A rare case of ambiguous genitalia.

Genes on the Y chromosome are essential for normal sex determination and sex differentiation of male genitalia. However, genes on the X chromosome and other autosomes have been shown to be anti-testes and have a detrimental effect on this process. Addition of X chromosomes to the 46,XY karyotype results in seminiferous tubules dysgenesis, hypogonadism and malformed genitalia. We report a term male newborn with 49,XXXXY syndrome presenting with ambiguous genitalia, multiple extra-gonadal anomalies, facial dysmorphism, and radioulnar synostosis.