NTRK2 rs2229764: Genetic Variation and Metabolic Research
The genetic variant rs2229764 is a missense single-nucleotide polymorphism located within the NTRK2 gene on chromosome 9. The NTRK2 gene encodes tropomyosin receptor kinase B (TrkB), a key receptor involved in neurodevelopment and central energy regulation. While severe loss-of-function mutations in NTRK2 cause rare neurodevelopmental and hyperphagic obesity syndromes, rs2229764 has been investigated across population cohorts for potential modest associations with body mass index, though clinical evidence remains limited.
What each genotype means
| Genotype | What the research suggests | Reading |
|---|---|---|
| CC | This genotype represents two copies of the common ancestral C allele at the rs2229764 locus. Individuals with this genotype produce standard TrkB receptors and display baseline population-level metabolic parameters for this specific site. It is not associated with altered energy balance or elevated genetic risk for early-onset obesity. | Informational |
| CT | Carriers of the heterozygous CT genotype possess one reference allele and one alternative missense allele. Cohort studies show this genotype is found in a small percentage of the general population and does not cause monogenic obesity. Available research indicates limited and conflicting evidence regarding any subtle effect on average body mass index. | Informational |
| TT | The homozygous TT genotype indicates two copies of the alternative missense allele at rs2229764. Because the minor allele frequency is low, this homozygous state is rarely observed in population databases such as gnomAD. Current scientific evidence is insufficient to establish a definitive clinical consequence or deterministic disease risk. | Informational |
Genomic Location and Variant Characteristics
The single-nucleotide polymorphism rs2229764 is located within the human NTRK2 gene, mapped to the short arm of chromosome 9 (9q21.33). As cataloged in the National Center for Biotechnology Information's dbSNP database, this variant represents a single base-pair change that causes a missense amino acid substitution in the resulting protein. The NTRK2 transcript produces Tropomyosin receptor kinase B (TrkB), a transmembrane protein that traverses neural membranes. Missense variants alter the coding sequence of an exon, meaning that ribosomes incorporate an alternative amino acid at that position during protein synthesis. Researchers study missense changes to evaluate whether they alter the receptor's tertiary structure, surface expression, ligand-binding capacity, or intracellular kinase phosphorylation cascades.
Biological Role of the NTRK2 Receptor
The NTRK2 gene encodes TrkB, the high-affinity catalytic receptor for brain-derived neurotrophic factor (BDNF) and neurotrophin-4. When BDNF binds to TrkB, the receptor undergoes dimerization and autophosphorylation, initiating intracellular signaling cascades such as the MAPK/ERK, PI3K/Akt, and PLC-gamma pathways. In the central nervous system, particularly within the hypothalamus, the BDNF-TrkB signaling axis operates downstream of the leptin-melanocortin circuit to suppress appetite, regulate satiety, and modulate basal metabolic energy expenditure. Monogenic disruption or loss-of-function variants in NTRK2 can severely disrupt satiety signaling, resulting in rare developmental syndromes characterized by hyperphagia and severe early-onset obesity.
Population Associations and Evidence Strength
Because rare monogenic mutations in NTRK2 cause severe human obesity syndromes, researchers have examined low-frequency coding variants such as rs2229764 in broader cohorts. Multiple genetic association and fine-mapping studies have evaluated whether rs2229764 exerts measurable effects on adult body mass index or pediatric adiposity. However, the evidence supporting a clear phenotypic effect for rs2229764 is currently classified as limited. While some candidate-gene studies suggested possible modest shifts in metabolic traits, broad genome-wide association studies (GWAS) and population-scale exome sequencing efforts, including UK Biobank evaluations, indicate that rs2229764 does not behave as a high-penetrance monogenic driver. Instead, any influence on body mass index appears small, polygenic, or contingent on broader genetic and environmental contexts.
Clinical Interpretation and Limitations
Genomic knowledge surrounding rs2229764 has significant clinical limitations and should not be used as a standalone diagnostic tool. Standard clinical testing distinguishes highly penetrant, pathogenic loss-of-function mutations from common and low-frequency missense polymorphisms. Having an alternative allele at rs2229764 does not diagnose obesity, hyperphagia, or any neurodevelopmental condition. Body weight regulation is an intrinsically complex polygenic trait shaped by hundreds of small-effect genetic variants interacting with nutrition, physical activity, sleep, and socio-environmental factors. Readers should not interpret genetic commercial test results for this variant as determinative, and no personal medical decisions or weight-management interventions should be made without guidance from qualified healthcare professionals.
How common is this variant?
According to the Genome Aggregation Database (gnomAD), the minor allele frequency of rs2229764 ranges between approximately 0.01 and 0.03 (1% to 3%) across European ancestries. Homozygous carriers of the minor allele are relatively rare in global reference populations.
Frequently asked questions
What is the NTRK2 rs2229764 variant?
rs2229764 is a missense single-nucleotide polymorphism in the human NTRK2 gene. It results in an amino acid change within the TrkB receptor, a protein essential for brain-derived neurotrophic factor signaling.
Does having the rs2229764 variant cause severe obesity?
No, rs2229764 does not cause monogenic obesity. While severe loss-of-function disruptions in NTRK2 can cause syndromic obesity, rs2229764 is a low-frequency variant with limited and inconclusive evidence regarding minor variations in body mass index.
How common is rs2229764 in the general population?
The minor allele is present at an estimated frequency of 1% to 3% in populations of European ancestry, meaning the vast majority of individuals carry the common homozygous genotype.
Can I use rs2229764 to choose a diet or medical treatment?
No, this genetic variant cannot be used to guide dietary strategies, pharmaceutical choices, or weight loss plans. Individuals seeking to address weight or metabolic health should consult a physician or registered dietitian.
Sources & further reading
Educational information only, last refreshed 9/7/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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