The testis-specific poly(A) polymerase beta (PAPOLB) gene was first identified as the intronless gene TPAP in
mice. In TPAP-deficient mice, spermiogenesis is arrested due to altered post-transcriptional gene regulation, including
translational activation via the cytoplasmic polyadenylation of mRNAs. To investigate the possible association between
variations in PAPOLB and impaired spermatogenesis in Japanese males, we screened for genetic variations in PAPOLB
using DNA from 282 sterile male patients and 96 proven-fertile male volunteers using direct sequencing methods on
blood samples. Seven single nucleotide polymorphisms in the coding sequence and one DNA insertion in the 5'
untranslated region of PAPOLB were found. These genetic variations were not present at statistically significant levels;
however, the results of this study may be useful in future large-scale analyses of the association between PAPOLB and