MTRR Homozygous GG Genotype Prevalence
The MTRR homozygous GG genotype is relatively uncommon, occurring in approximately 5-8% of most populations studied, though this varies significantly by ethnicity and geographic region.
Population-Specific Frequencies
The prevalence of the MTRR c.66A>G (rs1801394) homozygous GG genotype shows substantial geographic and ethnic variation:
Chinese Han Population
Indian Populations
- Eastern Uttar Pradesh (Sunni Muslim): 50% - notably the highest reported frequency, with the G allele frequency at 0.705 3
- Yadav population: 28% 4
- Scheduled Caste population: 36% 4
Clinical Populations
- Pediatric ALL patients: 4.65% (significantly lower than the 20.67% in healthy controls in one study) 5
Key Clinical Context
The G allele is generally more common than the homozygous GG genotype across populations. The heterozygous AG genotype typically represents 39-60% of individuals, while the homozygous AA genotype ranges from 12-55% depending on the population 1, 2, 4.
Important Caveats
- Population stratification matters significantly: Indian Muslim populations show dramatically higher GG frequencies (up to 50%) compared to Chinese Han populations (5-8%) 3, 1
- The MTRR 66GG genotype has been associated with elevated homocysteine levels and may contribute to various health outcomes including congenital heart disease risk 6, 7
- Recent studies suggest potential protective effects: One pediatric ALL study found lower GG frequency in patients versus controls, though this association was not statistically significant 5
Geographic Variation Within China
Even within the Chinese Han population, significant regional differences exist. The frequency in Zhengzhou (5.4%) was significantly lower than in Deyang (8.2%), demonstrating that even within ethnically similar populations, geographic factors influence allele distribution 1.
In summary, while MTRR homozygous GG is relatively uncommon in most populations at 5-8%, it can reach frequencies as high as 50% in specific ethnic groups, particularly certain Indian populations. The heterozygous AG genotype is consistently the most common variant across all studied populations.