Genetic Determinants for Vivax Malaria Susceptibility in Chiplun (Ratnagiri), Maharashtra, India: A Case-Control Study.

OBJECTIVE

Malaria remains a significant public health challenge in India, with genetic factors potentially influencing both susceptibility and disease severity. This study aimed to investigate the relationship between blood group polymorphisms, α-globin gene deletions, Complement Receptor 1 (CR1) variants, and Gerbich phenotypes with malaria susceptibility in the Chiplun region of Maharashtra, India.

METHODS

In this case-control study, we enrolled 228 microscopically confirmed malaria cases and 2149 healthy individuals as controls from the Chiplun taluka from Ratnagiri district. ABO and Rh blood group typing was performed using standard tube agglutination techniques. α-globin gene deletions were analysed using multiplex PCR. CR1 polymorphisms (intron 27 and exon 22) and Gerbich blood group variations were determined using PCR-RFLP and multiplex PCR approaches respectively. Statistical analyses included chi-square tests, Fisher's exact tests, regression analysis and odds ratios with 95% confidence intervals.

RESULTS

Blood group B+ was associated with increased malaria risk (OR = 1.36, 95% CI: 1.02-1.80, p < 0.05), whilst A+ appeared protective (OR = 0.72, 95% CI: 0.52-0.99, p < 0.05). Most notably, individuals with homozygous-α3·7 deletion genotype showed significantly higher malaria susceptibility (OR = 3.33, 95% CI: 2.00-5.53, p < 0.001). No significant associations were observed between Rh phenotypes, CR1 polymorphisms, or Gerbich variants and malaria susceptibility.

CONCLUSIONS

Our findings demonstrate significant associations between certain blood group phenotypes and α-globin genotypes with malaria susceptibility in the population from Chiplun. The strong association of homozygous-α3·7 deletion with increased malaria risk contradicts the protective effect reported in some populations, highlighting the complex and potentially region-specific nature of genetic factors influencing malaria susceptibility. These results contribute to understanding the genetic epidemiology of malaria in India and may inform targeted public health interventions in similar endemic regions.