2004 Progress Report: Genetics of Phthalate and Bisphenol A Risk in Minority Populations (Individual Susceptibility)EPA Grant Number: R831711C003
Subproject: this is subproject number 003 , established and managed by the Center Director under grant R831711
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Mount Sinai Center for Children’s Health and the Environment
Center Director: Wolff, Mary S.
Title: Genetics of Phthalate and Bisphenol A Risk in Minority Populations (Individual Susceptibility)
Investigators: Wetmur, James G.
Current Investigators: Wetmur, James G. , Chen, Jia , Wolff, Mary S.
Institution: Mount Sinai School of Medicine
EPA Project Officer: Callan, Richard
Project Period: November 1, 2003 through October 31, 2008 (Extended to October 31, 2010)
Project Period Covered by this Report: May 7, 2004 through October 31,2004
RFA: Centers for Children's Environmental Health and Disease Prevention Research (2003) RFA Text | Recipients Lists
Research Category: Children's Health , Health Effects , Health
The objective of this research project is to study seven genetic polymorphisms in the enzymes that activate and detoxify organophosphates and other pesticides in the population of mothers and infants enrolled in project R831711C002.
Throughout most of this year we concentrated on finishing up the paraoxonase-1 (PON1) work from the previous 5 years that continues as part of the renewal that was to begin November 1, 2003. Since the funding of the new 5-year grant renewal in April, we have begun to receive saliva samples for the phthalate project. We will be carrying out the enzyme activity assays after we have enough samples in order to obtain simultaneous data and to select samples for QCs. We are also gearing up for genotyping UGT2B7 and lingual lipase.
We have collaborated with Project 2 (R831711C002) in two published manuscripts during the past year:
Chen J, Kumar M, Chan W, Berkowitz G, Wetmur JG. Increased influence of genetic variation on PON1 activity in neonates. Environmental Health Perspectives 2003;111(11):1403-1409.
Berkowitz GS, Wetmur JG, Birman-Deych E, Obel J, Lapinski RH, Godbold JH, Holzman IR, Wolff MS. In utero pesticide exposure, maternal paraoxonase activity, and head circumference. Environmental Health Perspectives 2004;112(3):388-391
and the following abstract:
Chen J, Chan W, Berkowitz G, Wolff M, Wetmur JG. Functional polymorphisms and triglycerides are independent determinants of PON1 enzymatic activity in pregnant women. Presented at the AACR Meeting on SNPs and Cancer, Key Biscayne, FL, 2003.
A manuscript on these data is in preparation.
PON1 is an enzyme found in high-density lipoprotein (HDL) that detoxifies oxidized lipids in HDL and low-density lipoprotein (LDL). It also exhibits an arylesterase activity on organophosphates. The PON1 gene contains five common polymorphisms, three in the promoter [-162, -108 (in linkage disequilibrium with -909)] and two in the coding region (M55L, Q192R) with varying but incomplete linkage disequilibrium. M55L and -108 affect arylesterase activity, and Q192R affects organophosphate substrate specificity. Many studies have associated PON1 polymorphisms with cardiovascular diseases, and a recent study has linked the PON1 Q192R polymorphism with risk of development of non-Hodgkin’s lymphoma (Kerridge, et al., 2002). Our previous studies demonstrated that functional polymorphisms in PON1 were strongly associated with enzymatic activity in both pregnant women (26-30 weeks gestation) and neonates. In the only previous report on maternal PON1 activity, maternal lipids and birth weight, average PON1 activities and serum triglycerides were found to increase during pregnancy, to be highly correlated to one another, and to correlate negatively with birth weight; in our study, however, we were not able to confirm any relationship between PON1 activity or PON1 genes and birth weight. Lipid profiles (HDL, LDL, cholesterol, and triglycerides) were determined for a subset of 117 Caucasian and Hispanic mothers. There was a trend toward higher lipid values in all categories with increasing PON1 activity, approaching the level of significance for cholesterol [p(trend) = 0.08 for PON1 tertiles; p = 0.05 with low PON1 tertile reference value] but highly significant for triglycerides [p(trend) = 0.0008; p = 0.005 with low PON1 tertile reference value]. PON1 polymorphisms explained 19.9 percent of the PON1 variability, while triglycerides explained 4.9 percent; collectively, polymorphisms and triglycerides explained 25.4 percent. The contributions appear to be additive, suggesting triglycerides are an independent determinant of PON1 activity.
Dr. Wetmur also presented these and summary data in an oral presentation on PON1 Genotypes and Phenotypes at the International PON Meeting in Ann Arbor (2004).
We have also presented two abstracts based on this grant and additional funding by the National Institute of Environmental Health Sciences (NIEHS), also described in detail below.
Chen J, Chan W, Majeed F, Berkowitz G, et al. Haplotype—phenotype relationships of PON1. Presented at the AACR Annual Meeting, Orlando, FL, 2004.
