We studied after death a 3-month-old girl whose karyotype was 
45,XX,-15,-17,+der(17),t(15;17)(q13;p13.3) and thus combines abnormalities of 
chromosome 15 associated with the Prader-Willi syndrome and of chromosome 17 
associated with the Miller-Dieker syndrome. This infant had several 
manifestations of the Prader-Willi syndrome in infancy but none of the 
Miller-Dieker syndrome. We propose that essentially no loss of 17p material has 
occurred and confirm previous reports that the critical region for the 
production of the Miller-Dieker phenotype is located subterminally in the 
17p13.3 region.