Open AccessA chromosome survey of 1062 mentally retarded patients. Evaluation of a long‐term study at the Rinnekoti Institution, Finland
Author(s) -
GRIPENBERG ULLA,
HONGELL KARIN,
KNUUTILA SAKARI,
KäHKÖNEN MARKETTA,
LEISTI JAAKKO
Publication year - 1980
Publication title -
hereditas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 50
eISSN - 1601-5223
pISSN - 0018-0661
DOI - 10.1111/j.1601-5223.1980.tb01700.x
Subject(s) - chromosomal translocation , mentally retarded , karyotype , trisomy , chromosome , biology , genetics , pediatrics , medicine , psychology , developmental psychology , gene
During 1962–79 chromosome studies were performed on 1062 patients at the Rinnekoti Institution for the Mentally Retarded. Conventional stainings, occasionally supplemented with autoradiography, were used during the first 10 years; slightly less than half the cases were studied in this way. The rest were stained by the banding techniques. Of the patients studied 305 had Down's syndrome. Regular 21‐trisomy was found in 283 of these cases (92.8 %), mosaicism in 4 cases (1.3 %), translocations in 15 cases (4.9 %) and rare aberrations in 3 cases (1.0 %). GqGq translocations were more frequent than DqGq translocations. The remaining patients (757) had mental retardation, mostly associated with congenital defects. In 713 (94 %) of them the karyotype was normal. Excess of chromosome material was found in 17 patients, and loss of chromosome material in 14; 12 of these cases represented known autosomal syndromes. In addition, 6 balanced translocations were identified, two of them in patients with otherwise unbalanced karyotypes. Various types of sex chromosome aberrations were found in 10 patients (one of whom also had 21‐trisomy). The results confirm the significant contribution of autosomal aberrations to the genesis of severe mental retardation. Sex chromosome aberrations are responsible for some of the cases of severe mental retardation.