretchability and bruises easily. Individuals with this type of EDS may also experience mildly diminished bone mass, scoliosis, and poor muscle tone. Arthrochalasia type is inherited in an autosomal dominant manner.There are two major clinical diagnostic criteria for EDS arthrochalasia type. These include sever generalized joing hypermobility and bilateral hip dislocation present at birth. This form of EDS is caused by a change in either of two components of Collage type I, called proa1(I) type A and proa2(I) type B. A skin biopsy may be preformed to demonstrate an abnormality in either components. Direct DNA testing is also available. Dermatosparaxis type Individuals with this type of EDS, once called type VIIC, have extremely fragile skin that bruises easily but does not scar excessively. The skin is soft and may sag, leading to an aged appearance even in young adults. Individuals may also experience hernias. Dermatosparaxis type is inherited in an autosomal recessive manner.There are two major clinical diagnostic criteria for EDS dematosparaxis type. These include severe skin fragility and sagging or aged appearing skin. This form of EDS is caused by a change in the enzyme called procollagen I N-terminal peptidase. A skin biopsy may be preformed for a definitive diagnosis of Dermatosparaxis type. Other types There are several other forms of EDS that have not been as clearly defined as the aforementioned types. Forms of EDS within this category may present with soft, mildly stretchable skin, shortened bones, chronic diarrhea, joint hypermobility and dislocation, bladder rupture, or poor wound healing. Inheritance patterns within this group include X-linked recessive, autosomal dominant, and autosomal recessive. Causes and symptoms There are numerous types of EDS, all caused by changes in one of several genes. The manner in which EDS is inherited depends on the specific gene involved. There are three patterns of inheritance for EDS: autosomal dominant, autosomal recessive, and X-linked (extremely rare).Chromosomes are made up of hundreds of small units known as genes, which contain the genetic material necessary for an individual to develop and function. Humans have 46 chromosomes, which are matched into 23 pairs. Because chromosomes are inherited in pairs, each individual receives two copies of each chromosome and likewise two copies of each gene.Changes or mutations in genes can cause genetic diseases in several different ways, many of which are represented within the spectrum of EDS. In autosomal dominant EDS, only one copy of a specific gene must be changed for a person to have EDS. In autosomal recessive EDS, both copies of a specific gene must be changed for a person to have EDS. If only one copy of an autosomal recessive EDS gene is changed the person is referred to as a carrier, meaning they do not have any of the signs or symptoms of the disease itself, but carry the possibility of passing on the disorder to a future child. In X-linked EDS a specific gene on the X chromosome must be changed. However, this affects males and females differently because males and females have a different number of X chromosomes.The few X-linked forms of EDS fall under the category of X-linked recessive. As with autosomal recessive, this implies that both copies of a specific gene must be changed for a person to be affected. However, because males only have one X-chromosome, they are affected if an X-linked recessive EDS gene is changed on their single X-chromosome. That is, they are affected even though they have only one changed copy. On the other hand, that same gene must be changed on both of the X-chromosomes in a female for her to be affected.Although there is much information regarding the changes in genes that cause EDS and their various inheritance patterns, the exact gene mutation for all types of EDS is not known. Diagnosis Clinical symptoms such as extreme joint looseness and unusual skin qualities, along with family history, can lead to a diagnosis of EDS. Specific tests, such as skin biopsies are available for diagnosis of certain types of EDS, including vascular, arthrochalasia, and dermatosparaxis types. A skin biopsy involves removing a small sample of skin and examining its microscopic structure. A urine test is available for the Kyphoscoliosis type.Management of all types of EDS may include genetic counseling to help the affected individual and their family understand the disorder and its impact on other