The clinical phenotype in institutionalised adult males with X-linked mental retardation (XLMR)

In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 22 males (i.e. 5 % of the male population) had XLMR, accounting for 36.1 % of the residents diagnosed with a monogenic di sorder (n = 61). Fragile X syndrome (FRAXA) was diagnosed in 16 residents, X-linked mental retardation with marfanoid habitus (Lujan-Fryns syndrome) i n 2, and non-specific X-linked mental retardation (MRX) in 4 males. The 4 M RX-patients included 3 male sibs of a family, carrying a mutation in the IL -1 receptor accessory protein-like gene, and one male patient member of the MRX-44 family (linkage with LOD-score of 2.90). In the group of 215 males with idiopathic mental retardation (MR), family histories and pedigree data were compatible with XLMR in 35 males (35/215 = 16.3 %) from 32 families. Of these 35 males, 5.7 % were microcephalic with dysmorphic features and 5. 7 % macrocephalic; micro-orchidism and macro-orchidism were each found in 1 1.4 %. One macrocephalic male had also macro-orchidism and dysmorphic featu res. In this study, the diagnosis of XLMR could thus be proposed in 57 male s i.e. 13.1 % of the total male population. The clinical phenotype, behavio ural problems and follow-up data in these different subgroups of XLMR are p resented. (C) 2001 Editions scientifiques et medicales Elsevier SAS.