Isodicentric chromosome 18 in an abnormal infant using chromosome specific DNA probe.

A report is made on a rare isodicentric chromosome 18 in an abnormal male infant whose karyotype was 46,XY,idic(18)(p11.31----qter), confirmed by in situ hybridization using non-radioactive biotin-labelled 18 probe. His clinical features were similar to 18 trisomy syndrome. The literature concerning isochromosome 18 is reviewed.