[Mental deficiency associated with a fragility of the X chromosome].

Fragile X chromosome was studied in 44 male and 9 female children, affected of mental retardation. In 10 males fragile X was positive. All this patients presented mild mental deficiency with and IQ from 55 to 75. Behaviour was generally hyperkinetic except one autistic boy. Most frequent dysmorphic signs were increased head circumference and prominent large ears. Family history for mental retardation was positive almost in all cases. High percentage of children with fragile X syndrome (22.7%) encountered among male patients suggest convenience of screening, for these anomaly, of all boys affected of mild mental deficiency and all those with an autistic behaviour although lacking of dysmorphic characteristics. This will allow to know more on etiology and to offer genetic counseling to families. Although study in girls was negative, authors believe it is interesting to screen fragile X because some females with border line retardation present this chromosomic anomaly.