rs11644943 — FTO FTO Mid-Gene Intron Variant

An intronic FTO variant outside the well-known intron-1 obesity cluster; the T allele (GRCh38 reference, ~77% globally) is associated with increased obesity risk in Asian populations, while the protective A allele reduces obesity susceptibility. Not in linkage disequilibrium with the primary FTO obesity signals (rs9939609, rs1421085).

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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.

Genotype Interpretations

What each possible genotype means for this variant.

AA Protective Genotype Normal

Protective genotype — lowest obesity susceptibility at this FTO locus

You carry two copies of the protective A allele at rs11644943. This is the rarest genotype globally (approximately 5% of people), but it confers the lowest obesity risk at this FTO locus. In the only published study of this variant, AA carriers had an adjusted odds ratio of 0.16 for obesity compared to T-allele carriers — indicating dramatically lower risk. Your T allele count is zero, meaning you do not carry the risk signal at this specific FTO mid-gene region.

The A allele frequency is approximately 23% globally (gnomAD v4), making AA homozygotes uncommon. South Asian and Latino populations have modestly higher A allele frequencies (~27–28%) than East Asians (~15%) or Africans (~18%).

AT One Risk Allele Intermediate

One copy of the FTO risk allele — modestly elevated obesity susceptibility

rs11644943 tags a region of FTO approximately 200 kilobases downstream of the well-studied intron-1 obesity cluster (rs9939609, rs1421085). The protective A allele likely influences regulatory elements that modulate FTO transcript levels or splicing in the mid-gene region. As a heterozygote, you carry one copy of each allele, with an expected intermediate effect compared to AA and TT homozygotes. The broader FTO locus biology — where physical activity attenuates genetic risk by up to 27% (Kilpeläinen et al. 2011, n=218,166) — is likely to apply to carriers of this variant as well, given its functional context within FTO.

TT Elevated Risk High Risk

Two copies of the FTO risk allele — highest obesity susceptibility at this locus

TT homozygotes at rs11644943 carry the full allele dosage at this locus, which was identified as the obesity risk genotype in a 1,000-participant Chinese school- age study. The variant sits approximately 200 kilobases downstream of the primary FTO intron-1 obesity cluster and is not in linkage disequilibrium with rs9939609 or rs1421085, suggesting it may tag a distinct regulatory element in the FTO gene body. The mechanism likely involves altered FTO transcriptional regulation — similar to how intron-1 variants affect FTO mRNA levels, which then modulates ghrelin mRNA stability (appetite) and adipocyte differentiation (fat storage vs. thermogenesis).

The key actionable finding across the FTO locus is the gene-environment interaction with physical activity: in a meta-analysis of 218,166 adults (Kilpeläinen et al. 2011), active individuals showed 27% lower FTO allele-associated obesity effect than sedentary individuals. This interaction makes FTO the most exercise-modifiable common obesity locus identified to date.