[Diagnosis of minor chromosome modifications by molecular cytogenetics].

Chromosomal in situ hybridization with radioactive probes allows the detection of single copy DNA segments of very small size. In two phenotypically normal individuals, classical chromosomal analysis revealed a small partial deletion of chromosome 18 short arm. In situ hybridization of probe D18S3, located at 18p13, showed in both instances a balanced reciprocal translocation: 46,XY,t(5;18) (p153;p112) and 46,XX,t(18;22)(p111;p11), respectively.