Hybridization of chromosome 18 alpha-satellite DNA probe to chromosome 22

Fluorescence in situ hybridization (FISH) of uncultured chorionic villus diploid cells with a chromosome 18 alpha-satellite DNA probe (D18Z1) revealed a third small signal in addition to two large signals. FISH analysis of diploid metaphase cells from cultured chorionic villus cells and from maternal lymphocytes revealed that the third signal resulted from hybridization to the centromere of chromosome 22. This is the first report of a variant involving D18Z1 detected by FISH and of hybridization of alpha-satellite from a sub-metacentric chromosome to the centromere of an acrocentric chromosome. We propose that this inherited variant resulted from insertion of chromosome 18 specific alpha-satellite DNA sequences into the centromeric region of chromosome 22.