Association of the polymorphism of the CAG repeat in the mitochondrial DNA polymerase gamma gene (POLG) with testicular germ-cell cancer

Abstract

BackgroundA possible association between the polymorphic CAG repeat in the DNA polymerase gamma (POLG) gene and the risk of testicular germ-cell tumours (TGCT) was investigated in this study. The hypothesis was prompted by an earlier preliminary study proposing an association of the absence of the common 10-CAG-long POLG allele with testicular cancer as well as previously reported in some European populations’ association with male subfertility, which is a condition carrying an increased risk of TGCT. Patients and methodsThe number of CAG repeats in both POLG alleles was established in 243 patients with TGCT and in 869 controls by the analysis of the genomic DNA fragment. ResultsA significantly higher proportion of men homozygous allele of other than the common 10 CAG repeats was found among the patients with TGCT in comparison to the controls (4.9% versus 1.3%, respectively, P = 0.001). The vast majority of the homozygous patients had a seminoma (11 of 12; 97%), despite that only about half (55%) of the studied patients had this tumour type. ConclusionsThe findings indicate that the POLG polymorphism may be a contributing factor in the pathogenesis of TGCT particularly in seminoma, but the mechanisms remain to be elucidated.