FABP1

FABP1 rs2197076 — An Intronic Marker in the Liver Fatty Acid Transport Gene

FABP1 (Fatty Acid Binding Protein 1), also called L-FABP or liver FABP, is the
most abundant cytosolic protein in human hepatocytes. It binds long-chain fatty
acids, bile acids, and other hydrophobic ligands and shuttles them from the plasma
membrane to the endoplasmic reticulum and mitochondria for esterification and
oxidation| FABP1 constitutes roughly 3-5% of total cytosolic protein in the adult
human liver; its extraordinary abundance reflects the hepatocyte's central role in
whole-body lipid homeostasis. By modulating the intracellular
concentration of free fatty acids, FABP1 directly influences hepatic triglyceride
synthesis, VLDL secretion, and fat oxidation.

rs2197076 is a G>A intronic variant in FABP1 (GRCh38: chr2:88,123,239;
NM_001443.3:c.334-135C>T in coding-strand notation — the gene sits on the minus
strand, so the plus-strand reference is G and the alternate is A). The variant does
not alter the FABP1 protein sequence; its clinical relevance lies in its association
with diabetes and metabolic risk phenotypes, and in its position within the same
haplotype block as the
T94A missense variant (rs2241883) | rs2241883 is a coding variant in FABP1 that
substitutes alanine for threonine at position 94 of the protein; this structural
change reduces the protein's fatty acid binding affinity and has been independently
linked to elevated triglycerides, LDL, and NAFLD risk.

The Mechanism

As an intronic variant, rs2197076 does not directly alter FABP1 protein function.
Its biological significance is likely one of two types: it may influence the
transcriptional regulation of FABP1 — reducing hepatic FABP1 expression so that
fewer binding sites are available for incoming fatty acids — or it may serve as a
tag SNP | A tag SNP is in linkage disequilibrium with one or more functional
variants in the same haplotype block; the tag SNP itself may be functionally
neutral, but its presence reliably predicts the presence of the functional allele
elsewhere on the chromosome marking
the T94A haplotype.

The liver FABP1 protein binds two fatty acid molecules simultaneously — a unique
feature among the FABP family — enabling high-flux lipid transport in hepatocytes
that process a continuous dietary fat load. When FABP1 is reduced or its binding
affinity is impaired, free long-chain fatty acids accumulate in the cytosol, activate
nuclear receptors differently, and may increase hepatic lipid deposition, triglyceride
synthesis, and insulin resistance signaling. The A allele of rs2197076 is the minor
allele in African and European populations (~9–18%) but approaches or exceeds 50%
in East and South Asian populations, making it a particularly relevant variant for
those ancestries.

The Evidence

The primary evidence for rs2197076 comes from a Spanish population study by Mansego
et al. | Mansego ML et al. Common variants of the liver fatty acid binding protein gene
influence the risk of type 2 diabetes and insulin resistance in Spanish population.
PLoS One 2012 that examined 1,217
participants in an original cohort and replicated findings in 805 Segovia subjects.
rs2197076 was the only single SNP in FABP1 to reach strong association with type 2
diabetes risk in both cohorts, and FABP1 haplotypes containing this variant also
associated with HOMA-IR (a direct index of insulin resistance). No FABP2, FABP3, or
FABP4 variants showed similar associations in the same study.

Two studies in polycystic ovary syndrome provide convergent evidence. Xue et al. 2016
| Xue H et al. Association of SNPs rs2197076 and rs2241883 of FABP1 gene with PCOS.
J Assist Reprod Genet 2016 genotyped both
rs2197076 and the T94A coding variant in 221 Chinese PCOS women and 198 controls,
finding P<0.001 for allele frequency differences; rs2197076 associated more strongly
with core PCOS features than rs2241883, suggesting an independent regulatory
contribution. Rashid et al. 2017 | Rashid N et al. Association of IL-1β, IL-1Ra and
FABP1 gene polymorphisms with metabolic features of PCOS. Inflamm Res 2017 confirmed that the A allele specifically
correlated with dyslipidemia and cardiovascular risk biomarkers in PCOS patients.

Mechanistic context for the haplotype is provided by studies of the T94A coding variant
(rs2241883). Schroeder et al. 2016 | Schroeder F et al. Fatty acid binding protein-1
and the human FABP1 T94A variant: roles in the endocannabinoid system and dyslipidemias.
Lipids 2016 reviewed evidence that T94A
expression in males increases hepatic triglycerides and cholesteryl esters through
disrupted endocannabinoid enzyme transcription. The T94A variant also shows sex-dependent
effects — female carriers exhibit compensatory metabolic adjustments that limit lipid
accumulation relative to males. Whether rs2197076 tracks these effects independently or
entirely through LD with rs2241883 is not yet resolved, but the combined evidence positions
the FABP1 locus as a genuine metabolic risk factor, particularly for individuals of
East and South Asian ancestry where the A allele is common.

The overall evidence supports a moderate rating: findings are replicated across three
independent studies but remain confined to relatively small cohorts and specific
populations, with no large GWAS signal or clinical-grade guideline.

Practical Actions

For A-allele carriers, the key leverage points are dietary fat quality, hepatic biomarker
monitoring, and awareness of insulin resistance risk. Since FABP1 handles the intracellular
distribution of fatty acids in the liver, the composition of dietary fat matters: saturated
and trans fats promote hepatic triglyceride accumulation, while long-chain omega-3 fatty
acids (EPA/DHA) activate hepatic PPARα and reduce triglyceride synthesis. Monitoring fasting
triglycerides and glucose provides an early window into whether FABP1 haplotype variation is
expressing itself metabolically.

Interactions

rs2197076 is physically close to and likely in partial linkage disequilibrium with
rs2241883 (T94A), the missense variant in FABP1 exon 3. Both SNPs have been studied
together in PCOS cohorts. The T94A missense has independent literature supporting its
effect on lipid metabolism and NAFLD. If you carry risk alleles at both rs2197076 and
rs2241883, the combined FABP1 haplotype may represent greater impairment of hepatic
fatty acid handling than either SNP alone, though no published study has formally
quantified a compound effect.

The FABP1 locus also intersects with dietary fat intake: the variant's metabolic effects
are more pronounced in high-fat dietary contexts where hepatic FABP1 is under greatest
demand. Individuals with FABP family risk variants (including FABP2 Ala54Thr, rs1799883)
may carry compound metabolic fatty acid handling burden across intestinal absorption and
hepatic transport.