Partial trisomy of distal 8q derived from mother with mosaic 8q23.3----24.13 deletion, and relatively mild expression of trichorhinophalangeal syndrome I.

A 17-month-old girl with a partial trisomy of distal 8q derived from her mother, who has a mosaic 8q23.3----q24.13 deletion, was studied. Both showed a relatively mild phenotype of trichorhinophalangeal syndrome I. The karyotype of the proposita was designated as: 46,XX,-8,+der(8),inv ins(8;8)(p23.1;q24.13q23.3)mat. Her phenotype was considered similar to that of her mother despite the trisomies of distal 8q. She seems to be the first example of a partial trisomy of distal 8q derived from a parent with an interstitial deletion of a distal 8q segment and trichorhinophalangeal syndrome I.