X-linked mental retardation with variable stature, head circumference, and testicular volume linked to Xq12-q21

Clinical and molecular studies are reported on a family with X-linked mental retardation (XLMR) in which there are eight affected males in three generations. Although the males have somatic manifestations, these are variable and in most cases do not allow clear distinction of affected and unaffected males. Affected males are shorter and have a smaller head circumference. Several also have a sloping forehead (5/8), hearing loss (3/8), cupped ears (2/8), and small testes (4/6). An LOD score of 4.41 with zero recombination was obtained at locus DXS1166 in Xq13.2. This family highlights the difficulty in classifying XLMR conditions as either nonsyndromic or syndromic because of the variable somatic manifestations observed in the affected males.