RESUMEN
<p><b>OBJECTIVE</b>To explore the association between parental genetic polymorphism of methylenetetrahydrofolate reductase (MTHFR) 677C/T and occurrence of nonsyndromic cleft lip with or without cleft palate (NSCL/P) in offspring in Shandong Province.</p><p><b>METHODS</b>MTHFR genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Parents of 89 NSCL/P patients treated at Qilu Hospital from August, 2006 to August, 2008 and those of 64 healthy children were recruited in this case-control study.</p><p><b>RESULTS</b>Frequencies of T and C alleles in mothers of patients and healthy children were 65.73% and 46.09%, and 34.27% and 53.91%, respectively (Chi-square=13.663, P<0.01). Offspring whose mothers had T alleles were 2.243 times more likely to develop NSCL/P (95%CI: 1.408-3.572). Frequencies of T and C alleles in fathers of patients and healthy children were 62.92% and 55.47%, and 37.08% and 44.53%, respectively (Chi-square=2.222, P>0.05). The chance for parents of the patient and control groups to bear an affected fetus carrying homozygous mutations were 43% and 29%, respectively (P>0.05).</p><p><b>CONCLUSION</b>In Shandong Province, maternal genotype for the MTHFR 677C/T polymorphism has a significant impact on the occurrence of NSCL/P in their offspring, whilst paternal genotype for this polymorphism may not be a risk factor for NSCL/P in their offspring.</p>