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Nutrigenetic Impact of PEMT Gene Polymorphism Rs7946 On

Choline Metabolism and Its Role in Personalised Nutrition

Dr. Shamya Reny

metabolism. Individuals carrying Aallele exhibit reduced PEMT activity, predisposing themto non-alcoholic fatty liver disease

(NAFLD), elevated homocysteine levels, and reproductive or cognitive risks under low choline diets. This impact is modulated

by sex hormones, particularly oestrogen, rendering postmenopausal women more susceptible. This review summarises recent

findings linking PEMT rs7946 variants with metabolic, hepatic, and psychological outcomes and explores gene diet interactions

that informs genotype based nutritional recommendations. It also suggests tailored choline intake strategies based on genotype.

We argue for the integration of PEMT screening in nutritional counselling, especially for vulnerable groups. Future nutrigenetics

research is necessary to refine these guidelines and assess long-term impacts.

Keywords -PEMT gene, rs7946, polymorphism, SNP, phosphatidylcholine choline, nutrigenetics, NAFLD, one carbon

metabolism.

I. Introduction

and disease susceptibility.

Studies have shown that individuals with A allele (methionine variant) may have reduced choline biosynthesis and increased risk

to non-alcoholic fatty liver disease (NAFLD), metabolic disorders and adverse pregnancy outcomes, especially under low choline

diets (Zhu et al., 2020; Tan et al., 2016). This gene-diet interaction is modulated by hormonal factors such as oestrogen which

upregulates PEMT making postmenopausal women or those with low oestrogen levels more vulnerable (Harrison et al., 2020).

Emerging data also suggest that rs7946 influences choline’s effects on lipid metabolism, anxiety, cognitive function, and cancer

risk (Myoidzk et al.,2021 ; He et al., 2024; Zhang et al., 2024). These findings highlight the need to incorporate PEMT genetic

profiling into dietary recommendations, especially for populations at higher metabolic risk.

This paper reviews the structure, function, and health implications of PEMT rs7946 polymorphism and proposes genotype-guided

choline intake recommendations based on findings from recent clinical and molecular studies to build a foundation for precision

health.

Highlight genotype specific choline intake recommendations and implications for precision nutrition strategies.

Identify gaps in current knowledge and propose future research directions.

Functional Role of PEMT Gene

Gene Structure and Expression –The PEMT gene is located in chromosome 17, specifically at the p11.2 band and consists of

multiple exons encoding the enzyme responsible for catalysing the conversion of phosphatidylethanolamine to

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phosphatidylcholine via methylation. This reaction occurs primarily in the liver and plays a compensatory role when dietary

choline intake is low (Ganz et al., 2017). Expression of PEMT is modulated by various factors, including hormonal levels and

methyl donor availability.

PEMT in phosphatidylcholine Biosynthesis- PEMT catalyses three methylation steps, using S-adenosylmethionine (SAM) as a

protectedfrom choline deficiency disorders, while postmenopausal women and men with PEMT variants are more vulnerable

(Harrison et al., 2020). Oestrogen deficient states also reduce endogenous choline synthesis, increasing dietary choline

dependence.

rs7946 Polymorphism and Health Implications

The diagram below illustrates how the rs7946 mutation in the PEMT gene inhibits endogenous phosphatidylcholine synthesis,

with impaired PEMT activity, reliance on dietary choline increases. The resulting choline deficiency may lead to conditions such

as NAFLD, elevated homocysteine levels, and cognitive deficits.

Choline Deficiency and One-Carbon Metabolism- The rs7946 polymorphism results in a valine tomethionine substitution,

which impairs PEMT enzymatic activity. Individuals with the A allele variation of gene require higher dietary choline to

protective role means that postmenopausal women with this genotype are disproportionately affected (Harrison et al., 2020).

Cardio metabolic and Cognitive Impacts – Altered PEMT function has been associated with increased cardio-metabolic risk

markers such as LDL cholesterol and insulin resistance (Zhu et al., 2020). Moreover, reduced choline biosynthesis affects brain

acetylcholine synthesis, influencing memory and cognitive flexibility. Another study Myoidzk et al. (2021) demonstrated higher

anxiety scores in A allele carriers with low dietary choline, underlying a genetic basis for choline responsive neurological traits.

Reproductive Health and Cancer Risk- PEMT activity also influences reproductive outcomes. Women with the A allele have

shown higher risk for pre-eclampsia, neural tube defects in offspring, and fertility when dietary choline is insufficient (Tan et al.,

2016).Another recent study by Zhang et al., (2024) have suggested a correlation between rs7946 and colorectal cancer

susceptibility,although mechanistic links require further investigation.

