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DHA intake interacts with ELOVL2 and ELOVL5 genetic variants to influence polyunsaturated fatty acids in human milk

2019; Elsevier BV; Volume: 60; Issue: 5 Linguagem: Inglês

10.1194/jlr.m090951

ISSN

1539-7262

Autores

Yixia Wu霞吴义, Yan Wang 烟王, Huimin Tian敏田慧, Tong Lu逯通, Miao Yu苗于, Wenhui Xu慧徐文, Guoliang Liu良刘国, Lin Xie林谢,

Tópico(s)

Infant Nutrition and Health

Resumo

Endogenous synthesis of PUFAs is mediated by genes controlling fatty acid elongases 2 and 5 (ELOVL2 and ELOVL5) and by exogenous DHA intake. Associations between elongases and PUFA levels probably involve genetic variants of ELOVL and changes in DHA intake, but data about their combined effect on PUFA levels are sparse. We hypothesized that each factor would directly affect PUFAs and that interactions between haplotypes and DHA intake would influence PUFAs. We explored four levels of DHA intake in pregnant Chinese Han women and 10 SNPs in the ELOVL genes to determine associations with PUFAs in breast milk. The SNP rs3798713 and 3-SNP haplotype (rs2281591, rs12332786, and rs3798713) in ELOVL2 were associated with linoleic acid (LA) concentrations. However, carriers of the 3-SNP haplotype with higher DHA intake (second quartile: 14.58–43.15 mg/day) had higher concentrations of LA, arachidonic acid, EPA, and DHA compared with the interaction baseline. In ELOVL5, five SNPs (rs2294867, rs9357760, rs2397142, rs209512, and rs12207094) correlated with PUFA changes. Compared with those who had the 5-SNP haplotype C-A-C-G-A and low DHA intake (<14.58 mg/day), carriers with other haplotypes (A-A-C-A-A or C-A-C-A-A) and high DHA intake (≥118.82 mg/day) had increased EPA levels after adjustments for age and BMI. This study showed that maternal genetic variants in ELOVL2 and ELOVL5 were associated with PUFA levels in breast milk and that the combination of SNP haplotypes and higher DHA intake increased PUFA concentrations. Endogenous synthesis of PUFAs is mediated by genes controlling fatty acid elongases 2 and 5 (ELOVL2 and ELOVL5) and by exogenous DHA intake. Associations between elongases and PUFA levels probably involve genetic variants of ELOVL and changes in DHA intake, but data about their combined effect on PUFA levels are sparse. We hypothesized that each factor would directly affect PUFAs and that interactions between haplotypes and DHA intake would influence PUFAs. We explored four levels of DHA intake in pregnant Chinese Han women and 10 SNPs in the ELOVL genes to determine associations with PUFAs in breast milk. The SNP rs3798713 and 3-SNP haplotype (rs2281591, rs12332786, and rs3798713) in ELOVL2 were associated with linoleic acid (LA) concentrations. However, carriers of the 3-SNP haplotype with higher DHA intake (second quartile: 14.58–43.15 mg/day) had higher concentrations of LA, arachidonic acid, EPA, and DHA compared with the interaction baseline. In ELOVL5, five SNPs (rs2294867, rs9357760, rs2397142, rs209512, and rs12207094) correlated with PUFA changes. Compared with those who had the 5-SNP haplotype C-A-C-G-A and low DHA intake (<14.58 mg/day), carriers with other haplotypes (A-A-C-A-A or C-A-C-A-A) and high DHA intake (≥118.82 mg/day) had increased EPA levels after adjustments for age and BMI. This study showed that maternal genetic variants in ELOVL2 and ELOVL5 were associated with PUFA levels in breast milk and that the combination of SNP haplotypes and higher DHA intake increased PUFA concentrations. PUFAs, especially LC-PUFAs, are essential nutrients that are associated with the development of the human brain and neurotransmitter function (1.Lauritzen L. Sorensen L.B. Harslof L.B. Ritz C. Stark K.D. Astrup A. Mendelian randomization shows sex-specific associations between long-chain PUFA-related genotypes and cognitive performance in Danish schoolchildren.Am. J. Clin. Nutr. 2017; 106: 88-95Crossref PubMed Scopus (19) Google Scholar, 2.Lauritzen L. Brambilla P. Mazzocchi A. Harslof L.B. Ciappolino V. Agostoni C. DHA effects in brain development and function.Nutrients. 