Complete maternal isodisomy of chromosome 8 in an individual with an early-onset ileal carcinoid turner

Uniparental disomy (UPD) is a condition in which diploid individuals posses s a chromosome pair from a single parent. In some instances, UPD causes an abnormal phenotype due to imprinting effects, reduction to homozygosity at recessive disease loci, or trisomy mosaicism, Here we report the first acco unt of an individual with apparently nonmosaic complete maternal isodisomy of chromosome 8. This individual was identified during routine genotyping i n a genome-wide search for type 2 diabetes susceptibility genes, although h e does not have diabetes. He is of normal appearance, stature, and intellig ence, but there is an unusual history of early onset ileal carcinoid. The d iscovery of other maternal UPD 8 cases will be necessary to define whether this condition causes a distinct phenotype, Am. J, Med, Genet, 93:207-210, 2000, Published 2000 Wiley-Liss, Inc.dagger