Chromosomal abnormalities in mentally retarded boys other than down’s syndrome in Indonesian special schools

Abstract

Chromosomal abnormalities is a leading cause of mental retardation. The most common genetic cause of mental retardation is trisomy 21, followed by fragile-X syndrome which is inherited i.e passed on from generation to generation. Chromosomal disorders in mentally retarded children have not been studied in Indonesia. This paper reports a survey of chromosomal abnormalities in mentally retarded children attending special schools for mild mental retardation (type C) in Semarang and two towns in Central Java, Indonesia (Cilacap and Purbalingga). A total of460 pupils as subject (from 6 schools) were clinically screened. A cytogenetic study was made on 164 mentally retarded boys without Down’s syndrome fades. Of the 340 subjects in Semarang, 42 (12.3%) had Down s syndrome clinically. In the rural area we identified 5 (8.7%) Down S syndrome out of 57pupils in Purbalingga and 8 (12.6%) out of 63 pupils in Cilacap. Cytogenetic study in Semarang identified four (3./%) fragile-X syndrome and seven (5.46%) other aneuploid constitutions I he positive fragile-X cytogenetic findings were confirmed with DNA study. Cytogenetic study in the samples from rural area only identified one case of chromosomal abnormality.