2016; 8: E6Crossref PubMed Scopus (263) Google Scholar, 3.Campoy C. Escolano-Margarit M.V. Anjos T. Szajewska H. Uauy R. Omega 3 fatty acids on child growth, visual acuity and neurodevelopment.Br. J. 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The effect of maternal omega-3 (n-3) LCPUFA supplementation during pregnancy on early childhood cognitive and visual development: a systematic review and meta-analysis of randomized controlled trials.Am. J. Clin. Nutr. 2013; 97: 531-544Crossref PubMed Scopus (163) Google Scholar). Pregnant women who consumed high amounts of n-3 LC-PUFAs in their diet showed positive effects on pregnancy outcomes, such as longer gestational duration and greater birth weight (11.Carlson S.E. Colombo J. Gajewski B.J. Gustafson K.M. Mundy D. Yeast J. Georgieff M.K. Markley L.A. Kerling E.H. Shaddy D.J. DHA supplementation and pregnancy outcomes.Am. J. Clin. Nutr. 2013; 97: 808-815Crossref PubMed Scopus (221) Google Scholar). Additionally, LC-PUFAs may increase infant growth and enhance the short- and long-term development of the offspring (11.Carlson S.E. Colombo J. Gajewski B.J. Gustafson K.M. Mundy D. Yeast J. Georgieff M.K. Markley L.A. Kerling E.H. Shaddy D.J. DHA supplementation and pregnancy outcomes.Am. J. Clin. Nutr. 2013; 97: 808-815Crossref PubMed Scopus (221) Google Scholar, 12.Olsen S.F. Joensen H.D. High liveborn birth weights in the Faroes: a comparison between birth weights in the Faroes and in Denmark.J. Epidemiol. Community Health. 1985; 39: 27-32Crossref PubMed Scopus (82) Google Scholar, 13.Leventakou V. Roumeliotaki T. Martinez D. Barros H. Brantsaeter A.L. Casas M. Charles M.A. Cordier S. Eggesbo M. van Eijsden M. et al.Fish intake during pregnancy, fetal growth, and gestational length in 19 European birth cohort studies.Am. J. Clin. Nutr. 2014; 99: 506-516Crossref PubMed Scopus (83) Google Scholar). A randomized controlled trial showed that supplementation with n-3 LC-PUFAs in the third trimester of pregnancy reduced the absolute risk of persistent wheeze or asthma and infections of the lower respiratory tract in offspring (14.Bisgaard H. Stokholm J. Chawes B.L. Vissing N.H. Bjarnadóttir E. Schoos A.M. Wolsk H.M. Pedersen T.M. Vinding R.K. Thorsteinsdóttir S. Fish oil-derived fatty acids in pregnancy and wheeze and asthma in offspring.N. Engl. J. Med. 2016; 375: 2530-2539Crossref PubMed Scopus (282) Google Scholar). The fetus is mainly supplied with LC-PUFAs by transfer from the maternal circulation via the placenta (15.Duttaroy A.K. Transport of fatty acids across the human placenta: a review.Prog. Lipid Res. 2009; 48: 52-61Crossref PubMed Scopus (221) Google Scholar). Therefore, an adequate supply of LC-PUFAs during pregnancy is critical for fetal life onward. Elongation of LC-PUFAs in the n-3 family is made possible by enzymes called elongases, which are encoded by the elongation of a very long-chain fatty acid (ELOVL) gene family on chromosome 6. Elongases catalyze the elongation of aliphatic carbon chains leading to the formation of LC-PUFAs (16.Jakobsson A. Westerberg R. Jacobsson A. Fatty acid elongases in mammals: their regulation and roles in metabolism.Prog. Lipid Res. 2006; 45: 237-249Crossref PubMed Scopus (635) Google Scholar, 17.Barman M. Nilsson S. Torinsson Naluai A. Sandin A. Wold A.E. Sandberg A.S. Single nucleotide polymorphisms in the FADS gene cluster but not the ELOVL2 gene are associated with serum polyunsaturated fatty acid composition and development of allergy (in a Swedish birth cohort).Nutrients. 