rs1805097 — IRS2 Gly1057Asp

Missense IRS2 variant where Asp/Asp homozygotes are twice as likely to reach extreme old age — mediates longevity via reduced insulin/IGF-1 signaling, but its protective effect reverses sharply with obesity

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IRS2 Gly1057Asp — The Longevity Variant That Requires You to Stay Lean

The insulin/IGF-1 signaling (IIS) pathway is the most conserved longevity pathway across all studied species. Reduce it in yeast, worms, flies, or mice, and lifespan extends. IRS2 — insulin receptor substrate 2 — is the critical intracellular docking protein that receives the IGF-1 receptor's signal and amplifies it through the PI3K-AKT-mTOR cascade. In mice, complete IRS2 knockout extends median lifespan by up to 20%11 In mice, complete IRS2 knockout extends median lifespan by up to 20%
White MF. IRS2 integrates insulin/IGF1 signalling with metabolism, neurodegeneration and longevity. Diabetes Obes Metab. 2014. rs1805097 creates a glycine-to-aspartic acid substitution at position 1057 of the IRS2 protein — a structural shift in the C-terminal domain that alters the protein's signaling efficiency. Homozygous carriers of the Asp variant are approximately twice as likely to reach extreme old age.

The Mechanism

IRS2 sits just downstream of both the insulin receptor and the IGF-1 receptor (IGF1R). When either receptor is activated, IRS2 becomes tyrosine-phosphorylated and recruits PI3-kinase, triggering a cascade culminating in AKT and mTOR activation. This drives growth, protein synthesis, and cellular proliferation — metabolically costly processes that appear to accelerate biological aging22 accelerate biological aging
White MF. 2014.

The Gly1057Asp substitution falls within the C-terminal serine phosphorylation domain of IRS2. Position 1057 lies near a cluster of regulatory serine residues that govern IRS2 stability and interaction with downstream signaling partners. The aspartic acid substitution (negatively charged, versus neutral glycine) may subtly alter the protein's folding and its interaction with 14-3-3 proteins and E3 ubiquitin ligases — mechanisms that control IRS2 protein levels. The result appears to be modestly attenuated IIS flux, which the longevity literature uniformly associates with extended healthspan. Importantly, the fasting C-peptide levels of Asp allele carriers are inversely correlated with allele dosage in lean individuals, suggesting higher insulin sensitivity — a fundamentally different mechanism than the lifespan extension observed in IRS2 knockout mice, and one that is highly context-dependent.

The Evidence

The primary human longevity study comes from Barbieri et al. 201033 Barbieri et al. 2010
Barbieri M et al. The IRS2 Gly1057Asp variant is associated with human longevity. J Gerontol A Biol Sci Med Sci. 2010. Among 677 Italian participants (ages 16-104), homozygous Asp/Asp individuals were significantly overrepresented among long-lived subjects (>85 years old) compared to controls (16.7% vs 12.0%, p = .04). When focused on extreme old age (ages 96-104), Asp/Asp individuals had a 2.03-fold increased probability of reaching that age (95% CI 1.39-2.99, p = .0003). After adjusting for anthropometric and metabolic covariates, the overall longevity odds ratio was 2.07 (95% CI 1.38-3.12, p = .001), confirming the association is independent of body weight and metabolic status.

A gene-combination study Barbieri et al. 201244 Barbieri et al. 2012
Barbieri M et al. A/Asp/Val allele combination of IGF1R, IRS2, and UCP2 genes is associated with better metabolic profile, preserved energy expenditure parameters, and low mortality rate in longevity. Age (Dordr). 2012 examined 722 Italian subjects and found that when the IRS2-Asp allele is combined with the IGF1R longevity A-allele (rs2229765) and the UCP2 Val allele (rs659366), the longevity association is dramatically amplified: OR 3.185 (95% CI 1.63-6.19, p = .0006). The combination also correlated with lower HOMA-IR (diff −0.532, p = 0.003), higher resting metabolic rate (diff ~102 kcal/day, p = 0.038), and decreased all-cause mortality (HR 0.72) over six years of follow-up.

The critical contextual finding comes from Mammarella et al. 200055 Mammarella et al. 2000
Mammarella S et al. Interaction between the G1057D variant of IRS-2 and overweight in the pathogenesis of type 2 diabetes. Hum Mol Genet. 2000. In Italian subjects without overweight, the Asp allele dose-dependently protected against type 2 diabetes (DD genotype OR 0.18, 95% CI 0.04-0.68; p for trend = .0012). But in overweight subjects, the same genotype reversed to dramatically increase diabetes risk (DD OR 5.74, 95% CI 1.11-29.78; p for trend = .0047). This genotype-environment interaction is one of the most dramatic in the IIS literature and fundamentally shapes how to interpret your results.

