rs116971963 (CDRT7-CDRT8): Blood Mercury GWAS

Key takeaways

• This variant in the CDRT7-CDRT8 region was identified in a genome-wide association study examining blood mercury levels in European pregnant women and children, but did not reach genome-wide significance.
• No genetic variant in the study reached the conventional threshold for a confident association (p < 5 × 10^-8), placing all findings - including this one - in the preliminary, hypothesis-generating category.
• Genetics may explain roughly 24% of blood mercury variability in pregnant women, though the estimate carries wide uncertainty (95% CI: 16.9%-46.4%).
• Associations between variants and blood mercury were highly discordant between pregnant women and children, suggesting that age or life stage may substantially modify how genes relate to mercury levels.
• The primary source of blood mercury in most populations is dietary methylmercury from predatory fish such as swordfish, tuna, and king mackerel.

What the research says A genome-wide association study (GWAS) - a method that scans hundreds of thousands of genetic variants across the genome for statistical links to a measurable trait - tested variants against log-transformed blood mercury levels in 2,893 European pregnant women from the Avon Longitudinal Study of Parents and Children and 1,042 children from the Human Early Life Exposome study. The study identified 16 variants surpassing a suggestive significance threshold (p < 1 × 10^-5) in pregnant women and 21 in children, but none reached genome-wide significance (p < 5 × 10^-8) in either group, and no variant cleared the suggestive bar in both cohorts. Associations were described as "highly discordant" between the two populations, which the authors attributed to possible age-dependent differences in mercury metabolism, gene-age interactions, or differing dose-response patterns.

Reported associations

• Blood mercury levels (pregnant women): Among 16 variants surpassing a suggestive threshold (p < 1 × 10^-5) in 2,893 European pregnant women; none reached genome-wide significance, and no effect size specific to this variant is reported in the available study text.
• Blood mercury levels (children): Among 21 variants above the suggestive threshold in 1,042 children; results were highly discordant with those in pregnant women, and no variant surpassed the suggestive threshold in both groups.

Evidence quality The evidence supporting any association between this variant and blood mercury levels is weak and preliminary. Neither cohort was large by modern GWAS standards (pregnant women: n = 2,893; children: n = 1,042), and no variant reached genome-wide significance (p < 5 × 10^-8) in either sample. Heritability of blood mercury was estimated at 24.0% (95% CI: 16.9%-46.4%) in pregnant women but could not be reliably determined in children. The strong discordance of associations across the two populations - with no overlap above the suggestive threshold - is unusual and raises the likelihood that some signals are false positives rather than true genetic effects. The study authors explicitly call for external validation. No replication data are available in the provided study text.

Lifestyle considerations

• Predatory fish (nutrition, mixed, low): Long-living predatory fish such as swordfish, tuna, and king mackerel accumulate the highest methylmercury concentrations through bioaccumulation up the food chain and are identified as the primary source of dietary mercury exposure in most populations.