Six different alleles that contained from 7 to 12 CAG repeats were detected in the 696 alleles studied (Table 1). The most frequently observed POLG allele was the com mon allele of 10 CAG repeats with a frequency of 87.6% in the infertile/subfertile group and 86.6% in the control group of fertile males. The frequency of the allele of 10 CAG repeats was similar in all five subgroups of infer tile/subfertile patients ranging from 85.1% in the azoosper mia group to 90.2% in the severe oligozoospermia group. The second most frequent allele contained 11 CAG repeats, ranging from 8.0% in severe oligozoospermia group to 11.5% in the azoospermia group. The other four POLG CAG alleles were extremely rare.

The frequency of the different POLG CAG genotypes is given in Table 2. The most frequent genotype was the 10/10, 76.9% in the patient group, 74.8% in the control group. This genotype was designated as a homozygous wild type [3]. Five heterozygous genotypes (7/10, 8/10, 9/10, 11/10, 12/10) and two homozygous mutant geno types (9/11 and 11/11) were also found. The distribution of the 10/10, 10/not10 and not10/not10 genotypes is shown in Figure 2. Homozygous mutant genotypes were found in the control group (two 11/11), azoospermia group (two: one 9/11 and one 11/11), normozoospermia group (one 11/11) and the known cause group (one 11/11) (Table 2 and Figure 2). No homozygous mutant genotypes were found in the severe and mild oligozoospermia groups. The relatively higher frequency of the homozygous mutant genotypes in these three groups (2.8, 2.6 and 3.5%) in comparison with the control group (1.6%) was not statis tically different.

Table 1. Allele frequency of the POLG CAG repeats in different groups of infertile/subfertile males and fertile controls

Table 2. Genotype frequency of the POLG CAG repeats in different groups of infertile/subfertile males and fertile controls