Double balanced de novo translocations involving chromosomes 4/15 and 5/12 in a mentally retarded boy

This report describes a compound structural rearrangement containing two apparently unrelated reciprocal translocations, one between chromosomes 4 and 15, the other between 5 and 12. It is suggested that the patient's mental retardation and osteosclerosis may be the result of the loss of a small amount of chromosomal material and/or position effect accompanying these translocations.