Cytogenetic studies of cryptorchid testes

While cryptorchidism is not usually found in individuals with typical Klinefelter syndrome (47,XXY) it is common in variants such as 49,XXXXY and mosaics. Unilateral or bilateral cryptorchidism occurs in children with 45,X/46,XY mosaicism and in individuals with more complex sex chromosome mosaicism. The common finding among individuals with sex chromosome abnormalities associated with cryptorchidism is the dysgenetic character of the gonad. The occurrence of a normal karyotype in peripheral blood concurrent with tissue mosaicism is well known. We recently studied a 14 yr old female with the Turner phenotype. Her peripheral blood karyotype was 46,XY (75 cells were examined). Chromosome analysis of fibroblast like cells from her dysgenetic gonads revealed 45,X/46,XY/47,XYY mosaicism. Since undescended testes in otherwise phenotypically normal individuals also have dysgenetic features, a study was undertaken to determine if any of these testes exhibited gonadal karyotype mosaicism. Bilateral or unilateral testicular biopsies were obtained from 38 children during orchidopexy. Nine tissue cultures were unsuccessful, while 29 were karyotyped. One of the unsuccessful cultures was from a male patient with the Turner phenotype and normal peripheral blood chromosomes. A patient with the Prader Willi syndrome had normal gonadal chromosomes. A 3rd patient was found to have a 46,XY,Dq+ karyotype in his testes which was later found in peripheral blood leukocytes as well. He had mild mental retardation, nystagmus, and marked facial asymmetry in addition to the cryptorchidism. All of the remaining 26 specimens had normal male karyotypes, 46,XY. Cryptorchidism is not uncommon in patients with autosomal trisomy such as Down syndrome or trisomy D. Only one of 29 subjects whose gonadal tissue was karyotyped had a karyotype abnormality and that was not a mosaic abnormality but was present in all cells examined. These findings are in contrast to the previous report in which 9 of 13 patients with cryptorchidism were reported to have abnormal testicular chromosomes with normal peripheral blood chromosomes. Based on our mostly unremarkable findings, we have concluded that localized tissue mosaicism is an uncommon cause of cryptorchidism in otherwise normal children.