rDNA and acrocentric chromosomes in man. I. rDNA levels in a subject carrier of a 8p/13p balanced translocation and in his unbalanced son.

A malformed female infant was found to have a 46,XX complement with a chromosome 8 shorter than normal with a secondary constriction and satellites on the short arm. Chromosome studies on the clinically normal father showed a balanced translocation between chromosome 8 and 13, i.e., 46,XY,t(8;13) (p21 p12). The proposita, carrier of the unbalanced form of the translocation, resulted partially monosomic for short arm of chromosome 8 (8p-) and partially trisomic for short arm of chromosome 13. The levels of DNA complementary to rRNA (normal in the father who had 10 NOR and increased in the proposita who had 11 NOR) confirmed our interpretation of the rearrangement.