A further whole arm 1;19 translocation with alpha-satellite DNA breakage.

A balanced whole arm translocation (1;19)(p10;q10) was found in a woman with normal phenotype ascertained through a fragile X survey. Chromosome painting with the specific libraries confirmed the cytogenetic diagnosis. Fluorescence in situ hybridization with a chromosome-1 alpha-satellite probe revealed that the breakpoint in chromosome 1 split the alpha-satellite sequences into two blocks. The review of constitutional whole arm translocations revealed a greater participation of some chromosomes with recurrence of translocations t(1;19)(1p19q;1q19p), t(18;20)(18p20q;18q20p) and t(X;17)(Xp17q;Xq17p). The alpha-satellite breakage documented in some derivatives of the recurrent translocations may be related to highly homologous subsets in the involved chromosome pairs, which belong to alpha-satellite subfamilies 1, 2 and 3 respectively. Probably this leads to abnormal chromosome pairing and thus to whole arm translocations.