Arthrogryposis, Distal, Type 9

Alternative Names

  • DA9
  • Contractural Arachnodactyly, Congenital
  • CCA
  • Beals Syndrome
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Other congenital malformations

OMIM Number

121050

Mode of Inheritance

Autosomal dominant

Gene Map Locus

5q23.3

Description

Congenital contractural arachnodactyly (CCA) is an autosomal dominant disorder involving the connective tissue that closely resembles Marfan's Syndrome. The disease is typified by a marfanoid habitus, flexion contractures of multiple joints, camptodactyly, kyphoscoliosis, muscular hypoplasia, congenital contractures, arachnodactyly, scoliosis, osteopenia, pectus deformities, and facial abnormalities, including micrognathia, and a highly arched palate. CCA has a severe/lethal form, which manifests in infancy characterized by cardiovascular abnormalities, including aortic root dilatation, and an interrupted aortic arch.

Diagnosis is made on the basis of the clinical features. The major differential diagnosis to be considered is Marfan's Syndrome. However, the characteristic 'crumpling' of the pinna, scoliosis, and contractures, as well as absence of ocular complications in CCA are useful in differentiating CCA from Marfan's Syndrome. In addition, molecular genetic tests are available for confirming the diagnosis of CCA. CCA is managed by symptomatic treatment of the clinical features. The joint contractures and camptodactyly usually improve over time. Prognosis is excellent, unless the disorder is complicated with cardiac problems and/or severe deformities of the vertebra.

Congenital contractural arachnodactyly is caused due to mutations in the Fibrillin 2 gene, located on chromosome 5q23-q31. The gene codes for the extracellular matrix microfibril which regulates the early process of elastic fiber assembly. All mutations detected in the Fibrillin 2 gene in patients with CCA have been found in a region between exons 23 and 34, called the 'neonatal region'. Interestingly, this 'neonatal region' is analogous to the 'neonatal region' of the FBN1 gene, responsible for Marfan's Syndrome. The severe/lethal phenotype has been found to be due to a mutation involving skipping of exon 34. It has been postulated that mutations in FBN2 could directly affect the function of microfibrils in laying down a structural scaffold for later bone deposition, resulting in CCA.

Epidemiology in the Arab World

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Other Reports

Oman

Gupta (2002) described the association of congenital contractural arachnodactyly (CCA) and coronal hypospadias in a male baby. The patient was born to non consanguineous parents by emergency LSCS due to fetal distress and oligohydramnios. There was no family history of CCA. He had normal facies, high arched palate, arachnodactyly, joint contractures of knee and elbows, dolichostenomelia, hypoplasia of calf muscles, crumpled ears, camptodactyly with ulnar deviation of hands and coronal hypospadias with hooded prepuce, but normal scrotum and testis. He was found to have a short systolic cardiac murmur, and eye examination was normal. X-ray showed long bones and widening of the knee joints. Ultrasound of the abdomen was normal. The baby was discharged after an uneventful stay at the hospital for three days.

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