Neuropsychological studies in families with fragile-X negative X-linked mental retardation

Neuropsychological studies were performed in 82 subjects of 12 families with x-linked, fragile X negative, mental retardation (MR). Subjects were examined with Wechsler tests (WPPSI, WISC-R or WAIS, according to their capabilities), Progressive Matrices, Bender or Santucci and memory tests. Physical findings in 5 families were characterised by micro-orchidism (MiO), microcephaly (MiC), short stature (SS) and non-specific facial features (XMR +/- MiO +/- MiC +/- SS). The 11 males with MR had a very low IQ, ranging from 13 to 37 (mean 21.2 +/- 8.8); this did not constitute a profile definition. Among the females of their families, 4 had subnormal or borderline IQ, respectively 74, 66, 38 and 37. A second group (2 families) had MiO but with normal stature and occipito-frontal circumference (XMR +/- MiO). The 7 males with MR had an IQ ranging from 24 to 43 (mean 35.1 +/- 5.8) and showed frequently better results in performance than in verbal subtests. In these 2 families, 5 females had subnormal or borderline IQ, respectively 77, 72, 71, 70 and 20. In the 5 families of the third group, XMR +/- MaO (fraX-), several affected males had macro-orchidism (MaO) and facial changes similar to those of fragile X syndrome. IQ variability, also in the same family (e.g.: the 3 brothers of family 3 had, respectively, an IQ of 26, 28 and 68; and 2 brothers of family 1 had an IQ of 13 and 63) and different profiles. Two females were severely affected (IQ 16 and 24), while another 4 had an IQ, respectively, of 63, 69, 71 and 72.