Ehlers Danlos syndrome is a group of heritable disorders of the connective tissue characterized by hyperextensible skin, joint hypermobility, and abnormalities of the internal organs. Most of these abnormalities result from defects in the structure or function of the collagen protein. Various forms of EDS are known. The spondylodysplastic type is a relatively rare subtype of EDS, which is principally characterized by a progeroid facies, multiple nevi, mild mental retardation, skin hyperextensibility, bruisability, moderate skin fragility, and joint hypermobility noticed principally in the digits.
Mutations in the B4GALT7 (Xylosylprotein 4-Beta-Galactosyltransferase, Polypeptide 7) gene have been shown to be responsible for the progeroid form of EDS. This gene codes for a membrane bound glycoprotein, galactosyltransferase-I, which plays a major role in the formation of proteoglycans. Since proteoglycans form an essential part of the extracellular matrix, and play major roles in several developmental and metabolic processes, it is easy to see how defects in its synthesis could lead to defects in the musculoskeletal system.
Faiyaz-Ul-Haque (2004) described two patients in an extended Arab family with the Progeroid form of EDS. The proband was a 2-year old girl, born to normal consanguineous parents. At birth, she was noted to have unusual facial features. Her developmental milestones were delayed. Upon examination, her height, weight, and head circumference, all were below the 3rd centile. Facial features included a tiny face with frontal bossing, loose facial skin, sparse scalp hair, prominent eyes with antimongoloid slanting of palpebral fissures, midface hypoplasia, low-set ears, small mouth, and defective enamel. She had long fingers and toes with lax interphalangeal joints. She had an interrupted single transverse palmar crease. Deep tendon reflexes were sluggish. X-ray showed bilateral proximal radioulnar synostosis and bowing of the shafts of the radius and ulna, short clavicles with broad medial ends, anterior splaying of ribs, abnormal appearance of distal metaphyses of the humeri and ulna, cone shaped appearance of distal phalanx of first toe, and diffuse osteopenia. Her paternal uncle, also born to consanguineous parents, was 33-years old at the time of examination. His developmental, clinical, and radiological features were similar to the proband. In addition, he also showed bilateral equinovarus deformities with many atrophic scars on the sides of his feet and back of his legs and hips. Parents of both patients were normal. Faiyaz-Ul-Haque (2004) identified a novel homozygous mutation in the B4GALT7 gene that caused a Arg270Cys (p.R270C) change in the protein in both patients.