PON1 is a metabolizing enzyme found in HDL that metabolizes oxidized lipids and detoxifies organophosphates by cleavage of active oxons that are potential cholinesterase inhibitors in the peripheral and central nervous system. As a result, PON1 is believed to be important in preventing neurotoxic damage and atherosclerosis. The PON1 gene contains five common polymorphisms, three in the promoter (-909G>C, -162A>G, -108C>T) and two in the coding region (M55L, Q192R) with varying but incomplete linkage disequilibrium. M55L and -108 affect arylesterase activity, and Q192R affects organophosphate substrate specificity. Our previous studies demonstrated that single functional polymorphisms in PON1 were strongly associated with enzymatic activity in both pregnant women (26-30 weeks gestation) and neonates. However, unphased genotype (haplotype) information related to heterozygosity at two or more loci may distort the true contributions of each of the single nucleotide polymorphisms (SNPs) to PON1 activity. Recent development in statistical methods has permitted the reconstruction of haplotypes and the estimation of haplotype frequency estimates in unrelated populations based on unphased SNP data. These computationally-based methods may potentially eliminate the need for costly experimental haplotyping methods. These programs use either the maximum-likelihood based expectation-maximization (EM) algorithm or a Bayesian approach to infer haplotypes given the observed genotype data. We used two recently-developed programs, PHASE and tagSNPs, to infer haplotypes for the five common SNPs in the PON1 gene. Inferred haplotypes were then tested for associations with PON1 activity. The study consisted of 402 ethnically-diverse pregnant mothers participating in an on-going study conducted by the Mount Sinai Children’s Environmental Health Center to prospectively assess infant growth and neurodevelopmental risks associated with pesticide exposure in an inner-city population in New York City. Genotypes for the five common SNPs in the PON1 gene and PON1 activity, as measured by phenylacetate hydrolysis, have been determined. Both the PHASE and tagSNPs programs inferred the same seven common haplotypes (estimated frequencies ≥ 5%) with similar frequency. Consistent with population genetics theory, the frequencies of common haplotypes for Hispanics, thought to be a mix of Caucasian African and Amerind ancestry, tend to fall between those for Caucasians and African-Americans. If subjects had more than one possible inferred haplotype pair, only the pair with an estimated probability > 0.70 in phase call accuracy was used for tests of association with PON1 activity. Least-squares means testing with these seven haplotypes indicated that three of these haplotypes were significantly associated with PON1 activity (P < 0.05). A paired t-test with the haplotype containing the –108C>T, -909G>C and the M55L polymorphisms showed that PON1 activity for this haplotype was statistically lower than the activity for the other six commonly-occurring haplotypes combined (mean PON1 activity = 9.14 versus 9.28, respectively, P < 0.0001). Our analyses demonstrate that haplotype information may strengthen the genotype-phenotype relation of PON1.
Wetmur JG, Kumar M, Zhang L, Palomeque C, et al. Molecular haplotyping by linking emulsion PCR: analysis of PON1 haplotypes and phenotypes. Presented at the International Society of Human Genetics Annual Meeting, Toronto, Canada, 2004.
Combining linking PCR with emulsion PCR enables formation of minichromosomes preserving haplotype content. Emulsion PCR confined amplicons of two linked polymorphic sites on a single template molecule to one aqueous-phase droplet. Linking PCR used external primers in excess over biotinylated, overlapping linking primers to connect these amplicons. We removed unlinked amplicons on streptavidin-coated magnetic beads and capped unlinked amplicon runoff products by primer extension on partially complementary 3’-blocked oligonucleotides. Determination of PON1 molecular haplotypes at three loci (-909G>C, L55M, Q192R) in 378 women required quantitative allele-specific PCR measurements of 89, 77, and 68 double heterozygotes for -909G>C/L55M, -909G>C/Q192R and L55M/Q192R, respectively. Promoter polymorphisms (e.g. -909G>C) affect transcription efficiency. The Q192R polymorphism affects PON1 activity ratios with phenylacetate versus paraoxon as substrates. We observed a strong dependence of PON1 activity ratios on -909G>C/ Q192R haplotype. These results demonstrate the power of molecular haplotype analysis for relating phenotype to genotype.
In the coming year, we will be carrying out the lipase assays on a subset of our population and will endeavor to correlate these activities with a chromogenic substrate with phthalate metabolism in the same samples. Population genotyping of UGT2B7 will be initiated.
References:Kerridge I, et al. British Journal of Hematology 2002;118:477.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
|Other subproject views:||All 93 publications||57 publications in selected types||All 52 journal articles|
|Other center views:||All 253 publications||140 publications in selected types||All 118 journal articles|
||Berkowitz GS, Wetmur JG, Birman-Deych E, Obel J, Lapinski RH, Godbold JH, Holzman IR, Wolff MS. In utero pesticide exposure, maternal paraoxonase activity, and head circumference. Environmental Health Perspectives 2004;112(3):388-391.||
||Chen J, Kumar M, Chan W, Berkowitz G, Wetmur JG. Increased influence of genetic variation on PON1 activity in neonates. Environmental Health Perspectives 2003;111(11):1403-1409.||
Supplemental Keywords:lipase, paraoxonase, pesticides, haplotyping technology, polymorphisms, endocrine disruptors, EDs, neurodevelopment, minority populations,, RFA, Health, Scientific Discipline, ENVIRONMENTAL MANAGEMENT, POLLUTANTS/TOXICS, Environmental Chemistry, Health Risk Assessment, Chemicals, Endocrine Disruptors - Environmental Exposure & Risk, endocrine disruptors, Biochemistry, Children's Health, Endocrine Disruptors - Human Health, Risk Assessment, pesticide exposure, environmental health, childhood development, endocrine disrupting chemicals, exposure studies, pesticides, phtalates, Human Health Risk Assessment, genetic polymorphisms, children's vulnerablity, neurodevelopmental toxicity, exposure pathways, children's environmental health
Progress and Final Reports:Original Abstract
Main Center Abstract and Reports:R831711 Mount Sinai Center for Children’s Health and the Environment
Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R831711C001 Growing Up Healthy in East Harlem (Community-Based Participatory Research)
R831711C002 Pesticides, Endocrine Disruptors, Childhood Growth and Development (Birth Cohort)
R831711C003 Genetics of Phthalate and Bisphenol A Risk in Minority Populations (Individual Susceptibility)