A Cytogenetic Study of Heavy Mental Retardates. III. A study on 114 karyotypes with banding techniques and incidence of chromosome abnormalities

A cytogenetic study was conducted on 114 cases with heavy mental retardation who were admitted to National Sanatorium Kamo Hospital and Hiroshima Prefectural Handicapped Children's Hospital. Of the 114 cases, 69 cases were males and 45 cases were females. These patients were classified into two groups according to clinical features: Group I of 58 cases with cerebral palsy and Group II of 56 cases with behavior disorders.
Chromosome slides were prepared in accordance with the standard blood culture procedure. Karyotype analyses were made with the application of the conventional Giemsa staining and G-, C-, and Q-banding differential staining.
Of these cases, 14 cases had abnormal karyotypes, showing an incidence of 12,3%. Of the 14 abnormal cases autosomal abnormalities were observed in 12 cases and sexchromosome abnormalities in 2 cases. And normal variations of no.1, 9, and Y chromosome were found in 11 cases.
Out of the 58 cases with cerebral palsy belonging to Group I, 5 cases (8,6%) and out of 56 cases with behavior disorders belonging to Group II, 9 cases (16,1 %) had abnormal karyotypes.
As a result of the chromosome analyses performed on available relatives of abnormal and normal cases with variations, one abnormal case and two of normal variations were found to be transmitted through the parental line.