Aortic hypoplasia and cardiac valvular abnormalities in a boy with fragile X syndrome.

An 18-year-old mentally retarded male with the Martin-Bell syndrome was fragile X positive. He died suddenly with viral pneumonia and myocarditis. At autopsy, generalized tubular hypoplasia of the aorta and a mild coarctation were discovered. The base of the mitral and tricuspid valves showed striking aberrations in elastin distribution and structure by light microscopy. Local collagen alterations were also noted. Comparable changes were seen in the skin elastin as well as a severe depletion of acid mucopolysaccharides. These changes suggest a structural disruption underlying the clinical connective tissue problems in some patients with the fragile X syndrome.