Klinefelter syndrome and associated fragile-X syndrome.

During screening of male individuals for Fragile-X syndrome in a residential facility for persons with mental retardation, the authors found a 21-year-old profoundly retarded man who displayed facial features and behaviour suggestive of Fragile-X syndrome. The chromosome analysis revealed 47,fra(X)(q27)fra(X)(q27)Y. His physically and intellectually normal sister had 14% of X chromosomes with a fragile site. Her two sons, who were subsequently examined, were found to have Fragile-X syndrome. Thus, the identification of Fragile-X syndrome in the proband during the screening process of a large institution led to the investigation of the proband's family and the subsequent diagnosis of Fragile-X syndrome in the proband's two nephews. The ascertainment of the two affected boys permitted prompt introduction of early intervention and special education services. Genetic counselling of other at-risk family members was carried out.