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What is
Ehlers-Danlos Syndrome?
Individuals with EDS have a defect in their connective tissue, the tissue which
provides support to many body parts such as the skin, muscles and ligaments.
The fragile skin and unstable joints found in EDS are the result of faulty collagen.
Collagen is a protein which acts as a "glue" in the body, adding strength
and elasticity to connective tissue.
Ehlers–Danlos syndrome (EDS) is a heterogeneous group of heritable connective
tissue disorders, characterized by articular(joint) hypermobility, skin extensibility
and tissue fragility.There are six major types of EDS. The different types of
EDS are classified according to their manifestations of signs and symptoms.Each
type of EDS is a distinct disorder that "runs true"in a family. This
means that an individual with Vascular Type EDS will not have a child with Classical
Type EDS.
Clinical manifestations of EDS are most often joint and skin related
and may include:
Joints: joint hypermobility; loose/unstable joints
which are prone to frequent dislocations and/or subluxations; joint pain; hyperextensible
joints (they move beyond the joint's normal range); double jointedness; early
onset of osteoarthritis.
Skin: soft velvet–like skin; variable skin hyper-extensibility;
fragile skin that tears or bruises easily (bruising may be severe); severe scarring;
slow and poor wound healing; development of molluscoid pseudo tumors (fleshy
lesions associated with scars over pressure areas), small harmless bumps under
skin
Miscellaneous/Less Common: eye problems; nearsightedness,
occasionally extreme; chronic, early onset, debilitating musculoskeletal pain
(usually associated with the Hypermobility Type); arterial/intestinal/uterine
fragility or rupture (usually associated with the Vascular Type); Scoliosis
at birth and scleral fragility (associated with the Kyphoscoliosis Type); poor
muscle tone (associated with the Arthrochalasia Type); mitral valve prolapse;
and gum disease.
Links to other sites:
Ehlers-Danlos National Foundation
Ehlers-Danlos Syndrome Support Group
Types
There are six major types of EDS. The different types of EDS are classified
according to the signs and symptoms that are manifested. Each type of EDS is
a distinct disorder that "runs true" in a family. An individual with
Vascular Type EDS will not have a child with Classical Type EDS.
Classical
Type EDS. (Formerly EDS Types I & II)
Marked skin hyperextensibility (stretchy) with widened atrophic scars and joint
hypermobility are found in the Classical Type of EDS. The skin manifestations
range in severity from mild to severe expression. The skin is smooth and velvety
with the evidence of tissue fragility and easy bruisability. Examples of tissue
extensibility and fragility include hiatal hernia, anal prolapse in childhood
and cervical insufficiency. Hernias may be a post-operative complication. Scars
are found mostly over pressure points such as the knees, elbows, forehead and
chin. Molluscoid pseudo tumors(calcified hematomas) associated with scars are
frequently found over pressure points such as the elbows, and spheroids (fat
containing cysts) are usually found the on the forearms and shins.
Complications of joint hypermobility include sprains, dislocations/subluxations
and pes planus (flat foot) to name a few. Recurrent joint subluxations are common
in the shoulder, patella and temporomandibular joints.Muscle hypotonia and delayed
gross motor development may also be evident.
Clinical Testing - Abnormal electrophoretic mobility of the proa1(V) or proa2(V)
chains of collagen type V has been detected in several but not all families
with the Classical Type. The Classical Type of EDS is inherited in an autosomal
dominant manner.
Hypermobility (Formally EDS Type III)
Joint hypermobility is the dominant clinical manifestation.Generalized joint
hypermobility that affects large (elbows, knees)and small (fingers and toes)
joints is evident in the Hypermobility Type. Recurring joint subluxations and
dislocations are common occurrences. Certain joints, such as the shoulder, patella,
and temporomandibular joint dislocate frequently. The skin involvement(hyperextensibility
and/or smooth velvety skin) as well as bruising tendencies in the Hypermobility
Type are present but variable in severity.
Chronic joint and limb pain is a common complaint amongst individuals with the
Hypermobility Type. Skeletal X-rays are normal. Musculoskeletal pain is early
onset, chronic and may be debilitating. The anatomical distribution is wide
and tender points can sometimes be elicited.
To date, no distinctive biochemical collagen finding has been identified by
researchers. The Hypermobility Type of EDS is inherited in an autosomal dominant
manner.
Vascular (Formally EDS Type IV)
This type is generally regarded as the most serious form of EDS due to the possibility
of arterial or organ rupture. The skin is usually thin and translucent with
veins being seen through the skin. This is most apparent over the chest and
abdomen. There are certain facial characteristics present in some affected individuals.These
manifestations include large eyes, thin nose, lobeless ears,short stature and
thin scalp hair. Also evident is a decrease in subcutaneous tissue, particularly
in the face and extremities.Minor trauma can lead to extensive bruising.
