A clinical and cytogenetic study of institutionalized mental retardates

One hundred and four out of 110 patients in a residential institution for mental retardates were examined clinically and cytogenetically. Both conventional and folate deficient media were employed in order to detect both conventional chromosomal abnormalities and rare fragile sites. Conventional abnormalities were detected in 18 cases (17%). Rare folate sensitive fragile site at 2q13 was detected in one female patient. The same chromosomal aberration was also detected in the patient's mother who had a normal phenotype. Spontaneous expression of the rare fragile site at 2q13 was also observed.