Impact of fatty acid desaturase (FADS) genotypes on the relationship between serum lipids and dietary fat intake in young Mexican college students

Vazquez Vidal, Itzel

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https://hdl.handle.net/2142/50342 Copy

Description

Title

Impact of fatty acid desaturase (FADS) genotypes on the relationship between serum lipids and dietary fat intake in young Mexican college students

Author(s)

Vazquez Vidal, Itzel

Issue Date

2014-09-16

Director of Research (if dissertation) or Advisor (if thesis)

Teran-Garcia, Margarita D.

Doctoral Committee Chair(s)

Nakamura, Manabu T.

Committee Member(s)

• Teran-Garcia, Margarita D.
• Chapman-Novakofski, Karen M.
• Garrow, Timothy A.
• Aradillas-Garcia, Celia

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Fatty Acid Desaturase (FADS) gene cluster
• Mexican adolescents
• dyslipidemias

Abstract

ABSTRACT Background: The Mexican population has been found to exhibit an environmental and genetic predisposition to develop blood lipid disorders [1, 2]. The fatty acid desaturase (FADS) gene cluster encodes two key enzymes which are involved in the synthesis of long-chain polyunsaturated fatty acids (PUFA). Delta-5 desaturase (D5D) and Delta-6 desaturase (D6D) are encoded by FADS1 and FADS2, respectively. FADS gene cluster polymorphisms have recently been determined to be associated with high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels in Europeans [3]. Moreover, the dietary intake of PUFAs affects FADS-blood lipids interactions [4]. Gene-nutrient interactions and individual genetic variations of the FADS gene cluster have not been described in young Mexicans to date. Objectives: The first aim was to report genetic associations between FADS1-rs174546 and FADS2-rs1535 polymorphisms and blood lipid profiles in Mexican college-age students. The second aim was to determine whether dietary intake of omega-3 and omega-6 PUFAs modified genetic associations between the FADS gene cluster and lipid profiles. Methods: Body mass indexes (BMI), blood lipid profiles, dietary intakes of omega-3 and omega-6 fatty acids, and genotypes in the FADS gene cluster were evaluated in 462 individuals from the “UP AMIGOS” cohort, aged 18-25 yrs. FADS-SNPs were in Hardy-Weinberg equilibrium with a minor allele frequency of 0.29 and 0.28 for rs174546 and rs1535, respectively. All of the data was analyzed using SAS 9.3 (SAS Institute Inc., NC, USA), assuming a significance level of p<0.05 for multiple comparisons. Non-normal distributed variables were log transformed prior to analysis. The primary analysis was conducted using general linear regression models to examine associations between FADS SNPs and the blood lipid profiles adjusted for sex, age and BMI. A secondary analysis tested the impact of dietary intake of omega-3 (g/d) and omega-6 (g/d) on the association between FADS SNPs and the lipid profiles adjusted for sex, age, BMI and total calorie intake. Results: Carriers of the minor C-allele of FADS1-rs174546 and A-allele of FADS2-rs1535 had significantly higher LDL-C, TC and non-HDL-C concentrations compared with homozygotes for the major allele (T and G alleles, respectively). No significant associations were observed between the FADS genotypes and HDL-C, TG and VLDL concentrations. Moreover, BMI status has a strong impact on the FADS genotype and the lipid profile. Second, a significant association was observed between FADS1/FADS2 and dietary intake of omega-3, but this was not the case for omega-6 with respect to LDL-C levels. In addition, as a categorical variable, carriers of the C-allele were associated with lower LDL-C among those with lower intakes of omega-3. Conclusion: Carriers of the minor allele of FADS1/FADS2 exhibited higher levels of atherogenic lipoproteins such as higher LDL-C. Moreover, FADS polymorphisms interact with dietary omega-3 to effect plasma cholesterol concentrations, which should be investigated further in future studies. Future directions: There has been a documented rapid increase in the prevalence of Mexican college-age students who are overweight and obese coupled with a high prevalence of dyslipidemias [5-9]. We propose a new approach for identifying individuals who are at risk for dyslipidemias. This approach investigates potential gene-nutrient interactions that may provide insight into potential future therapies and dietary intervention strategies for preventing or delaying cardiovascular disease.

Graduation Semester

2014-08

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http://hdl.handle.net/2142/50342

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Copyright 2014 Itzel Vazquez Vidal

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