MOSAIC TETRASOMY-8P - MOLECULAR CYTOGENETIC CONFIRMATION AND MEASUREMENT OF GLUTATHIONE-REDUCTASE AND TISSUE-PLASMINOGEN ACTIVATOR LEVELS

We report the case of a 5-year-old girl with severe developmental disa bilities, skeletal anomalies, hypotonia, rectal atresia, malrotation o f the intestine, horseshoe kidney, vesicoureteric reflux, and minor fa cial anomalies. Conventional cytogenetic techniques suggested that she had a mosaic 46,XX/47,XX, + i(8p) constitution, and the identity of t he isochromosome was confirmed by in situ hybridization and chromosome painting. Polymorphic DNA markers are consistent with the i(8p) havin g arisen as the result of a segregation error and centromere misdivisi on at the second maternal meiotic division. The i(8p) was seen in 17/2 5 (68%) lymphocytes at the age of one month but had declined to 31/100 (31%) cells by the age of 5 years. At this time the i(8p) was seen in 30/68 (44%) cultured skin fibroblasts. The proposita had an approxima tely twofold increase in red cell glutathione reductase activity but a normal level of tissue-plasminogen activator. These enzyme results ar e consistent with the known localisation of the glutathione reductase gene on the short arm of chromosome 8 but suggest that the tissue-plas minogen activator gene may map outside this region. (C) 1993 Wiley-Lis s, Inc.