Duplication of 16p from insertion of 16p into 16q with subsequent duplication due to crossing over within the inserted segment.

Two members of a large family had a similar multiple congenital anomalies mental retardation (MCA/MR) syndrome and an identical aberration of chromosome 16. Their mothers, who are first cousins, had a different abnormality of one chromosome 16, which appeared to be an acrocentric. We interpret these findings as an insertion of a segment of 16p into 16q. following a three-break rearrangement and meiotic crossing over. The two abnormal children have a duplication of 16p11 leads to p13. The clinical manifestations of these patients differ from those of previously reported cases of dup(16p).