Neuroblastoma is one of the most frequent tumors in infancy. We analyzed 26 neuroblastomas, two ganglioneuromas, and a neuroblastoma metastasis for mutations and homozygous deletions of the p16 (or MTS1 or CDKN2) gene by means of the polymerase chain reaction (PCR) in combination with the single-strand conformation polymorphism (SSCP) technique and by multiplex PCR analysis. We detected mobility shifts in the SSCP gels in seven cases in the 3 half of exon 2 (named exon 2C) of the p16 gene. By PCR amplification of this particular region and SacII restriction enzyme digestion, we confirmed that those cases had a known polymorphism at codon 140 of the p16 gene. Neither mutations nor homozygous deletions were detected. Our results confirm those of Beltinger et al. (Cancer Res 55:2053-2055, 1995), which showed no p16 mutations or homozygous deletions in 18 primary neuroblastomas and nine tumor-derived cell lines. We conclude that the common pattern of p16 inactivation by homozygous deletion or mutation does not seem to be relevant to the development of neuroblastomas.
The DNA content of spermatogonia was studied by cytophotometric quantification in the testes of cryptorchid children and adults, as well as in age-matched control males. In most cases, the average DNA content of spermatogonia was significantly increased in the cryptorchid testes of children with uni- or bilateral cryptorchidism, as well as in the contralateral scrotal testes of children with unilateral cryptorchidism. In the group of adult men the average DNA content of spermatogonia in the testes was even more increased than in children. There were not significant differences between 4 and 14 years of age, between unilateral and bilateral cryptorchidism, or between cryptorchid testes and contralateral normally descended testes. The DNA content of spermatogonia in the surgically descended testes of 3 children who were re-biopsied 3-4 years after orchidopexy was similar before and after orchidopexy. These findings suggest that the spermatogonia of many cryptorchid males bear a congenital lesion.
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