In the husband, peripheral blood homocysteine level was 47.8 umol/L (reference value: 0–15 umol/ L) and folate level was 3.58 ng/mL (reference value: 3.1–19.9 ng/mL); evaluation of semen quality showed asthenospermia and sperm abnormalities; a sperm DNA fragment test showed a high proportion of sperm had significant DNA fragmentation; and analysis of the MTHFR gene revealed the MTHFR C677T homozygous TT genotype. The gene discussed is MTHFR; the disease is Reduced sperm motility.