Unusual in vivo rearrangements of the Y chromosome with mitotic instability in vitro.

An unusual structural rearrangement of the Y chromosome resulting in seven different cell lines was found in a male infant with coronal synostosis as the only major clinical symptom. At least three different events must have occurred to explain the patient's karyotype: nondisjunction, chromosome breakage followed by translocation, and tetraploidization followed by somatic recombination. In addition, the structurally abnormal Y chromosome appeared to be unstable in vitro.