rs12470652 — LHCGR Asn291Ser (N291S)

Missense variant in the LH/hCG receptor producing a gain-of-function increase in receptor sensitivity, influencing ovarian stimulation response, IVF outcomes, and gonadotropin-dependent signaling

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LHCGR Asn291Ser — Increased LH Receptor Sensitivity and Its Consequences for IVF Response

The luteinizing hormone/choriogonadotropin receptor (LHCGR) is the gateway through which LH and hCG direct ovulation, corpus luteum function, and ovarian steroidogenesis. The Asn291Ser variant — a single amino acid change at position 291 from asparagine (N) to serine (S) — lies in exon 10, encoding the extracellular ligand-binding domain. Unlike its neighboring variant at position 312 (rs2293275, also in LHCGR exon 10), this variant is rare in most populations: the C allele (Ser291) reaches about 5.6% in Europeans but is nearly absent in East Asian populations (0.01%). For the small fraction of women carrying this allele, the functional consequence is increased receptor sensitivity — a property with measurable implications for ovarian stimulation and reproductive outcomes.

The Mechanism

LHCGR is a G protein-coupled receptor11 G protein-coupled receptor
Receptors that activate intracellular signaling cascades via G proteins when bound by hormone ligands. LH binding activates Gs proteins, stimulating adenylyl cyclase to produce cAMP, which in turn drives follicular maturation, ovulation, and steroid synthesis in ovarian theca and granulosa cells.

Asparagine at position 291 (encoded by the T allele on the plus strand) is a candidate site for N-linked glycosylation — a sugar modification that affects protein folding, cell-surface trafficking, and receptor sensitivity. Serine (encoded by C) cannot accept N-linked glycosylation at this position. In vitro transfection studies22 In vitro transfection studies
Piersma et al. Polymorphic variations in exon 10 of the luteinizing hormone receptor. Mol Cell Endocrinol, 2007 revealed that the 291Ser variant (C allele) displays altered glycosylation status and increased receptor sensitivity relative to the wild-type 291Asn (T allele). This gain-of-function property means that cells expressing the Ser variant respond to lower concentrations of LH and achieve greater downstream cAMP signaling per unit of hormone.

The Evidence

IVF ovarian stimulation response. A 2023 prospective multicenter study of 94 normogonadotropic women undergoing IVF33 A 2023 prospective multicenter study of 94 normogonadotropic women undergoing IVF
Alviggi et al. Genes (Basel), 2023 genotyped eight gonadotropin receptor polymorphisms and measured ovarian stimulation outcomes. Women homozygous for the T allele (TT, Asn/Asn) retrieved fewer fertilized oocytes than heterozygous C/T carriers (p=0.035), and fewer mature oocytes (p=0.05). When the rs12470652 C allele was combined with specific FSHR variants (FSHR-29 rs1394205 G allele and FSHR rs6166 G allele), the FSH dose-to-oocyte ratio increased by 5.44-fold (95% CI: 3.18–7.71, p<0.001), signaling markedly worse ovarian response in this combined genotype group.

PCOS association. A 2022 case-control study of 743 women (421 PCOS, 322 controls) from Punjab, India44 A 2022 case-control study of 743 women (421 PCOS, 322 controls) from Punjab, India
Singh et al. BMC Endocrine Disorders, 2022 found the mutant C allele conferred a 2.3-fold risk toward PCOS progression. However, a 2025 meta-analysis55 a 2025 meta-analysis
Singh et al. Journal of Assisted Reproduction and Genetics, 2025 examining multiple LHCGR variants across multiple studies found rs12470652 did not show statistically significant association with PCOS in any genetic model overall, suggesting the single-study finding may be population-specific.

Male fertility. Simoni et al. 2008 (n=826 European men)66 Simoni et al. 2008 (n=826 European men)
Pharmacogenet Genomics, 2008 found that neither the N291S variant nor the insLQ variant showed differential distribution between men with maldescended testes, infertile men, and controls, indicating these functional variants do not strongly predispose to cryptorchidism or male infertility in European populations. An earlier 2002 study77 2002 study
Mongan et al. Eur J Endocrinol, 2002 found homozygosity for TT (N291) was modestly more frequent in undermasculinised males (p=0.05), with the combination of TT genotype and absence of the S312 allele yielding an OR of 3.28 (95% CI 1.33–8.08) for undermasculinisation — though this finding has not been replicated at scale.