2015; 7: 10100-10115Crossref PubMed Scopus (22) Google Scholar). Fatty acid elongases 2 and 5, encoded by the ELOVL2 (6p24.2) and ELOVL5 (6p12.1) genes, respectively, are involved in LC-PUFA synthesis. Plasma percentages of n-3 LC-PUFAs have been shown to be associated with SNPs in ELOVL2 (18.Lemaitre R.N. Tanaka T. Tang W. Manichaikul A. Foy M. Kabagambe E.K. Nettleton J.A. King I.B. Weng L.C. Bhattacharya S. et al.Genetic loci associated with plasma phospholipid n-3 fatty acids: a meta-analysis of genome-wide association studies from the CHARGE Consortium.PLoS Genet. 2011; 7: e1002193Crossref PubMed Scopus (267) Google Scholar) and ELOVL5 (19.Li X. Gan Z.W. Ding Z. Wu Y.X. Chen X.Y. Tian H.M. Liu G.L. Yang Y.T. Xie L. Genetic variants in the ELOVL5 but not ELOVL2 gene associated with polyunsaturated fatty acids in Han Chinese breast milk.Biomed. Environ. Sci. 2017; 30: 64-67PubMed Google Scholar, 20.Morales E. Bustamante M. Gonzalez J.R. Guxens M. Torrent M. Mendez M. Garcia-Esteban R. Julvez J. Forns J. Vrijheid M. et al.Genetic variants of the FADS gene cluster and ELOVL gene family, colostrums LC-PUFA levels, breastfeeding, and child cognition.PLoS One. 2011; 6: e17181Crossref PubMed Scopus (98) Google Scholar), and the enzyme activities are influenced by SNPs within the ELOVL gene family after n-3 LC-PUFA supplementation (21.Alsaleh A. Maniou Z. Lewis F.J. Hall W.L. Sanders T.A. O'Dell S.D. ELOVL2 gene polymorphisms are associated with increases in plasma eicosapentaenoic and docosahexaenoic acid proportions after fish oil supplement.Genes Nutr. 2014; 9: 362Crossref PubMed Scopus (33) Google Scholar, 22.Cormier H. Rudkowska I. Lemieux S. Couture P. Julien P. Vohl M.C. Effects of FADS and ELOVL polymorphisms on indexes of desaturase and elongase activities: results from a pre-post fish oil supplementation.Genes Nutr. 2014; 9: 437Crossref PubMed Scopus (41) Google Scholar). The mechanisms underlying the observed associations between elongases and PUFA levels are inconsistent but probably involve genetic variants within ELOVL and changes in levels of DHA intake. Consequently, we hypothesized that ELOVL polymorphisms and DHA intake would each be directly associated with PUFA concentrations. We also hypothesized that the interactions of haplotypes within ELOVL2 and ELOVL5 with DHA consumption during pregnancy may influence PUFA concentration in the breast milk of healthy lactating Chinese Han women. We recruited 422 healthy Chinese Han pregnant women, 22–40 years of age, who registered for postpartum care at Shirentang House in Changchun from March 2012 to December 2014. Only participants with no maternal pregnancy complications were included. Other exclusion criteria included metabolic diseases (including diabetes) and communicable diseases. The sample size varied from a total of 422 participating women to 420 in analyses of ELOVL SNP versus breast-milk PUFAs as one outcome and from 422 to 370 in analyses of DHA intake versus breast-milk PUFAs as another outcome. All participants gave informed consent according to the procedures approved by the ethics committee of Jilin University. The study abided by the Declaration of Helsinki principles. We gave each participant a face-to-face interview and a semistructured food-frequency questionnaire. The questionnaire was used to assess the dietary intake of enrolled subjects during their pregnancy. It included specific questions about the consumption of sources containing DHA, such as freshwater fish, seafood, and canned tuna. To better understand the data of DHA intake, in the interview, we also asked participants the DHA supplement's brand, the supplementing time, and daily doses. The