Discovery of a connective tissue dysplasia in the Martin-Bell syndrome.

The fact that a connective tissue dysplasia is a component of the Martin-Bell syndrome was a fortuitous discovery. A 26-month-old developmentally delayed boy had many signs of a connective tissue dysplasia for which he was referred to a University center where he was found to be fragile (X)-positive without confirmation of a connective tissue problem. Sensitized by these events and observations, we were able to predict at a glance in an unrelated family the fragile (X)-positive status of 2 subsequently referred brothers with mental retardation and prominent manifestations of connective tissue dysplasia. Thus, the Martin-Bell syndrome is an incompletely recessive, pleiotropic trait involving CNS, testes and connective tissues. The characteristic facial appearance of affected males largely represents interaction of mental retardation, congenital CNS based muscle hypotonia and connective tissue dysplasia. At the 1983 NIH workshop on XLMR there was a general consensus that a connective tissue dysplasia is a component of the Martin-Bell syndrome, a fact since confirmed by others on the basis of objective measurements of finger joint hypermobility and frequent presence of mitral valve prolapse.