Causal relationship between dietary intake and IgA nephropathy: a Mendelian randomization study

Area of Science:

• Nephrology
• Genetic Epidemiology
• Nutritional Science

Background:

• Dietary factors are linked to immunoglobulin A nephropathy (IgAN).
• The causal relationship between diet and IgAN remains unclear.
• Genome-wide association study (GWAS) data offers insights into genetic predispositions.

Purpose of the Study:

• To determine the causal association between 26 dietary exposures and IgAN.
• To leverage Mendelian randomization (MR) for robust causal inference.
• To identify specific dietary components influencing IgAN risk.

Main Methods:

• Two-sample Mendelian randomization (MR) analysis using publicly available GWAS data.
• Employed inverse variance weighting (IVW), MR-Egger regression, and weighted median methods.
• Assessed horizontal pleiotropy using MR-Egger intercept and MR-PRESSO tests, and instrument heterogeneity with Cochran's Q statistics.

Main Results:

• Alcohol intake frequency showed a causal association as a risk factor for IgAN (OR = 1.267, P = 0.001).
• Cheese intake (OR = 0.626, P = 0.0001), cereal intake (OR = 0.652, P = 0.033), and sushi intake (OR = 0.145, P = 0.049) were identified as protective factors.
• No significant causal relationships were found for other dietary exposures.

Conclusions:

• Genetic evidence suggests alcohol intake frequency increases IgAN risk.
• Consumption of cheese, cereal, and sushi may reduce the risk of developing IgAN.
• Further research is warranted to validate these dietary associations in IgAN.