investigators checked the content of DHA in supplements and calculated the daily doses of DHA of the enrolled subjects. Five kinds of PUFA dietary intakes were calculated based on Yang (23.Yang Y.X. China Food Composition.2nd edition. Beijing University Medical Press, Beijing, China2009Google Scholar). In addition, DHA dietary intakes were calculated as milligrams per day. Twenty milliliters of breast milk were collected between 9:00 AM and 11:00 AM between the 22nd and 25th day after delivery. The first few drops of milk were discarded, and then the mature breast milk was collected. The samples were stored at −80°C (24.Innis S.M. Gilley J. Werker J. Are human milk long-chain polyunsaturated fatty acids related to visual and neural development in breast-fed term infants?.J. Pediatr. 2001; 139: 532-538Abstract Full Text Full Text PDF PubMed Scopus (157) Google Scholar) for approximately 1 month. The levels of eight kinds of fatty acids in breast milk were determined by direct methylation (25.Lepage G. Roy C.C. Direct transesterification of all classes of lipids in a one-step reaction.J. Lipid Res. 1986; 27: 114-120Abstract Full Text PDF PubMed Google Scholar) with subsequent analysis by gas chromatography-flame ionization detection. A GC-14B gas chromatograph (Shimadzu Corp., Kyoto, Japan) was equipped with an sp-2560 capillary column (100 m × 0.25 mm × 0.20 μ Supelco, Bellefonte, PA). The internal standard method was used to calculate the levels of fatty acid methyl esters. Fatty acid methyl esters were prepared from milk by combining 0.2 ml fat with 2 ml methanol and benzene (4:1; v/v), 33 µl internal standard (daturic acid, C17:0), and 200 µl acetyl chloride in a 10 ml glass tube. Specific experimental steps have been described previously (26.Ding Z. Liu G.L. Li X. Chen X.Y. Wu Y.X. Cui C.C. Zhang X. Yang G. Xie L. Association of polyunsaturated fatty acids in breast milk with fatty acid desaturase gene polymorphisms among Chinese lactating mothers.Prostaglandins Leukot. Essent. Fatty Acids. 2016; 109: 66-71Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar). SNPs in ELOVL2 and ELOVL5 were identified using the International HapMap Project SNP database and the NCBI database (http://www.ncbi.nlm.nih.gov/snp). Selected SNPs of the ELOVL gene cluster (rs2281591, rs12332786, rs3798713, rs3778166, rs9468304, rs2294867, rs9357760, rs2397142, rs209512, rs12207094) have been genotyped using the Sequenom MassARRAY system (BO MIAO Biological Technological Co., Beijing, China) with validated primers, and the genotyping success rate was above 96%. ELOVL2 and ELOVL5 are located on chromosome 6 (10.99–11.05 Mb and 53.28–53.34 Mb, respectively), and the selected SNPs are all intron variants. Each SNP has a minor allele frequency above 10% in the Asian population according to the SNP database of the NCBI. The milk samples were thawed at 4°C, and genomic DNA was extracted from 300 µl of the cellular layer using a DNA kit (TIANGEN, Beijing, China) according to the manufacturer's instructions. Normal distribution of the fatty acids was tested by the Kolmogorov-Smirnov test and distribution plots. Data were expressed as means ± SDs for normal distributed variables and as medians (25th to 75th percentiles) for skewed distribution data. The skewed measurements of γ-linolenic acid (GLA; 18:3n-6), EPA (20:5n-3), and DHA concentrations were expressed as square roots to obtain a normal distribution. Hardy-Weinberg equilibrium was tested by a Chi-square goodness-of-fit test for each SNP locus. The genotype association with PUFA concentrations was tested using SNPstats software (https://www.snpstats.net/start.htm). Linear-regression analysis was used to investigate the associations of ELOVL gene polymorphisms with levels of PUFAs. Statistical analysis was performed using SPSS version 16.0 (SPSS Inc., Chicago, IL). Haplotype analyses play an important role in genetic studies (27.Schaid D.J. Evaluating associations of haplotypes with traits.Genet. Epidemiol. 