Decisive evidence corroborates a null relationship between MTHFR C677T and chronic kidney disease: A case-control study and a meta-analysis

Can Pharmacogenetic Variants in TPMT, MTHFR and SLCO1B1 Genes Be Used as Potential Markers of Outcome Prediction in Systemic Sclerosis Patients?

Systemic sclerosis (SSc) is a rare connective tissue disorder with highest morbidity and mortality among rheumatologic diseases. Disease progression is highly heterogeneous between patients, implying a strong need for individualization of therapy. Four pharmacogenetic variants, namely TPMT rs1800460, TPMT rs1142345, MTHFR rs1801133 and SLCO1B1 rs4149056 were tested for association with severe disease outcomes in 102 patients with SSc from Serbia treated either with immunosuppressants azathioprine (AZA) and methotrexate (MTX) or with other types of medications. Genotyping was performed using PCR-RFLP and direct Sanger sequencing. R software was used for statistical analysis and development of polygenic risk score (PRS) model. Association was found between MTHFR rs1801133 and higher risk for elevated systolic pressure in all patients except those prescribed with MTX, and higher risk for kidney insufficiency in patients prescribed with other types of drugs. In patients treated with MTX, variant SLCO1B1 rs4149056 was protective against kidney insufficiency. For patients receiving MTX a trend was shown for having a higher PRS rank and elevated systolic pressure. Our results open a door wide for more extensive research on pharmacogenomics markers in patients with SSc. Altogether, pharmacogenomics markers could predict the outcome of patients with SSc and help in prevention of adverse drug reactions.

Associations of MTHFR gene polymorphism with lipid metabolism and risk of cerebral infarction in the Northwest Han Chinese population

Objective

Genetic variation in the methylenetetrahydrofolate reductase (MTHFR) gene may contribute to the development of cerebral infarction (CI); however, results have been inconsistent across studies with different populations, including studies of the Chinese population. The aim of this study was to analyze the effect of MTHFR gene polymorphism on serum lipid and homocysteine levels among patients with CI in the Northwest Chinese Han population.

Patients and methods

A total of 521 CI patients and 524 non-CI controls were enrolled in the study. Polymerase chain reaction and hybridization were utilized to identify MTHFR gene polymorphisms. Multivariate logistic regression analysis was used to assess the associations of MTHFR gene polymorphism with risk of CI.

Results

Frequencies of the TT genotype and the T allele were markedly higher among CI patients than among controls. After stratifying our data by sex and age, we determined that these differences in frequency of the TT genotype and the T allele were statistically significant among participants of two different age brackets and among men, but not among women (i.e., there were no statistically significant differences between female patients and female controls). CI patients and control participants with the CT or TT genotype had significantly higher homocysteine (Hcy) levels than those with the CC genotype. Among CI patients, CT/TT carriers showed significantly lower high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (ApoA-I) levels as compared with CC carriers, but there was no significant difference for control participants. Multivariable logistic regression analysis showed that drinking; smoking; diabetes mellitus; levels of Hcy, direct bilirubin (DB), indirect bilirubin (IB), ApoA-I, and total protein (TP); and TT genotype were significant independent risk factors for CI.

Conclusions

The results suggested that the TT genotype of the MTHFR C677T gene polymorphism, which is associated with hyperhomocysteinemia (HHcy), might be of great clinical significance in the identification of new biomarkers for CI and in the development of individualized preventive and therapeutic strategies.

Vitamin B12 and chronic kidney disease

Chronic Kidney Disease (CKD) is an emerging public health issue with a fast-growing global prevalence. Impairment in vitamin B12 metabolism is considered a nontraditional risk factor of poor outcomes associated with CKD, and there is greater interest from the scientific community than ever before to explore the role and influence of vitamin B12 in CKD. Homocysteine metabolism forms an important component of the vitamin B12 metabolic pathway. Hyperhomocysteinemia is frequently observed in CKD and End-Stage Kidney Disease (ESKD), but its representation as a prognostic marker for CKD outcomes is still not fully clear. This chapter reviews the vitamin B12 and homocysteine metabolic pathways and their dysfunction in CKD states. Biochemical factors and the MTHFR genetic polymorphisms which disrupt vitamin B12 and homocysteine metabolism are explored. The mechanisms of homocysteine-mediated and vitamin B12-mediated tissue damage in CKD are discussed. This chapter reviews current perspective on definition and measurement of plasma vitamin B12 levels in the CKD population. Updated evidence investigating the prognostic role of vitamin B12 for CKD outcomes is presented. Findings from major clinical trials conducted relating to outcomes from multivitamin (including folic acid and vitamin B12) supplementation in nondialysis and dialysis-dependent CKD are highlighted. The prognostic value of vitamin B12 and effects of vitamin B12 supplementation in the context of kidney transplantation and acute kidney injury is also reviewed. Future research considerations are summarized based on evidence gaps in our knowledge base of this topic. Greater abundance of high-level evidence to guide an approach toward vitamin B12 measurement, monitoring and supplementation in CKD may contribute to improved clinical outcomes.