MOSAIC TRISOMY-22 - A CASE PRESENTATION AND LITERATURE-REVIEW OF TRISOMY-22 PHENOTYPES

In a case of mosaic trisomy 22 the trisomic cells were detected primar ily in fibroblasts. Results of initial lymphocyte chromosome analysis were normal. However, mosaicism was suspected because the patient had hypomelanosis of Ito, hemiatrophy, failure to thrive, and mental retar dation. Mosaicism was confirmed in cultured fibroblasts. Repeat cytoge netic analysis of peripheral blood demonstrated a low level of trisomi c metaphase cells, which was confirmed by interphase fluorescent in si tu hybridization (FISH) analysis. Molecular studies supported maternal disomy in the child's disomic cells. The phenotype of this condition overlaps that of non-mosaic trisomy 22 chromosome mosaicism in general and to some extent the Ullrich-Turner syndrome phenotype. Improved cy togenetic and molecular techniques now allow better delineation of ane uploidy syndromes. Molecular and FISH studies added information about this case (mosaicism and uniparental disomy) not appreciated by routin e cytogenetic analysis of lymphocytes. The detection of low-level mosa icism and/or uniparental disomy in such cases may change the clinical classification and our understanding of pathogenesis and recurrence ri sk of these disorders. (C) 1997 Wiley-Liss, Inc.