Practical Implications

The Asp variant's longevity benefit appears to operate through subtly reduced IIS flux in the lean state, where higher insulin sensitivity reduces the chronic mTOR activation that accelerates cellular aging. Maintaining normal body weight is therefore the primary intervention for Asp allele carriers — not because weight management is generic health advice, but because this specific variant's protective effect mechanistically depends on metabolic context. Overweight Asp/Asp carriers face a compound risk: their attenuated IRS2 signaling, combined with the chronic hyperinsulinemia of obesity, creates insulin resistance rather than insulin sensitivity.

Monitoring fasting insulin and HOMA-IR (calculated from fasting glucose and insulin) provides a direct readout of whether your IRS2 variant is functioning in its protective mode or reverting to its insulin-resistant mode. Asp/Asp individuals in their 60s and beyond should also monitor for signs of cardiac metabolic risk, as one study found higher epicardial fat thickness in elderly Asp carriers, independent of body weight.

Interactions

The strongest documented interaction is the IGF1R-IRS2-UCP2 triple combination. IGF1R rs2229765 sits directly upstream of IRS2 in the signaling cascade; when both genes carry their longevity variants, the combined attenuation of IIS flux is amplified beyond either variant alone. UCP2 rs659366 (Val allele) modulates mitochondrial uncoupling downstream of the pathway, adding a third layer of IIS attenuation. The OR of 3.185 for the triple combination versus ~2.0 for IRS2 alone quantifies this synergy.

The IIS pathway also intersects with neurodegeneration: reduced IRS2 signaling protects against tau hyperphosphorylation and amyloid accumulation in animal models of Alzheimer's disease. Human brains with Alzheimer's disease show specifically reduced IRS2 levels in affected neurons. Whether the Gly1057Asp variant modifies dementia risk in humans has not been directly tested.

Genotype Interpretations

What each possible genotype means for this variant.

CC Standard IIS Signaling Normal

Standard IRS2 signaling without the longevity-associated Asp variant

You carry two copies of the common Gly allele (C on the plus strand), the most prevalent genotype in European and African populations. About 49% of the global population shares this genotype. Your IRS2 protein functions at full standard capacity, efficiently relaying insulin and IGF-1 receptor signals through the PI3K-AKT-mTOR cascade. This is the baseline configuration without the IIS-attenuating effect of the Asp variant.

TT Dual Longevity Alleles Beneficial

Two copies of the Asp longevity variant — doubled probability of extreme old age, contingent on lean body composition

The Asp/Asp genotype represents the most attenuated IIS signaling of the three possible genotypes. In lean individuals, this manifests as enhanced insulin sensitivity (lower fasting C-peptide per unit of insulin signal, indicating efficient glucose handling with lower compensatory beta-cell output). This is mechanistically analogous to — though far smaller in magnitude than — the lifespan-extending effect of partial IRS2 reduction in mice.

The gene combination study (Barbieri et al. 2012) found that when Asp/Asp is combined with the IGF1R longevity allele and UCP2 Val allele, the longevity probability is amplified to OR 3.185. This amplification suggests the longevity benefit scales with the number of IIS-attenuating variants a person carries.

There is a nuanced aging paradox: one study of elderly subjects found that Asp carriers had higher HOMA-IR than non-carriers in old age (HOMA-IR 3.40 vs 2.21, p<0.001), along with increased epicardial fat thickness. This does not contradict the longevity finding but suggests that surviving to old age with this genotype does not prevent some metabolic changes — or that elderly Asp carriers who are overweight show the reverse-effect more prominently. Tracking metabolic markers across the lifespan remains essential.

CT One Longevity Allele Intermediate

One copy of the Asp longevity variant — partial IIS attenuation with weight-dependent effects

The Italian longevity study (Barbieri et al. 2010) pooled heterozygotes with homozygous Asp carriers in the "Asp allele" group for analysis, making it difficult to quantify the exact CT advantage versus TT. The diabetes interaction data (Mammarella et al. 2000) shows that GD heterozygotes have intermediate effects in both directions: protective in lean individuals (OR 0.46, 95% CI 0.25-0.86) and modestly risk-increasing in overweight individuals (OR 2.50, 95% CI 1.11-5.65), compared to the more extreme effects seen in homozygotes. Monitoring body composition and fasting insulin is particularly informative for CT carriers to determine which mode their IRS2 signaling is operating in.