Detection of TSPY protein in a unilateral microscopic gonadoblastoma of a Turner mosaic patient with a Y-derived marker chromosome

Gonadoblastomas are seen almost exclusively in dysgenetic gonads of patient s with a chromosomal mosaicism of 45,X and an additional Y-bearing cell lin e. This paper presents a case of a Turner mosaic patient with 45,X/46,X,+ma r karyotype, who developed a unilateral microscopic gonadoblastoma, Cytogen etic and molecular analysis confirmed a Y-chromosomal origin of the marker chromosome, with a deletion of the distal Yq arm and the proposed region of a so far undefined gonadoblastoma locus (GBY) present, One of the candidat e genes within the postulated GBY region is TSPY (testis-specific protein Y -encoded), To study the TSPY protein expression, an anti-fusion protein ant ibody was used for immunohistochemistry of the patient's gonads, In contras t to the dysgenetic gonad, an intense immunoreaction was found in gonadobla stoma tumour cells of the other gonad. These results confirm the high level of TSPY protein expression by these cells and demonstrate the value of thi s antibody as an additional marker to confirm the diagnosis of gonadoblasto ma. Copyright (C) 1999 John Whey & Sons, Ltd.