Duplication 8p syndrome: Studies in a family with a reciprocal translocation between chromosomes 8 and 12

Abstract

We report a family in which six individuals were carriers of a translocation between chromosomes 8 and 12. The balanced carriers had a chromosome constitution: 46,XX or 46,XY,t(8;12)(021;p13). Six individuals in five generations were mentally retarded. Three of them were examined; their chromosome constitution was 46,XX or 46,XY,der(12),t(8;12)(p21;p13); thus they had a duplication of 8pter→8p21 and possible deficiency of 12pter→12p13. The activities of the enzymes that are coded by genes on 8p (glutathione reductase, GSR, E.C. 1.6.4.2.) and 12p (triosephosphate isomerase, TPI, E.C. 5.3.1.1.; lactate dehydrogenase-B, LDH-B, E.C. 1.1.1.27.; and glyceraldehyde-3-phosphate dehydrogenase, G3PD, E.C. 1.2.1.12.) were normal in these individuals. These findings helped in interpreting the position of the break points in the respective chromosomes. The phenotypic findings in our patients are discussed. Segregation analysis indicates no significant variation from a 25% recurrence risk for each of the possible genotypes in the offspring of balanced carriers.