Trisomy 9 (pter----q1 to q3): the phenotype as an objective aid to karyotypic interpretation.

The phenotypic findings of three patients whose karyotypic interpretations were uncertain were compared to patients with trisomy 9 (pter---q1 to q3). One with an extra, small acrocentric chromosome and another with a trisomy due to an inherited C/G translocation have a phenotype compatible with the trisomy 9 (pter----q1) syndrome. In a third patient reported with 47,XY,?16+, the trisomy 9p probably extends past the q1 region.