New Finding of Protrusio Acetabuli in Two Families with Congenital Contractural Arachnodactyly

Abstract

Congenital contractural arachnodactyly is an autosomal dominant disorder of connective tissue and is associated with skeletal features similar to those seen with Marfan syndrome1. Congenital contractural arachnodactyly and Marfan syndrome are linked to mutations in the highly homologous but distinct genes FBN2 (5q23-q31) and FBN1 (15q15-q21), which encode fibrillin 2 and fibrillin 1, respectively2. Fibrillins are major components of extracellular matrix microfibrils, which play an essential role in the formation of elastic fiber and the deposition of tropoelastin and which perform anchoring functions in some tissues3. As a consequence of the abnormal microfibrillogenesis that is seen in association with congenital contractural arachnodactyly and Marfan syndrome, complications may be found in the mesodermal tissues (i.e., the ocular tissue, the skeletal, cardiovascular, pulmonary, and muscular systems, and the skin and integumentum). The phenotypic similarity at times makes it clinically difficult to differentiate congenital contractural arachnodactyly from Marfan syndrome. This is illustrated by the observation that Antoine Marfan's original patient may actually have had congenital contractural arachnodactyly and not what is known today as Marfan syndrome4. Contractures are seen in both syndromes. However, the contractures in patients with congenital contractural arachnodactyly are congenital and tend to improve spontaneously, whereas the contractures in Marfan syndrome are developmental and may be progressive1. Ectopia lentis was reported to occur in 60% of 160 patients with Marfan syndrome5. In contrast, to our knowledge, there has been only one report of ectopia lentis in association with congenital contractural arachnodactyly, in a patient with bilateral ectopia lentis6. The presence of a congenital heart defect strongly suggests the diagnosis of Marfan syndrome, although mitral valve prolapse7, atrial septal defects, and ventricular septal defects are also occasionally found in patients with congenital contractural arachnodactyly8 …