The karyotype 46,XY, dup(1) (p22.3p32.3) was found in a 10-year-old pa
tient with sex reversal, mental retardation and multiple dysmorphic fe
atures. In other cases with duplication 1p but different breakpoints c
ryptorchidism and genital ambiguity have been observed suggesting the
dosage effect of a locus in 1p involved in sex differentiation.