Nutrigenetics Insights and Implications for Precision Nutrition

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influence on endogenous phosphatidylcholine synthesis and methylation metabolism. This variant alters choline requirements,

lipid metabolism and susceptibility to several non-communicable diseases.

capacity for de novo phosphatidylcholine synthesis. Individuals with the genotype, especially under conditions of low dietary

genotype require greater choline intake, particularly during pregnancy or in postmenopausal life stages when hormonal support is

diminished.

individuals who require modified dietary choline levels or closer metabolic monitoring.

This approach supports the movement toward personalised health care, in which nutritional recommendations influenced by

genotype, sex, age, lifestyle and physiological status. The implementation of PEMT focused dietary planning holds potential for

reducing disease burden and improving outcomes in at risk populations.

Recent evidence indicate the influence of rs 7946 PEMT gene on individual dietary responses.Myoidzk et al.(2021) reported that

rs7946 variant, along with rs12325817,affects lipid profiles and liver markers particularly in over weight individuals, while the

effects of choline were dependent on genotype and weight status. These indicates the importance of tailored nutrition based on

both genetics and anthropometry.

In Chinese adults, those with the CC genotype had a 31% higher risk of digestive cancers when choline to betaine ratios were

low, this highlights choline’s role in one-carbon metabolism(He.Q et al., 2024).Similarly , Da Costa et al, (2017) found that

women with the A allele showed altered choline metabolism, even with sufficient intake particularly during pregnancy and

lactation.

precision nutrition.

The recognition of PEMT rs7946 polymorphism in shaping individual responses to dietary choline marks a critical advancement

in personalised nutrition. Carriers of the A allele have a reduced capacity for endogenous choline synthesis, necessitating higher

dietary intake,particularly during life stages or conditions of increased demand such as pregnancy, menopause or chronic liver

disease(Ganz et al., 2017 ; Tan et al., 2016).

Knowledge of an individual’s PEMT genotype can inform dietary recommendations, particularly regarding choline intake.

Current adequate intake levels for choline may be insufficient for individuals with impaired PEMT function. Dietary sources rich

in Choline such as eggs, meat and soybeans can help mitigate deficiency in genetically predisposed populations (Niculescu

,2022).Table 1 summarises the relationship between PEMT rs7946 genotypes, their impact on enzymatic activity and the

associated choline requirements and health risks.

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Current Choline intake recommendations (550 mg/day for men and 425 mg/day for women) may be insufficient for individuals

with PEMT variants, especially when estrogen levels are low. Emerging research proposes genotype-specific choline guidelines

to mitigate risks of NAFLD, neurocognitive decline, and cardio metabolic disturbances (Wu et al ., 2023; Zhu et al ., 2020).

From a public health standpoint, nutrigenetic screening could identify at risk populations and inform early dietary

more reliant on adequate dietary choline intake. Personalised recommendations based on sex, genotype, and physiological state

(e.g. Pregnancy, menopause) are warranted to mitigate metabolic risks such as hepatic steatosis and homocysteine accumulation.

Optimising Choline Intake According to sex and Genotype

Dietary choline requirements vary depending on PEMT genotype and sex specific hormonal influences. Choline rich foods such

as eggs, liver, salmon, poultry, soybeans and legumes are recommended to support methylation and lipid metabolism pathways.

The effects of choline on hepatic steatosis (HS) appear genotype-dependent:

-Men with GG genotype are advised to moderate their choline intake, as daily consumption exceeding 424 mg has been

associated with a 3.7-fold increased risk of hepatic steatosis (Wu et al., 2023).

-Women with theGG genotype may benefit from higher choline intake, with intakes above 448mg/day linked to a 79% reduction

in HS risk.

methionine is critical for maintaining methylation efficiency. An imbalance in the choline-to-betaine ratio may contribute to

increased cancer risk, particularly within the digestive system (Zhang et al., 2024).

Recommended strategies include:

Regular assessment of plasma choline and beta in levels to evaluate choline to beta in ratios.

Periodic liver function tests to detect early signs of hepatic dysfunction in genetically predisposed individuals.

Moreover, adopting a nutritionally balanced diet, maintaining a healthy body weight, and limiting alcohol consumption are key

lifestyle interventions to support liver health and reduce metabolic burden (Piras et al.,2022).

Future Scope

Advancing the integration of PEMT rs7946 genotyping into public health and clinical nutrition offers immense potential for

preventing choline deficiency related conditions. Future studies should examine gene-diet interactions across diverse ethnic

INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,

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dietary choline requirements, particularly among Aallele carriers and women with low estrogen levels. Personalised nutrition

4. Harrison, C., Jones, P., & Zeisel, S. (2020). Estrogen regulation of PEMT and implications for choline requirements in