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Updated: May 10, 2026

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Published on: May 23, 2025
Effect modification by transferrin C2 polymorphism on lead exposure, hemoglobin levels, and IQ
Ananya Roy1, Adrienne S Ettinger, Howard Hu
1Department of Chronic Disease Epidemiology, Yale School of Public Health, New Haven, CT, United States.
The transferrin C2 variant may increase children's susceptibility to lead's neurotoxic effects, diminishing hemoglobin's protective role. This highlights genetic factors in lead poisoning outcomes.
Area of Science:
- Environmental Health
- Neuroscience
- Genetics
Background:
- Iron deficiency and lead exposure are global health concerns linked to neurocognitive deficits.
- Genetic variations in iron transport pathways can influence lead absorption and toxicity.
Purpose of the Study:
- To investigate if the transferrin (TF) C2 polymorphism modifies the impact of lead and hemoglobin levels on children's intelligence.
Main Methods:
- 708 children aged 3-7 in Chennai, India, were assessed for intelligence quotient (IQ) using the Binet-Kamath Scale.
- Blood lead and hemoglobin levels were measured, and TF C2 polymorphism (rs1049296) was genotyped.
- Statistical models explored interactions between lead, hemoglobin, and TF C2 variants.
Main Results:
- Among children with the TF C2 variant, increased blood lead was associated with a significant decrease in IQ (-77 points), while higher hemoglobin showed a smaller positive association (+17 IQ points).
- Children with the homozygous wildtype allele showed less pronounced IQ changes with similar increments in lead (-21 IQ points) and hemoglobin (+28 IQ points).
- Significant interactions were observed between lead and hemoglobin with the TF C2 variant (p=0.04 for lead).
Conclusions:
- The transferrin C2 variant may heighten children's vulnerability to lead-induced neurotoxicity.
- Higher hemoglobin levels might offer less protection against lead's cognitive effects in children carrying the TF C2 variant.
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