family members and future children.If a couple has had a child diagnosed with EDS the chance that they will have another child with the same disorder depends on with what form of EDS the child has been diagnosed and if either parent is affected by the same disease or not.Individuals diagnosed with an autosomal dominant form of EDS have a 50% chance of passing the same disorder on to a child in each pregnancy. Individuals diagnosed with an autosomal recessive form of EDS have an extremely low risk of having a child with the same disorder.X-linked recessive EDS is accompanied by a slightly more complicated pattern of inheritance. If a father with an X-linked recessive form of EDS passes a copy of his X chromosome to his children, the sons will be unaffected and the daughters will be carriers. If a mother is a carrier for an X-linked recessive form of EDS, she may have affected or unaffected sons, or carrier or unaffected daughters, depending on the second sex chromosome inherited from the father.Prenatal diagnosis is available for specific forms of EDS, including kyphosocliosis type and vascular type. However, prenatal testing is only a possibility in these types if the underlying defect has been found in another family member. Treatment Medical therapy relies on managing symptoms and trying to prevent further complications. There is no cure for EDS.Braces may be prescribed to stabilize joints, although surgery is sometimes necessary to repair joint damage caused by repeated dislocations. Physical therapy teaches individuals how to strengthen muscles around joints and may help to prevent or limit damage. Elective surgery is discouraged due to the high possibility of complications. Alternative treatment There are anecdotal reports that large daily doses 0.04-0.14 oz (1-4 g) of vitamin C may help decrease bruising and aid in wound healing. Constitutional homeopathic treatment may be helpful in maintaining optimal health in persons with a diagnosis of EDS. An individual with EDS should discuss these types of therapies with their doctor before beginning them on their own. Therapy that does not require medical consultation involves protecting the skin with sunscreen and avoiding activities that place stress on the joints. Prognosis The outlook for individuals with EDS depends on the type of EDS with which they have been diagnosed. Symptoms vary in severity, even within one sub-type, and the frequency of complications changes on an individual basis. Some individuals have negligible symptoms while others are severely restricted in their daily life. Extreme joint instability and scoliosis may limit a person's mobility. Most individuals will have a normal lifespan. However, those with blood vessel involvement, particularly those with EDS vascular type, have an increased risk of fatal complications.EDS is a lifelong condition. Affected individuals may face social obstacles related to their disease on a daily basis. Some people with EDS have reported living with fears of significant and painful skin ruptures, becoming pregnant (especially those with EDS vascular type), their condition worsening, becoming unemployed due to physical and emotional burdens, and social stigmatization in general.Constant bruises, skin wounds, and trips to the hospital take their toll on both affected children and their parents. Prior to diagnosis parents of children with EDS have found themselves under suspicion of child abuse.Some people with EDS are not diagnosed until well into adulthood and, in the case of EDS vascular type, occasionally not until after death due to complications of the disorder. Not only may the diagnosis itself be devastating to the family, but in many cases other family members find out for the first time they are at risk for being affected.Although individuals with EDS face significant challenges, it is important to remember that each person is unique with their own distinguished qualities and potential. Persons with EDS go on to have families, to have careers, and to be accomplished citizens, surmounting the challenges of their disease. Key terms Arthrochalasia — Excessive loosness of the joints.Blood vessels — General term for arteries, veins, and capillaries that transport blood throughout the body.Cartilage — Supportive connective tissue that cushions bone at the joints or which connects muscle to bone.Collagen — The main supportive protein of cartilage, connective tissue, tendon, skin, and bone.Connective tissue — A group