rs2072114 — FADS2 FADS2 Intron 1 Variant

FADS2 Intron 1 Variant — Delta-6 Desaturase Activity and Fatty Acid Balance

The FADS2 gene encodes delta-6 desaturase¹¹ delta-6 desaturase
delta-6 desaturase (D6D) is the rate-limiting enzyme in the conversion of linoleic acid (LA) and alpha-linolenic acid (ALA) to their longer-chain products, the gateway enzyme controlling how your body converts essential fatty acids from food into the biologically active long-chain polyunsaturated fatty acids (LC-PUFAs) — including arachidonic acid (AA), EPA, and DHA. rs2072114 is an intronic SNP in the first intron of FADS2, sitting within the broader FADS1/FADS2 haplotype block²² FADS1/FADS2 haplotype block
A haplotype block is a stretch of DNA where nearby variants tend to be inherited together as a unit on chromosome 11q12-13. Though non-coding, it serves as a reliable tag for functional variation in this cluster that modulates desaturase enzyme output.

The Mechanism

Delta-6 desaturase performs the first and most critical step in converting short-chain dietary omega-6 and omega-3 fatty acids into their longer, more bioactive derivatives. For omega-6s: LA → GLA → DGLA → AA. For omega-3s: ALA → SDA → EPA → DHA. The G allele of rs2072114 is associated with altered n-6 desaturase activity — the direction of effect (increased or decreased) is population- and sex-specific, reflecting interactions between genetic background and hormonal environment. In populations studied, the net result tends to shift fatty acid profiles toward lower arachidonic acid production relative to linoleic acid precursor, and may reduce delta-5 and delta-6 desaturase efficiency for certain conversions in specific subgroups.

Because rs2072114 lies within a strong linkage disequilibrium block, its observed associations partly reflect correlated effects of neighboring functional FADS2 variants (rs174575, rs174576, rs174602) rather than a direct effect of the intronic position itself.

The Evidence

A cross-sectional study by Abdelmagid et al.³³ cross-sectional study by Abdelmagid et al.
Abdelmagid et al. Ethnicity, sex, FADS genetic variation, and hormonal contraceptive use influence delta-5- and delta-6-desaturase indices and plasma DHA concentration in young Canadian adults. Nutr Metab, 2015 of 787 Caucasian and East Asian young adults found that rs2072114 was significantly associated with aggregate n-6 desaturase indices, with effects that were ethnicity- and sex-specific. East Asian females showed the most pronounced associations after multiple-testing correction.

A Taiwanese clinical study by Huang et al.⁴⁴ Taiwanese clinical study by Huang et al.
Huang et al. Interaction among dietary n-3 and n-6 PUFA intake, FADS2 genetic variants, and LDL-C in type 2 diabetes patients. J Diabetes Investig, 2023 in 816 type 2 diabetes patients found that the G allele of rs2072114 showed a significant gene-diet interaction (P = 0.016): among individuals with a low alpha-linolenic acid/linoleic acid ratio in their diet, G allele carriers had lower LDL-C concentrations. This suggests the metabolic effect of this variant is diet-sensitive and most pronounced when omega-3 dietary intake is relatively low.

Broader evidence for the FADS1/FADS2 locus⁵⁵ FADS1/FADS2 locus
Tanaka et al. GWAS of plasma PUFA in InCHIANTI study. PLoS Genet, 2009 confirms this genomic region is the dominant genetic determinant of circulating PUFA levels — the lead SNP rs174537 explains 18.6% of variance in arachidonic acid concentrations. rs2072114 tags this same haplotype block.

Practical Actions

The G allele's effect on fatty acid desaturation is context-dependent. The most robust intervention is ensuring a dietary n-3/n-6 ratio that limits the functional impact of reduced conversion efficiency. G allele carriers benefit from increasing preformed EPA and DHA from marine or algae-based sources, rather than relying solely on ALA conversion from plant oils. Monitoring lipid panels — particularly LDL-C in the context of dietary fatty acid composition — gives personalized feedback on whether the genetic effect is clinically active.

Interactions

rs2072114 sits within the same haplotype block as rs174547 (FADS1) and rs174575, rs174576, rs174602 (FADS2). Carriers of multiple variant alleles across this cluster may have additive reductions in both delta-5 and delta-6 desaturase activity, amplifying the need for preformed LC-PUFAs. The ELOVL2 gene (rs953413, chromosome 6) is a pathway partner — it handles the elongation step after FADS2 has performed initial desaturation, so combined variation across FADS2 and ELOVL2 can further reduce DHA synthesis efficiency.