rs10150332 — NRXN3

The Reward Circuit's Grip on Your Appetite

NRXN3 (Neurexin-3) is not a metabolic gene. It does not regulate insulin, store fat, or burn energy. It is a synaptic cell-adhesion molecule — one of a family of proteins that build and stabilize connections between neurons in the brain's reward and feeding circuits. Yet it was pulled out of genome-wide association studies as a genuine obesity risk locus, pointing to a fundamental truth: in many people, excess weight is a neurological problem before it is a metabolic one.

The Mechanism

Neurexins act as molecular bridges across synapses, binding neuroligins¹¹ neuroligins
Postsynaptic proteins that pair with neurexins to specify synapse type — excitatory (glutamatergic) or inhibitory (GABAergic) and dystroglycans²² dystroglycans
Extracellular matrix receptors at the synapse that stabilize the synaptic cleft on the postsynaptic side. Neurexin-3 specifically controls AMPA receptor³³ AMPA receptor
The ionotropic glutamate receptor responsible for fast excitatory neurotransmission; its strength determines how powerfully one neuron activates another strength at glutamatergic synapses, meaning it regulates how intensely reward signals propagate through circuits.

NRXN3 is expressed heavily in glutamatergic projections from the prefrontal cortex⁴⁴ prefrontal cortex
The brain region governing impulse control, decision-making, and behavioral inhibition to the nucleus accumbens⁵⁵ nucleus accumbens
The brain's primary reward hub — the target of dopamine released during pleasurable experiences including food, sex, and addictive substances and in GABAergic neurons within the striatum. These are precisely the circuits that determine whether a reward signal (the smell of food, the taste of sugar) generates a "stop — satisfied" response or a "keep going — I need more" response. Variants that alter NRXN3 expression shift this balance, reducing the brake on appetitive drive.

A striking 2024 animal study found that selectively deleting NRXN3 in CaMKIIα-expressing neurons⁶⁶ CaMKIIα-expressing neurons
Neurons expressing Calcium/calmodulin-dependent protein kinase II alpha, a marker of excitatory projection neurons in the PVN of the paraventricular nucleus (PVN) of the hypothalamus⁷⁷ paraventricular nucleus (PVN) of the hypothalamus
A hypothalamic region integrating autonomic and endocrine signals to regulate energy balance, stress, and circadian rhythms caused substantially greater body fat accumulation⁸⁸ substantially greater body fat accumulation
Mu et al. Neurexin-3 in the paraventricular nucleus of the hypothalamus regulates body weight and glucose homeostasis independently of food intake. Molecular Brain, 2024 and impaired glucose tolerance — remarkably, without changing food intake at all. This shows that NRXN3 in the hypothalamus governs energy partitioning (how calories are stored versus burned), not merely appetite. Reducing NRXN3 function biases metabolism toward fat storage and glucose intolerance through autonomic and neuroendocrine pathways independent of conscious hunger.

The Evidence

rs10150332 lies within an intron of NRXN3 on chromosome 14q31. It was first identified in a CHARGE consortium GWAS⁹⁹ CHARGE consortium GWAS
Heard-Costa et al. NRXN3 is a novel locus for waist circumference. PLoS Genetics, 2009 of 31,373 individuals as a novel waist circumference locus. The G allele of the tag SNP rs10146997 (in complete linkage disequilibrium with rs10150332) was associated with 0.65 cm greater waist circumference per allele (combined p = 5.3×10⁻⁸, n = 70,014) and an obesity odds ratio of 1.13 (95% CI 1.07–1.19).

The Speliotes 2010 GIANT consortium meta-analysis¹⁰¹⁰ GIANT consortium meta-analysis
Speliotes et al. Association analyses of 249,796 individuals reveal 18 new loci associated with body mass index. Nature Genetics, 2010 of 249,796 individuals confirmed rs10150332 directly in the BMI analysis, with the C allele associated with β = 0.13 kg/m² higher BMI (p = 3×10⁻¹¹). A 2024 electronic health record PheWAS in a diverse population found even stronger signals: the C allele associated with obesity (β = 0.052, p = 2×10⁻²²) and overweight (β = 0.049, p = 7×10⁻²¹).

The NRXN3 locus also shows strong association with obstructive sleep apnea¹¹¹¹ obstructive sleep apnea
A sleep disorder in which upper airway obstruction causes repeated breathing interruptions — strongly linked to central obesity (OR 1.031, p = 1×10⁻⁸), consistent with the downstream effects of abdominal fat accumulation that the C allele promotes.

One of the most clinically important findings is the addiction-obesity overlap¹²¹² addiction-obesity overlap
Hishimoto et al. Neurexin 3 polymorphisms are associated with alcohol dependence and altered expression of specific isoforms. Human Molecular Genetics, 2007: NRXN3 variants in the same gene region were independently linked to alcohol dependence (splice-site SNP rs8019381, OR 2.46, p = 0.0007). The broader NRXN3 haplotypes that alter expression of specific transmembrane isoforms predispose to vulnerability to multiple addictive substances. This makes rs10150332 one of a handful of genetic loci where obesity risk and substance dependence risk converge through shared reward circuitry.

The population frequency of the C allele shows extreme stratification: ~21% in Europeans and ~40% in Africans, but essentially absent in East Asian populations (<1%). This near-fixation of the T allele in East Asians is one of the most dramatic frequency differences among all known obesity loci.

Practical Implications

The key insight from the NRXN3 biology is that the drive behind overeating in C allele carriers operates through reward and impulse- control circuits — the same circuitry that underlies compulsive behavior in addiction. Standard appetite management strategies that work for hypothalamic hunger signals (protein satiety, calorie restriction) may be less effective in isolation. Strategies that specifically target reward-driven eating — eliminating highly palatable trigger foods, restructuring the food environment, and building alternative reward pathways — are more aligned with the genetic mechanism.

The 2024 hypothalamic finding — that Nrxn3 loss causes fat accumulation independently of food intake — also points to energy expenditure as a key target. If the PVN's autonomic output is less effective at directing calories toward thermogenesis, building non-exercise thermogenesis and cold exposure habits may help counter this deficit.

Interactions

The most clinically relevant interaction is with DRD2 rs1800497 (Taq1A) in the brain-mental-health category. Both NRXN3 and DRD2 act in the mesolimbic reward circuit: NRXN3 governs synaptic connectivity of reward circuits while DRD2 governs dopamine receptor density within them. Carriers of risk alleles at both loci — weaker reward-circuit synaptic architecture (NRXN3 C) plus lower dopamine receptor density (DRD2 A allele) — may experience markedly heightened vulnerability to reward-driven overeating and food addiction-like behavior. This combination warrants targeted food environment restructuring.

NRXN3 acts independently of FTO (rs9939609) and MC4R (rs17782313), which operate through hypothalamic appetite and melanocortin pathways rather than reward circuitry. Carriers of risk alleles at all three loci face additive genetic load for obesity through distinct mechanisms — hypothalamic leptin insensitivity (FTO), melanocortin signaling deficit (MC4R), and reward-circuit dysfunction (NRXN3) — each warranting its own management approach.