Physical and mental defect of chromosomal origin in four individuals of the same family. Trisomy for the short arm of 9.

A family with the reciprocal translocation t(9;22)(q13;q11) segregating in genetically balanced and unbalanced form is identified. The clinical features of four members with trisomy for the short arm of 9, and the proximal part of the long arm of 9, are described in detail. Features in common are summarized and compared with developmental abnormality observed in other examples of trisomy for the short arm of 9. An attempt is made to delineate further the clinical features commonly seen in trisomy for the short arm of 9.