2004; 27: 348-364Crossref PubMed Scopus (258) Google Scholar, 28.Tzeng J.Y. Wang C.H. Kao J.T. Hsiao C.K. Regression-based association analysis with clustered haplotypes through use of genotypes.Am. J. Hum. Genet. 2006; 78: 231-242Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). It is impossible to define the combination of haplotypes carried by any one individual, but all possible combinations can be computed, and techniques such as the EM algorithm incorporated in the haplo.stats package of R software (https://cran.r-project.org/src/contrib/Archive/haplo.stats) can be used to assign a probability to each haplotype pair. To explore potential effects of multi-SNP and DHA intake, the interactions between the ELOVL2/5 haplotype and DHA intake on LC-PUFA levels were performed by the general linear model using R software version 3.5.0 adjusted for confounding factors. P< 0.05 (two-tailed) was considered statistically significant. The 422 healthy lactating mothers included in this study had an average age of 30.29 ± 3.40 years and mainly came from middle-income households (54.09%). Gestational age was 39.27 ± 1.00 weeks. The preconception BMI was 20.95 ± 3.33 kg/m2, which was within the normal range. A total of 31.10% of subjects had a vaginal delivery, while the rest had cesareans. A total of 54.39% of the subject breastfed exclusively, while the remaining 45.61% opted for mixed feeding. A total of 50.75% of the mothers had a university education (Table 1).TABLE 1.Background characteristics of the lactating mothersVariableValueAge (years)30.29 ± 3.40Gestational age (weeks)39.27 ± 1.00Preconception BMI (kg/m2)20.95 ± 3.33Gestational weight gain (kg)18.88 ± 6.30Feeding patterns [n(%)]Exclusive breastfeeding223 (54.39)Mixed feeding187 (45.61)Delivery patterns [n (%)]Vaginal130 (31.10)Cesarean288 (68.90)Education level [n (%)]Graduate school37 (9.25)University203 (50.75)High school140 (35.00)Middle school17 (4.25)Primary school3 (0.75)Household income [n (%)]Low57 (16.67)Middle185 (54.09)High100 (29.24) Open table in a new tab We investigated the effect of DHA intake (including dietary and supplemental DHA) during pregnancy on the concentration of eight PUFAs in breast milk and sought to determine whether there was a dose-response relationship. The lactating mothers were classified into four subgroups depending on the quartiles of DHA intake (Q1: < 14.58; Q2: 14.58–43.15; Q3: 43.16–118.82; and Q4: ≥118.82 mg/day) (Table 2). However, the results showed that there was no significant difference for PUFA composition of breast milk among the four groups.TABLE 2.Association between DHA intake and breast-milk PUFAs by quartile of DHA intakePUFAs (g/100 g)DHA intake (mg/day)PQ1 ( 0.05). The selected SNPs were all in introns, and the genotyping success rate was >96%. The characteristics of the detected SNPs, including their positions on chromosome 6 and their genotypes, are summarized in Table 3. Minor allele frequencies ranged from ∼10.7% to 46.8% of the population.TABLE 3.Characteristics of 10 polymorphisms in the ELOVL gene clusterGeneSNPPosition (bp)AllelesGenotypeaNumber of women carrying MM, Mm, or mm.AllelebNumber of women carrying M or m.Genotyping Success Rate (%)M/mMMMmmmMmELOVL2rs228159110990260A/G2641352166317799.53rs1233278610998735C/G2361602463220899.53rs379871311008389C/G1801864554627697.39rs377816611032931G/A1312067946836498.58rs946830411041932A/G2071714158525399.29ELOVL5rs229486753289156C/A1561866649831896.68rs935776053325336A/G1831795054527997.63rs239714253335501C/G1861774454926796.45rs20951253338779A/G1142178744539199.05rs1220709453339377A/T3358247509099.76M, major