The overall evidence picture is one of a variant with clear molecular function (increased receptor sensitivity) but modest and population-variable clinical associations. The IVF stimulation data is the most actionable finding, particularly for women combining rs12470652 carrier status with specific FSHR variants.

Practical Implications

The C allele is rare enough (global frequency ~5%) that most people carry two T alleles (wild-type). For the minority carrying one or two C alleles, the main clinically actionable context is IVF or other forms of ovarian stimulation. The increased receptor sensitivity suggests that C allele carriers may respond differently to exogenous LH during controlled ovarian stimulation — their receptors are more easily activated, which may alter optimal gonadotropin dosing.

For C allele carriers concerned about PCOS, the evidence is currently inconsistent across populations and should not be interpreted as a strong PCOS risk signal without corroborating clinical findings.

Interactions

rs2293275 (LHCGR N312S): The most relevant interaction is with the adjacent exon 10 variant at position 312. Both N291S and N312S affect glycosylation sites in the same extracellular domain, and both increase receptor sensitivity. Carriers of both functional variants (rs12470652 C allele + rs2293275 T allele) may have a cumulative alteration in receptor sensitivity that exceeds either variant alone. The functional literature treats these as independent glycosylation site changes with additive potential, though formal combined-effect clinical data is limited.

rs6166 (FSHR N680S): The Alviggi 2023 study specifically demonstrated that the interaction between rs12470652 C allele and FSHR variants (rs1394205 and rs6166) creates a distinct poor-ovarian-response phenotype with 5.44-fold higher FSH dose requirement. This makes FSHR genotyping highly relevant for rs12470652 C allele carriers undergoing IVF.

Genotype Interpretations

What each possible genotype means for this variant.

TT Standard LH Sensitivity Normal

Two copies of the Asn variant — standard LH receptor glycosylation, typical ovarian stimulation response

The TT genotype retains the asparagine residue at position 291, preserving the candidate N-linked glycosylation site. In vitro, this correlates with lower receptor sensitivity relative to the Ser variant. In the clinical IVF context, TT homozygotes showed numerically lower oocyte yields than TC carriers in one study (p=0.035), though this sample was small (n=94) and the finding should be interpreted cautiously.

For most reproductive contexts, TT genotype represents the reference state. Standard IVF protocols have been developed and optimized predominantly in TT populations given the rarity of the C allele.

CT Increased LH Sensitivity (Heterozygous) Intermediate

One copy of the Ser variant — mildly increased LH receptor sensitivity, monitor ovarian response during stimulation

The CT genotype produces a mixed receptor population. The Ser variant's increased sensitivity means even sub-physiological LH levels can activate downstream cAMP signaling, which may affect follicular development dynamics during controlled ovarian stimulation.

In the Alviggi 2023 study, CT carriers outperformed TT homozygotes in oocyte retrieval (p=0.035 for fertilized oocytes). When combined with specific FSHR variants, however, CT carriers fell into the highest FSH dose-to-oocyte ratio group (RR 5.44), suggesting the overall gonadotropin receptor background matters more than rs12470652 alone.

The Indian PCOS study reported elevated PCOS risk with the C allele (2.3-fold), though the 2025 meta-analysis did not replicate this finding overall.

CC Significantly Increased LH Sensitivity High

Two copies of the Ser variant — marked increase in LH receptor sensitivity, risk of altered ovarian stimulation response

The CC genotype is rare enough that published clinical cohorts have very limited data specific to Ser/Ser homozygotes; most studies group TC and CC as "C allele carriers" due to the scarcity of CC individuals. The in vitro characterization from Piersma et al. 2007 confirms that Ser291 confers increased receptor sensitivity, and homozygosity for this allele would be expected to amplify this effect relative to heterozygosity.

Practically, CC individuals undergoing IVF face the greatest need for genotype-informed protocol design. Standard stimulation protocols assume normal receptor kinetics; the heightened sensitivity of the CC receptor pool may result in an exaggerated response to standard gonadotropin doses, requiring careful monitoring for ovarian hyperstimulation. Conversely, if FSHR co-variants are unfavorable, the combined receptor background may still limit total oocyte yield.

Given the rarity of this genotype, any reproductive endocrinologist managing a CC carrier will be working with limited population-specific data and should consider specialist consultation or careful dose titration.