of tissues responsible for support throughout the body; includes cartilage, bone, fat, tissue underlying skin, and tissues that support organs, blood vessels, and nerves throughout the body.Dermatosparaxis — Skin fragility caused by abnormal collagen.Hernia — A rupture in the wall of a body cavity, through which an organ may protrude.Homeopathic — A holistic and natural approach to healthcare.Hyperextensibility — The ability to extend a joint beyond the normal range.Hypermobility — Unusual flexibility of the joints, allowing them to be bent or moved beyond their normal range of motion.Joint dislocation — The displacement of a bone.Kyphoscoliosis — Abnormal front-to-back and side-to-side curvature of the spine.Ligament — A type of connective tissue that connects bones or cartilage and provides support and strength to joints.Osteoarthritis — A degenerative joint disease that causes pain and stiffness.Scoliosis — An abnormal, side-to-side curvature of the spine.Tendon — A strong connective tissue that connects muscle to bone.Uterus — A muscular, hollow organ of the female reproductive tract. The uterus contains and nourishes the embryo and fetus from the time the fertilized egg is implanted until birth.Vascular — Having to do with blood vessels. Resources Periodicals "Clinical and Genetic Features of Ehlers-DanlosSyndrome Type IV, the Vascular Type." The New England Journal of Medicine 342, no. 10 (2000)."Living a Restricted Life with Ehlers-DanlosSyndrome." International Journal of Nursing Studies 37 (2000): 111-118. Organizations Ehlers-Danlos Support Group-UK. PO Box 335, Farnham, Surrey, GU10 1XJ. UK 01252 690 940. http://www.atv.ndirect.co.uk.Elhers-Danlos National Foundation. 6399 Wilshire Blvd., Ste 203, Los Angeles, CA 90048 (323) 651-3038. Fax: (323) 651-1366. http://www.ednf.org. Other GeneClinics. http://www.geneclinics.org. cutis [ku´tis] skin.cutis anseri´na goose flesh.cutis hyperelas´tica Ehlers-Danlos syndrome.cutis lax´a a group of connective tissue disorders in which the skin hangs in loose pendulous folds, believed to be associated with decreased elastic tissue formation as well as an abnormality in elastin formation, and usually occurring as a hereditary disorder and occasionally in an acquired form. Ehl·ers-Dan·los syn·drome (EDS), (ā'lĕrz dahn-los'), a group of connective tissue disorders characterized by hyperelasticity and fragility of the skin, hypermobility of the joints, and fragility of the cutaneous blood vessels and sometimes large arteries due to deficient quality or quantity of collagen; the most common types are inherited as autosomal dominant, caused by mutation in one of the following genes: the collagen V alpha-1 gene (COL5A1) on chromosome 9q or the collagen V alpha-2 gene (COL5A2) on 2q or COL3A1 gene on 2q. Ehl·ers-Dan·los syn·drome (ā'lerz dahn'lōs sin'drōm) An inherited disorder of connective tissue characterized by fragile hyperelastic skin and hypermobility of the joints. At least 14 variant forms have been identified and named. Ehlers-Danlos syndrome A genetic disorder in which the skin is abnormally elastic so that it may be greatly stretched. It is, however, unduly fragile and gapes widely when wounded. Joints are also unusually extensible. The condition is due to a widespread defect of polymerization of the protein collagen-one of the basic constructional materials of the body. (Edvard Ehlers, German dermatologist 1863–1937 and Henri Alexandre Danlos, French dermatologist, 1844–1932). Ehlers, Edvard L., Danish dermatologist, 1863-1937. Ehlers-Danlos syndrome - a group of inherited generalized connective tissue diseases. Synonym(s): Meekeren-Ehlers-Danlos syndrome Danlos, Henri-Alexander, French dermatologist, 1844-1912. Danlos phenomenonDanlos syndromeEhlers-Danlos syndrome - see under Ehlers Meekeren, Job van, Dutch surgeon, 1611-1666. Meekeren-Ehlers-Danlos syndrome - Synonym(s): Ehlers-Danlos syndrome Ehl·ers-Dan·los syn·drome (ā'lerz dahn'lōs sin'drōm) Connective tissue disorders characterized by hyperelasticity and fragility of skin, hypermobility of joints, and fragility of cutaneous blood vessels.
随便看	driblets d-riboketose d-ribose dribs dribs and drabs dribu d-ribulose d-ribulose-5-phosphate 3-epimerase dric drice dricort drid dridus' web cataloging project drie driech dried dried alum dried aluminum hydroxide gel dried and salted cod dried apricot dried blood cell analysis dried blood spot dried currant dried distillers grain dried distiller's grains and solubles