45,X/46,XY mosaic patients exhibit a wide phenotyp- ic spectrum, ranging from normal females and females with Turner syndrome and normal males with mild hypospadias, to male or female pseudohermaphroditism (1). Prenatally diagnosed cases of 45,X/46,XY mosaicism

45,X/46,XY mosaic patients exhibit a wide phenotypic spectrum, ranging from normal females and females with Turner syndrome and normal males with mild hypospadias, to male or female pseudohermaphroditism (1). Prenatally diagnosed cases of 45,X/46,XY mosaicism represent an unbiased group. In over 90% of this group a normal male phenotype has been found. However, the postnatal diagnosis group is most probably biased by ascertainment because usually, phenotypically abnormal individuals are referred for cytogenetic studies (2,3). This case report describes a rare instance of 45,X/46,XY mosaicism in which the 45,X0 karyotype was diagnosed prenatally by amniocentesis. After termination of the pregnancy, chromosomal analysis of the fetal cutaneous biopsy material and fetal cord blood cells revealed the mosaic karyotype 45,X/46,XY at a ratio of 30/70.