The (TAAAA)n polymorphism of sex hormone-binding globulin gene is not associated with testicular maldescent.

The aim of this family-based study was to investigate the potential association/genetic linkage of the (TAAAA)n polymorphism of sex hormone-binding globulin gene proximal promoter with testicular maldescent (TMD). Genomic DNA was extracted from the peripheral blood of 487 subjects (174 index families): (i) 180 children with all phenotypes of TMD, (ii) 307 parents (156 mothers and 151 fathers). Conventional polymerase chain reaction amplification products were electrophoresed on 10% nondenaturating polyacrylamide gel and visualised by silver staining. After excluding ambiguous parental-child trios and most cases of index families with missing parental genotypes, 429 individuals were left for analysis: 138 completely typed nuclear families (five included a second affected child) and five child-parent couples (one parent missing). Eight fathers presented history of TMD, that is, a total of 156 cases with TMD were analysed. Alleles were analysed with the affected family-based control method and logistic regression-based extension of the transmission disequilibrium test for multiallelic loci. (ΤΑΑΑΑ)n polymorphism analysis revealed six alleles based on repeat numbers (n=5-10). No association/genetic linkage between the (TAAAA)n polymorphism and TMD was detected. Other factors should be investigated to potentially explain the genetic predisposition that seems to exist in at least a subgroup of these patients.