A new case of the trisomy 9P syndrome. Report of a patient with unusual chromosome findings (46,XX/47,XX, + i (9p) and a peculiar congenital heart defect.

A girl is described for whom an unusual chromosome constitution was found and who had a peculiar congenital heart defect. The girl showed the main clinical features of the trisomy 9p syndrome, such as psychomotor retardation, microcephaly and brachycephaly, enophthalmos, antimongoloid eye slant, hypertelorism, abnormal ears, a globulous nose, downward slanting mouth, hypoplasia of phalanges and abnormal palmar creases. In addition, the girl had an incomplete harelip, a cleft palate and a peculiar congenital heart defect, a ventricular septal defect with pulmonary valve stenosis and a marked hypoplasia of the pulmonary trunk, including the bifurcation. Chromosome analysis revealed a mosaicism with normal and abnormal mitoses (47 chromosomes). The extra chromosome was a metacentric E16-like chromosome, which on the basis of the G, R, Q and Giemsa-11-banding could be identified as an isochromosome of the short arm of chromosome 9 (46,XX/47,XX, +i (9) (pter leads to cen leads to pter)). The patient consequently had a partial tetrasomy of the short arm of chromosome 9.