Congenital contractural arachnodactyly

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Congenital contractural arachnodactyly is a disorder that affects many parts of the body. People with this condition typically are tall with long limbs (dolichostenomelia) and long, slender fingers and toes (arachnodactyly). They often have permanently bent joints (contractures) that can restrict movement in their hips, knees, ankles, or elbows. Additional features of congenital contractural arachnodactyly include underdeveloped muscles, a rounded upper back that also curves to the side (kyphoscoliosis), permanently bent fingers and toes (camptodactyly), ears that look "crumpled," and a protruding chest (pectus carinatum). Rarely, people with congenital contractural arachnodactyly have heart defects such as an enlargement of the blood vessel that distributes blood from the heart to the rest of the body (aortic root dilatation) or a leak in one of the valves that control blood flow through the heart (mitral valve prolapse). The life expectancy of individuals with congenital contractural arachnodactyly varies depending on the severity of symptoms but is typically not shortened.

A rare, severe form of congenital contractural arachnodactyly involves both heart and digestive system abnormalities in addition to the skeletal features described above; individuals with this severe form of the condition usually do not live past infancy.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the FBN2 gene cause congenital contractural arachnodactyly. The FBN2 gene provides instructions for producing the fibrillin-2 protein. Fibrillin-2 binds to other proteins and molecules to form threadlike filaments called microfibrils. Microfibrils become part of the fibers that provide strength and flexibility to connective tissue that supports the body's joints and organs. Additionally, microfibrils regulate the activity of molecules called growth factors. Growth factors enable the growth and repair of tissues throughout the body.

Mutations in the FBN2 gene can decrease fibrillin-2 production or result in the production of a protein with impaired function. As a result, microfibril formation is reduced, which probably weakens the structure of connective tissue and disrupts regulation of growth factor activity. The resulting abnormalities of connective tissue underlie the signs and symptoms of congenital contractural arachnodactyly.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

The prevalence of congenital contractural arachnodactyly is estimated to be less than 1 in 10,000 worldwide.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormality of the musculature · Very frequent (99-80%)

Abnormality originating in one or more muscles, i.e., of the set of muscles of body.

Abnormally folded helix · Very frequent (99-80%)

Any structural anomaly of the border of the helix, which usually forms a rolled rim but is highly variable in shape.

Arachnodactyly · Very frequent (99-80%)

Abnormally long and slender fingers (spider fingers).

Arthrogryposis multiplex congenita · Very frequent (99-80%)

Multiple congenital contractures in different body areas.

Camptodactyly of finger · Very frequent (99-80%)

The distal interphalangeal joint and/or the proximal interphalangeal joint of the fingers cannot be extended to 180 degrees by either active or passive extension.

Congenital contracture · Very frequent (99-80%)

One or more flexion contractures (a bent joint that cannot be straightened actively or passively) that are present at birth.

Crumpled ear · Very frequent (99-80%)

Distortion of the course of the normal folds of the ear and the appearance of supernumerary crura and folds.

Flexion contracture · Very frequent (99-80%)

A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.

High palate · Very frequent (99-80%)

Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective).

Joint stiffness · Very frequent (99-80%)

Joint stiffness is a perceived sensation of tightness in a joint or joints when attempting to move them after a period of inactivity. Joint stiffness typically subsides over time.

Scoliosis · Very frequent (99-80%)

The presence of an abnormal lateral curvature of the spine.

Slender build · Very frequent (99-80%)

Asthenic habitus refers to a slender build with long limbs, an angular profile, and prominent muscles or bones.

Congenital kyphoscoliosis · Very frequent (99-80%)

Disproportionate tall stature · Frequent (79-30%)

A tall and slim body build with increased arm span to height ratio (>1.05) and a reduced upper-to-lower segment ratio (<0.85), i.e., unusually long arms and legs. The extremities as well as the hands and feet are unusually slim.

Other findings in the same source

From: Orphanet

Additional reported features include Abnormal cardiovascular system morphology (Occasional (29-5%)); Aortic aneurysm (Occasional (29-5%)); Duodenal atresia (Occasional (29-5%)); Ectopia lentis (Occasional (29-5%)); Intestinal malrotation (Occasional (29-5%)); Mitral valve prolapse (Occasional (29-5%)); Tracheoesophageal fistula (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Congenital contractural arachnodactyly is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Congenital contractural arachnodactyly. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.