Paternal isodisomy 13 in a normal newborn infant after trisomy rescue evidenced by prenatal diagnosis

Maternal and paternal uniparental disomy of:chromosome 13 have been associa ted with normal phenotypes, We report on a new case of paternal isodisomy 1 3 in a phenotypically normal girl. Prenatal diagnosis had shown a 46,XX,-13 ,der(13;13) karyotype in chorionic villi and a 45,XX,der(13;13) karyotype i n amniocytes and fetal blood. Molecular studies demonstrated that the de no vo der(13;13) was an isochromosome 13 of paternal origin. This observation supports the lack of imprinting effects on chromosome 13 and trisomy rescue as a mechanism leading to uniparental disomy in cases involving isochromos omes. (C) 2000 Wiley-Liss, Inc.