Prenatal diagnosis of an extranumerary i(22p) with normal phenotype.

ABSTRACT

A DA-Dapi and AgNOR-negative extranumerary chromosome was identified prenatally in a male fetus and also found in his normal father. Fluorescence in situ hybridization using repetitive DNA probes showed that the minute marker was positive at both ends for beta-satellite sequences, while its centromere was recognized by a 22 alphoid probe. It is concluded that the non-mosaic familial marker represents a 22p isochromosome.