Background: Serine hydroxymethyl transferase (SHMT1) is an enzyme with a particular role in the interconversion of serine and glycine. SHMT1 may contribute to Parkinson's disease pathogenesis and progression through its role in neuronal function.
Objectives: This study aims to assess the role of SHMT1 polymorphism (rs1979277) A/G in predicting the risk and severity of Parkinson's disease in addition to its correlation with vitamin B12 and folic acid serum levels.
Patients and methods: A descriptive case-control study involved 192 participants divided into two groups: (group A) included 96 patients diagnosed as Parkinson's disease and (group B) 96 healthy, age- and sex-matched subjects as controls. SHMT1-SNP genotyping A/G (rs1979277) detection was done. Moreover, the serum levels of folic acid and vitamin B12 were estimated for all patients genotypes.
Results: The GA+AA versus GG genotype were significantly susceptible to Parkinson's disease: OR 95% CI= 2.14 (1.16-3.96) and p-value =0.014. The G allele was protective, and the A allele was a predisposing genetic factor for Parkinson's disease (p-value <0.011 and OR, 95% CI=2.04 (1.36-3.07). Patients with the GA+AA genotype had a statistically significant lower median MMSE total score than those with the GG genotype (16.0 vs. 21.5 years, respectively; p-value = 0.021). However, there was no statistically significant difference between GA+AA vs GG and mean vit-B12 and folate.
Conclusion: Parkinson's disease along with the severity of depression was substantially more likely to develop in people with the genotype GA+AA than GG. Consequently, for Parkinson's disease, the G allele may be protective while the A allele was a genetic risk factor.