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Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism
BACKGROUND: Anemia and lead exposure remain significant public health issues in many parts of the world, often occurring together. Animal studies suggest that the dopamine D2 receptor (DRD2) mediates the effects of both lead and iron on cognition and behavior. OBJECTIVE: We tested the hypothesis tha...
Autores principales: | , , , , , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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National Institute of Environmental Health Sciences
2011
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3018494/ https://www.ncbi.nlm.nih.gov/pubmed/21205584 http://dx.doi.org/10.1289/ehp.0901878 |
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author | Roy, Ananya Hu, Howard Bellinger, David C. Mukherjee, Bhramar Modali, Rama Nasaruddin, Khaja Schwartz, Joel Wright, Robert O. Ettinger, Adrienne S. Palaniapan, Kavitha Balakrishnan, Kalpana |
author_facet | Roy, Ananya Hu, Howard Bellinger, David C. Mukherjee, Bhramar Modali, Rama Nasaruddin, Khaja Schwartz, Joel Wright, Robert O. Ettinger, Adrienne S. Palaniapan, Kavitha Balakrishnan, Kalpana |
author_sort | Roy, Ananya |
collection | PubMed |
description | BACKGROUND: Anemia and lead exposure remain significant public health issues in many parts of the world, often occurring together. Animal studies suggest that the dopamine D2 receptor (DRD2) mediates the effects of both lead and iron on cognition and behavior. OBJECTIVE: We tested the hypothesis that the DRD2 Taq IA polymorphism modifies the effects of lead and hemoglobin on intelligence quotient (IQ) among children. METHODS: Blood lead and hemoglobin were assessed in 717 children 3–7 years of age attending 12 schools in Chennai, India. IQ was determined using the Binet-Kamat scales of intelligence. Genotyping for the DRD2 polymorphism was carried out using a MassARRAY iPLEX platform. Stratified analyses and interaction models, using generalized estimating equations (GEEs), were used to explore interactions between lead and hemoglobin, and DRD2 Taq IA categories [homozygous variant (A1) vs. presence of wild-type allele (A2)]. RESULTS: After we controlled for potential confounders, a one-unit increase in log blood lead was associated with a decrease of 9 IQ points [95% confidence interval (CI), −18.08 to −0.16] in the homozygous-variant children (n = 73) compared with a decrease of 4 IQ points (95% CI, −7.21 to −0.69) among those with the wild-type allele (n = 644). Higher hemoglobin levels were associated with higher IQ in the children who carried the wild-type allele DRD2, but in children homozygous for the variant allele, an increase of 1 g/dL hemoglobin was associated with a decrease in 1.82 points of IQ (95% CI, −5.28 to 1.64; interaction term p-value = 0.02). CONCLUSION: The results of this study suggest that the DRD2 Taq IA polymorphism disrupts the protective effect of hemoglobin on cognition and may increase the susceptibility to the deficits in IQ due to lead exposure. |
format | Text |
id | pubmed-3018494 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2011 |
publisher | National Institute of Environmental Health Sciences |
record_format | MEDLINE/PubMed |
spelling | pubmed-30184942011-02-10 Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism Roy, Ananya Hu, Howard Bellinger, David C. Mukherjee, Bhramar Modali, Rama Nasaruddin, Khaja Schwartz, Joel Wright, Robert O. Ettinger, Adrienne S. Palaniapan, Kavitha Balakrishnan, Kalpana Environ Health Perspect Research BACKGROUND: Anemia and lead exposure remain significant public health issues in many parts of the world, often occurring together. Animal studies suggest that the dopamine D2 receptor (DRD2) mediates the effects of both lead and iron on cognition and behavior. OBJECTIVE: We tested the hypothesis that the DRD2 Taq IA polymorphism modifies the effects of lead and hemoglobin on intelligence quotient (IQ) among children. METHODS: Blood lead and hemoglobin were assessed in 717 children 3–7 years of age attending 12 schools in Chennai, India. IQ was determined using the Binet-Kamat scales of intelligence. Genotyping for the DRD2 polymorphism was carried out using a MassARRAY iPLEX platform. Stratified analyses and interaction models, using generalized estimating equations (GEEs), were used to explore interactions between lead and hemoglobin, and DRD2 Taq IA categories [homozygous variant (A1) vs. presence of wild-type allele (A2)]. RESULTS: After we controlled for potential confounders, a one-unit increase in log blood lead was associated with a decrease of 9 IQ points [95% confidence interval (CI), −18.08 to −0.16] in the homozygous-variant children (n = 73) compared with a decrease of 4 IQ points (95% CI, −7.21 to −0.69) among those with the wild-type allele (n = 644). Higher hemoglobin levels were associated with higher IQ in the children who carried the wild-type allele DRD2, but in children homozygous for the variant allele, an increase of 1 g/dL hemoglobin was associated with a decrease in 1.82 points of IQ (95% CI, −5.28 to 1.64; interaction term p-value = 0.02). CONCLUSION: The results of this study suggest that the DRD2 Taq IA polymorphism disrupts the protective effect of hemoglobin on cognition and may increase the susceptibility to the deficits in IQ due to lead exposure. National Institute of Environmental Health Sciences 2011-01 2010-09-24 /pmc/articles/PMC3018494/ /pubmed/21205584 http://dx.doi.org/10.1289/ehp.0901878 Text en http://creativecommons.org/publicdomain/mark/1.0/ Publication of EHP lies in the public domain and is therefore without copyright. All text from EHP may be reprinted freely. Use of materials published in EHP should be acknowledged (for example, ?Reproduced with permission from Environmental Health Perspectives?); pertinent reference information should be provided for the article from which the material was reproduced. Articles from EHP, especially the News section, may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright. |
spellingShingle | Research Roy, Ananya Hu, Howard Bellinger, David C. Mukherjee, Bhramar Modali, Rama Nasaruddin, Khaja Schwartz, Joel Wright, Robert O. Ettinger, Adrienne S. Palaniapan, Kavitha Balakrishnan, Kalpana Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism |
title | Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism |
title_full | Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism |
title_fullStr | Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism |
title_full_unstemmed | Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism |
title_short | Hemoglobin, Lead Exposure, and Intelligence Quotient: Effect Modification by the DRD2 Taq IA Polymorphism |
title_sort | hemoglobin, lead exposure, and intelligence quotient: effect modification by the drd2 taq ia polymorphism |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3018494/ https://www.ncbi.nlm.nih.gov/pubmed/21205584 http://dx.doi.org/10.1289/ehp.0901878 |
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