Table 1.

Single nucleotide polymorphisms (SNPs) identified from published genome-wide association studies (GWAS) used to construct genetic instruments for polyunsaturated fatty acids (PUFA)

Polyunsaturated fatty acids (chain length)	Number of SNPs used in instrument	% variation Explaineda	1 SD Increase in wGSb (%)	Independent SNPs included in instrumentc
Omega-6
Linoleic acid (LA; 18:2)	4	8.8 – 23.6	1.18	rs10740118, rs174547, rs2727270, rs16966952
Arachidonic acid (AA; 20:2)	2	33.1	1.11	rs174547, rs16966952
Omega-3
α-linolenic acid (ALA; 18:3)	1	1.0	0.01	rs174547
Eicosapentaenoic acid (EPA; 20:5)	2	2.1	0.06	rs3798713, rs174538
Docosapentaenoic acid (DPA; 22:5)	3	11.6	0.06	rs780094, rs3734398, rs174547
Docosahexaenoic acid (DHA; 22:6)	1	0.7	0.08	rs2236212

^aPercent variation explained per instrument calculated as follows: $\sum _i^n{[2{\beta }_i}^2\left(MAF\right)(1-MAF)/\mathit{\text{variance}}\left(\mathit{\text{PUFA}}\right)]*100$, where n is the number of independent SNPs, β is effect estimate from GWAS, MAF is the minor allele frequency, and variance is PUFA-specific.[22]

^bEach PUFA-specific weighted-genetic score (wGS) represents a genetically-predicted level of PUFAs, which represent an increase in total percent of plasma fatty acids. Weights used to create the wGS were obtained from previous genome-wide association studies (GWAS).[20,21]

^cSNPs used in each instrument are independent with linkage disequilibrium (LD; as measured using the correlation coefficient, r²) less than 0.1.