allele; m, minor allele; MM, major allele homozygote; mm, minor allele homozygote; Mm, heterozygote.a Number of women carrying MM, Mm, or mm.b Number of women carrying M or m. Open table in a new tab M, major allele; m, minor allele; MM, major allele homozygote; mm, minor allele homozygote; Mm, heterozygote. The association of three genetic models (codominant, dominant, and recessive) for each of the 10 SNPs with breast-milk PUFAs was analyzed using SNPstats software and adjusted for age, preconception BMI, and DHA intake of subjects. The best-fit genetic model of the 10 SNPs was chosen based on the Akaike information criterion and Bayesian information criterion (Fig. 1). Carriers of the minor allele of rs3798713 (P= 0.019) in the ELOVL2 gene had lower linoleic acid (LA; 18:2n-6) concentrations of breast milk than homozygous subjects for the major allele. The subjects carrying the minor allele homozygote of rs2294867 (P= 0.036) within ELOVL5 had higher EPA concentrations than those who carried the major allele. Subjects who carried the minor allele of rs9357760 in the ELOVL5 gene had higher GLA (P= 0.043), dihomo-γ-linolenic acid (DGLA; 20:3n-6) (P= 0.013), arachidonic acid (ARA; 20:4n-6) (P= 0.014), and docosatetraenoic acid (DTA; 22:4n-6) (P= 0.009) concentrations than homozygotes for the major allele. Carriers of the minor allele of rs2397142 had higher DTA levels compared with homozygotes for the major allele (P= 0.027). The subjects homozygous for the minor allele of rs209512 had lower GLA (P= 0.042) and DGLA (P= 0.039) concentrations than those carrying the major allele. A significant association was also observed between rs12207094 (P= 0.029) in ELOVL5 and the level of GLA; carriers of the minor allele had higher levels compared with homozygotes for the major allele. However, no statistically significant differences were found between the other SNPs and fatty acid levels. The full details of the analytical results are provided in supplemental Table S1. The results of the ELOVL2 and ELOVL5 haplotype frequencies can be found in supplemental Tables S2 and S3. Table 4 shows that a 3-SNP haplotype (H2: A-G-G) in ELOVL2 (rs2281591 A/G, rs12332786 C/G, and rs3798713 C/G) was associated with a decline in LA (P= 0.046), EPA (P= 0.022), and DHA (P= 0.008) concentrations in breast milk compared with carriers of the baseline haplotype (H1: A-C-C) after adjusting for age and BMI. However, we found that the interaction of haplotype H2 with the second quartile of DHA intake (Q2: 14.58–43.15 mg/day) increased the concentration of LA (P= 0.038), ARA (P= 0.025), EPA (P= 0.034), and DHA (P= 0.004) compared with carriers of haplotype H1 with low DHA intake (Q1: <14.58 mg/day) after adjusting for age and BMI.TABLE 4.Interaction between ELOVL2/5 haplotype and DHA intake on breast-milk PUFA levelLAGLADGLAARADTAALAEPADHAcoefPcoefPcoefPcoefPcoefPcoefPcoefPcoefPELOVL2Q1aQuartile level of DHA intake. Q1: < 14.58 mg/day (reference); Q2: 14.58–43.15 mg/day; and Q4: ≥118.82 mg/day.ReferenceQ2aQuartile level of DHA intake. Q1: < 14.58 mg/day (reference); Q2: 14.58–43.15 mg/day; and Q4: ≥118.82 mg/day.−0.02430.644−0.01610.344−0.00470.567−0.00530.635−0.00120.654−0.00990.643−0.00840.333−0.00310.876H1bType of haplotype. ELOVL2, H1: A-C-C (reference); ELOVL2, H2: A-G-G; ELOVL5, H1: C-A-C-G-A (reference); ELOVL5, H4: A-A-C-A-A; and ELOVL5, H5: C-A-C-A-A. Haplotypes are named according to their frequency.ReferenceH2bType of haplotype. ELOVL2, H1: A-C-C (reference); ELOVL2, H2: A-G-G; ELOVL5, H1: C-A-C-G-A (reference); ELOVL5, H4: A-A-C-A-A; and ELOVL5, H5: C-A-C-A-A. Haplotypes are named according to their frequency.