Cytogenetic studies in mentally retarded Jamaican children - abstract

ABSTRACT

A cytogenetic study of the children attending the school and home of the Jamaican association for Mentally Handicapped Children was undertaken in order to ascertain paritcular sex chromosome abnormalities in males. Eighty-five unselected children were studied. To this group were added 18 children had referred from Paediatric Clinics over the age of 3 because of mental retardation. These were selected, as not all retarded are referred. The children had a physical examination, buccal smears and chromosome studies. The age range was 30-40 years. An attempt at assessment of mental development was made, to divide them into mildly retarded, moderately retarded and severely retarded. There were 75 males and 28 females of which 14 were mildly retarded, 83 moderately retarded and 6 severely retarded. Chromosomal abnormalities were found in 25 children. Of these 18 had trisomy 21, one had 47, XXY and one 47, XYY. Two children with apparently balanced translocations, and 2 with anomalies involving the short arms of the aerocentric chromosomes were found. There was one boy with Fanconi's syndrome of pancytopenia and congenital anomalies. In addition clinical diagnosis of Turner's syndrome in the male, Rubenstein-Taybi syndrome and congenital rubella were made in children without chromosome abnormalities. As might be expected, the mildly retarded group yeild only sex chromosome abnormalities and Fanconi's anaemia, the numbers being too small to draw any conclusions. All the remaining patients with autosomal anomalies occured in the moderately retarded group making up 25 percent of this group, of which 22 percent were mongols. Excluding the mongols from the total number of children, 6 percent of the children had autosomal anomalies, twice the percentage found in surveys of "unselected normal" adults (AU)