Arterial/intestinal/uterine fragility or rupture commonly arise in this type
of EDS. Spontaneous arterial rupture has a peak incidence in the third or fourth
decade of life, but may occur earlier.Midsize arteries are commonly involved.
Arterial rupture is the most common cause of sudden death. Acute diffuse or
localized abdominal or flank pain is a common presentation of arterial or intestinal
rupture. Life expectancy is shortened with a majority of individuals living
only into their forties. Pregnancies maybe complicated by intra-partum uterine
rupture and pre- and postpartum arterial bleeding.
Joint hypermobility is usually limited to the digits. Tendon and muscle rupture
can occur. Talipes equinovarus (clubfoot) is frequently seen at birth. Other
manifestations that may be found in the Vascular Type include: acrogeria (premature
aging of the skin of the hands and feet); early onset varicose veins; arteriovenousfistula
(an opening between an artery and vein), carotid-cavernousfistula; pneumothorax
(collapse of a lung) /pneumohemothorax (collapse of a lung with a collection
of air or gas and blood); gingivalrecession and complications during and after
surgery (i.e. wounddehiscence).
The Vascular Type of EDS is caused by structural defects in the proa1(III) chain
of collagen type III encodes by COL3A1. This type of EDS is inherited in an
autosomal dominant manner. A skin biopsy can diagnose this type of EDS.
Kyphoscoliosis (Formally EDS Type VI)
Generalized joint laxity and severe muscle hypotonia (weak muscle tone) at
birth are seen in this type of EDS. The muscular hypotonia can be very pronounced
and leads to delayed gross motor development. Individuals with the Kyphoscoliosis
Type present with Scoliosis at birth that is progressive. The phenotype is
most often severe, frequently resulting in the loss of ambulation in the second
or third decade. Scleral fragility may lead to rupture of the ocular globe
after minor trauma.
Tissue fragility including atrophic scars and easy bruising may be seen in
the Kyphoscoliosis Type. Spontaneous arterial rupture can occur. Other findings
may include: marfanoid habitus (Marfan like features); micro cornea (abnormally
small cornea); and radiologically considerable osteopenia (diminished amount
of bone tissue).
Kyphoscoliosis Type EDS is the result of a deficiency of lysylhydroxylase (PLOD),
which is a collagen-modifying enzyme. This type of EDS is inherited in an autosomal
recessive manner. Kyphoscoliosis Type can be diagnosed through a urine test.
Arthrochalasia (Formally EDS Type VII A&B)
Congenital hip dislocation has been present in all biochemically proven individuals
with this type of EDS. Severe generalized joint hypermobility with recurrent
subluxations are seen in individuals with this type of EDS. Other manifestations
of this type may include:skin hyperextensibility with easy bruising; tissue
fragility including atrophic scars; muscle hypotonia; Kyphoscoliosis and radiologically
mild osteopenia.
The Arthrochalasia Type is caused by mutations leading to deficient processing
of the amino-terminal end of proa1(I) [type A] or proa2(I)[type B] chains of
collagen type I. It is inherited in an autosomal dominant manner. A skin biopsy
can also diagnose this type of EDS.
Dermatosparaxis (Formally EDS Type VIIC)
Individuals with Dermatosparaxis Type EDS have severe skin fragility and substantial
bruising. Wound healing is not impaired and the scars are not atrophic. The
skin texture is soft and doughy.Sagging, redundant skin is evident. The redundancy
of facial skin results in an appearance resembling cutis laxa. Large hernias(umbilical,
inguinal) may also be seen. The number of patients reported with this type
of EDS is small.
Dermatosparaxis Type EDS is caused by a deficiency of procollagenI N-terminal
peptidase. It is inherited in a autosomal recessive manner. A skin biopsy can
diagnose this type of EDS.
Other
The current EDS type V (X-linked) has been described in a single family. It
is a rare variant and the molecular basis of which remains unknown.
The current EDS type VIII is similar to the Classical Type except that in addition
it presents with periodontal friability.This is a rare type of EDS. The existence
of this syndrome as an autonomous entity is uncertain.
The EDS type IX was previously redefined as "Occipital Horn syndrome",
an X-linked recessive condition allelic to Menkes syndrome. This was previously
removed from the EDS classification.
The current EDS type X has been described in only one family.
The EDS type XI termed "Familial Joint Hypermobility syndrome"was
previously removed from the EDS classification. Its relationship to the EDS
is not yet defined.