Trisomy for the distal segment of the short arm of chromosome 17 in a boy with mild mental retardation and some dysmorphic features.

The authors describe a boy with a triangular face, wide forehead, telecanthus, large ears, prominent root of the nose, long and bulging philtrum, thin upper lip, everted lower lip, high arched palate, micrognathism, pointed chin, overriding toes, joint laxity, and mild mental retardation. Cytogenetic investigation disclosed the presence of an added chromosome, a very small acrocentric, consisting in the presence of the last band of the short arm of chromosome 17. This anomaly results from a 3:1 mal segregation of a balanced (13q17p) reciprocal maternal translocation leading to a trisomy 17pter. This is a previously undescribed chromosome anomaly.