rs11644943 — FTO FTO Mid-Gene Intron Variant

FTO rs11644943 — An Independent Obesity Signal Outside the Primary Intron-1 Cluster

The FTO gene — officially the fat mass and obesity-associated gene — contains one of the most replicated loci in obesity genetics. Most research has focused on a cluster of intron-1 variants¹¹ intron-1 variants
The first non-coding interval of FTO, approximately 53,738,000–53,800,000 bp on chromosome 16 (GRCh38), contains the best-studied GWAS hits for obesity including rs9939609 and the causal variant rs1421085 led by rs9939609 and the mechanistic variant rs1421085. But the FTO gene spans over 400 kilobases across chromosome 16, harboring multiple intronic regions, and rs11644943 sits at a distinct chromosomal position²² distinct chromosomal position
chr16:53,961,672 (GRCh38) — approximately 200 kilobases downstream of the primary intron-1 obesity cluster, in a separate linkage disequilibrium block from the well-characterized FTO obesity haplotype.

The Mechanism

rs11644943 is an intronic FTO variant. Like all FTO intronic variants, it does not alter the amino acid sequence of the FTO protein — instead, it sits within a non-coding regulatory region where it may influence local chromatin accessibility, splicing efficiency, or transcriptional output of neighboring exons. The FTO protein itself functions as an N6-methyladenosine (m6A) RNA demethylase³³ N6-methyladenosine (m6A) RNA demethylase
m6A is the most abundant chemical modification on messenger RNA. FTO erases it, altering mRNA stability and translation of target genes including those involved in appetite regulation and adipocyte differentiation. Elevated FTO expression raises ghrelin mRNA stability (increasing hunger drive) and promotes white adipocyte differentiation over thermogenic beige adipocytes (reducing resting energy expenditure). The T allele at rs11644943 may act through a similar upregulatory mechanism on FTO transcript levels in relevant tissues, though the specific regulatory element disrupted by this variant has not been characterized.

Critically, the rs11644943 T allele and nearby rs7206790 are not in linkage disequilibrium with previously reported obesity-associated FTO variants⁴⁴ the rs11644943 T allele and nearby rs7206790 are not in linkage disequilibrium with previously reported obesity-associated FTO variants
Xu et al. 2014 (PMID:25251416) explicitly confirmed that rs11644943 and rs7206790 are independent of rs9939609 and other previously catalogued FTO GWAS hits in the Chinese school-age population studied. This makes rs11644943 a potentially independent FTO obesity signal — tagging genetic variation in a different part of the gene rather than serving as a proxy for the primary intron-1 cluster.

The Evidence

Published evidence for rs11644943 is limited. The primary study is a case-control analysis in Chinese school-age children⁵⁵ case-control analysis in Chinese school-age children
Xu et al. Rs7206790 and rs11644943 in FTO gene are associated with risk of obesity in Chinese school-age population. PLoS One 2014. PMID:25251416 (500 obese cases, 500 matched controls). The investigators identified the A allele as protective: carriers of the AA genotype had a substantially lower risk of obesity compared to T-allele carriers (adjusted OR 0.16, 95% CI 0.04–0.72). The association survived adjustment for age, sex, and residential location. When combined with rs9939609 in a three-SNP genetic risk score model, dose-response relationships with obesity were observed, though rs11644943's contribution was confirmed as independent of the primary FTO locus.

Direct evidence for rs11644943 outside this single study is not yet available in the peer-reviewed literature, and the variant is not catalogued in ClinVar or the GWAS Catalog. The evidence level is therefore emerging — the association requires replication in larger and ethnically diverse cohorts before it can be considered a confirmed independent FTO signal. For context, the broader FTO locus has strong, replicated evidence for influencing obesity risk across populations⁶⁶ strong, replicated evidence for influencing obesity risk across populations
Frayling et al. Science 2007. PMID:17434869, with the primary intron-1 signal explaining an additive ~3 kg difference in body weight per risk allele in Europeans.

Practical Actions

Because rs11644943 is an FTO intronic variant, the genotype-specific advice derives from what is known about the FTO pathway. Physical activity consistently attenuates FTO-related obesity risk: a meta-analysis of 218,166 adults⁷⁷ meta-analysis of 218,166 adults
Kilpeläinen et al. 2011. PMID:22069379 found that physically active individuals showed a 27% lower FTO allele-associated obesity effect than sedentary individuals — one of the largest known gene-environment interactions in common disease genetics. Dietary protein composition also matters: higher-protein meals improve satiety signaling in FTO risk allele carriers by compensating for impaired gut hormone (GLP-1, PYY) responses. These effects have been demonstrated across FTO intron variants generally, though not yet specifically for rs11644943.

Interactions

rs11644943 is not in LD with the primary FTO intron-1 obesity cluster (rs9939609, rs1421085, rs8050136), making it a potentially additive second FTO signal. Users who carry both the T allele at rs11644943 AND the A risk allele at rs9939609 may carry compounded FTO pathway burden through independent intronic regulatory mechanisms. The adjacent variant rs7206790 (chr16:53,763,996) was studied alongside rs11644943 in the Chinese school-age cohort but appears to be in a different intron and LD block; the two variants together may index distinct regulatory regions across the FTO gene body.