−0.07230.046−0.02050.093−0.00650.253−0.01250.107−0.00220.251−0.02530.083−0.01430.022−0.03640.008Q1-H1cEffect of interaction between DHA intake and haplotype on PUFA levels compared with the reference.ReferenceQ2-H2cEffect of interaction between DHA intake and haplotype on PUFA levels compared with the reference.0.11070.0380.03290.0600.01080.1920.02550.0250.00400.1430.03850.0720.01900.0340.05860.004ELOVL5Q1aQuartile level of DHA intake. Q1: < 14.58 mg/day (reference); Q2: 14.58–43.15 mg/day; and Q4: ≥118.82 mg/day.ReferenceQ2aQuartile level of DHA intake. Q1: < 14.58 mg/day (reference); Q2: 14.58–43.15 mg/day; and Q4: ≥118.82 mg/day.−0.01440.790−0.01440.406−0.00230.7800.00050.967−0.00040.891−0.03270.128−0.01020.246−0.01930.342Q4aQuartile level of DHA intake. Q1: < 14.58 mg/day (reference); Q2: 14.58–43.15 mg/day; and Q4: ≥118.82 mg/day.−0.04500.374−0.01260.437−0.00720.345−0.01360.204−0.00240.351−0.02230.267−0.00200.8120.00360.851H1bType of haplotype. ELOVL2, H1: A-C-C (reference); ELOVL2, H2: A-G-G; ELOVL5, H1: C-A-C-G-A (reference); ELOVL5, H4: A-A-C-A-A; and ELOVL5, H5: C-A-C-A-A. Haplotypes are named according to their frequency.ReferenceH4bType of haplotype. ELOVL2, H1: A-C-C (reference); ELOVL2, H2: A-G-G; ELOVL5, H1: C-A-C-G-A (reference); ELOVL5, H4: A-A-C-A-A; and ELOVL5, H5: C-A-C-A-A. Haplotypes are named according to their frequency.−0.05460.376−0.02800.157−0.00980.295−0.01450.264−0.00400.205−0.01310.595−0.01680.095−0.03290.157H5bType of haplotype. ELOVL2, H1: A-C-C (reference); ELOVL2, H2: A-G-G; ELOVL5, H1: C-A-C-G-A (reference); ELOVL5, H4: A-A-C-A-A; and ELOVL5, H5: C-A-C-A-A. Haplotypes are named according to their frequency.−0.00860.8860.00810.6720.00310.736−0.00430.735−0.00110.721−0.00340.886−0.01060.273−0.01720.473Q1-H1cEffect of interaction between DHA intake and haplotype on PUFA levels compared with the reference.ReferenceQ2-H4cEffect of interaction between DHA intake and haplotype on PUFA levels compared with the reference.0.03410.6990.02130.4550.00300.8290.00930.6150.00030.9530.06790.0530.00720.6110.04340.185Q4-H4cEffect of interaction between DHA intake and haplotype on PUFA levels compared with the reference.0.19940.0680.06030.0840.03850.0200.03260.1590.00460.4090.09980.0220.03590.0420.06210.129Q2-H5cEffect of interaction between DHA intake and haplotype on PUFA levels compared with the reference.0.11580.2380.02500.4520.03180.0360.03820.0690.00830.0990.05270.1820.04240.0110.05500.141Q4-H5cEffect of interaction between DHA intake and haplotype on PUFA levels compared with the reference.−0.00680.9440.04460.1620.00590.6940.00290.8870.00200.695−0.00550.8850.03930.0150.06000.124a Quartile level of DHA intake. Q1: < 14.58 mg/day (reference); Q2: 14.58–43.15 mg/day; and Q4: ≥118.82 mg/day.b Type of haplotype. ELOVL2, H1: A-C-C (reference); ELOVL2, H2: A-G-G; ELOVL5, H1: C-A-C-G-A (reference); ELOVL5, H4: A-A-C-A-A; and ELOVL5, H5: C-A-C-A-A. Haplotypes are named according to their frequency.c Effect of interaction between DHA intake and haplotype on PUFA levels compared with the reference. Open table in a new tab Compared with those who had a 5-SNP haplotype (H1: C-A-C-G-A) (rs2294867 C/A, rs9357760 A/G, rs2397142 C/G, rs209512 A/G, and rs12207094A/T) in ELOVL5 with low DHA intake (Q1), carriers with the haplotype H4: A-A-C-A-A who consumed high levels of DHA (Q4: ≥118.82 mg/day) had higher levels of DGLA, α-linolenic acid (ALA; 18:3n-3), and EPA (P= 0.020, P= 0.022, and P= 0.042, respectively) in breast milk after adjusting for age and BMI. Another interaction between the haplotype H5: C-A-C-A-A and DHA intake (Q2) increased DGLA and EPA concentrations (P= 0.036 and P= 0.011, respectively). Likewise, haplotype H5 interacting with

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