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Nutrición Hospitalaria

versión On-line ISSN 1699-5198versión impresa ISSN 0212-1611

Nutr. Hosp. vol.39 no.1 Madrid ene./feb. 2022  Epub 04-Abr-2022 


Discordance between allelic and genotype frequencies for CD36 rs3211938 between Mexican mestizo samples: sample bias, genotyping error, or microevolution?

Sergio V Flores1  , Ángel Roco Videla2  3  , Omar Silva González4 

1Dirección de Desarrollo y Postgrado. Universidad Autónoma de Chile. Santiago, Chile

2Programa de Mágister en Ciencias Químico-Biológicas. Facultad de Ciencias de Salud. Universidad Bernardo O'Higgins. Santiago, Chile

3Department of Civil Engineering. Facultad de Ingeniería. Universidad Católica de la Santísima Concepción. Concepción, Chile

4Facultad de Medicina Veterinaria y Agronomía. Universidad de las Américas. Santiago, Chile

Dear Editor,

The article published by Martín-Márquez et al. (1) shows evidence on the association between the GT CD36 rs3211938 genotype and high levels of glucose, ox-LDL, HDL-cholesterol, and IR, and increased BMI in Mexican mestizo T2DM (type-2 diabetes mellitus) patients from western Mexico. The criteria used to define “mestizo” (2) allow further research to survey those statistical associations in other Latin American mestizo populations.

The cited work did not address the Hardy-Weinberg (H-W) equilibrium to contrast the concordance between allelic and genotype frequencies under the null hypothesis of absence of evolutionary factors operating on populations. The H-W test has been used to detect sampling bias (3) and genotyping errors (4). In addition, the allelic and genotype frequencies were not contrasted with data reported by other studies.

We collected information on the variation of CD36 rs3211938 from the public database 1000 Genomes (1 kg)(5; and the allelic frequencies are different from those reported by Martín-Marquez et al. In the four Latin American population samples contained in 1 kg (n = 692 individuals), including Mexico, Colombia, Peru, and Puerto Rico, only one allele G, from a Peruvian individual, was found. Thus, the frequency of the allele G is 0 % in Mexico and 0.0007 % in the pooled Latin American samples from 1 kg. In Europe, East Asia, and South Asia that frequency is 0 % both in 1 kg and the ALFRED database (6; In the article here discussed, the frequencies of G were 10.34 % and 25.44 % in the NT2DM (non-type-2 diabetes mellitus) and T2DM samples, respectively.

We analyzed genic differentiation using the exact G test implemented in Popgene (7). Significant differentiation was found between the three pairwise comparisons: NT2DM vs. TD2M, p = 0.02204; NT2DM vs. Mexico from 1 kg (MXL), p = 0.00013; NT2DM vs. MXL, p = 0. Genotypic differentiation showed the same pattern: NT2DM vs. TD2M, p = 0.01100; NT2DM vs. MXL, p = 0.00010; NT2DM vs. MXL, p = 0.

Finally, the H-W equilibrium is rejected in the T2DM sample, showing heterozygote excess (Table I). In summary, our findings suggest a sample bias or genotyping error. An alternative, less plausible hypothesis is the occurrence of micro-evolutionary processes on CD36 rs3211938 in western Mexico, increasing the frequency of allele G and heterozygosity. Further research is needed in order to understand the discordance between allelic and genotype frequencies observed in the article by Martín-Márquez et al., the differences among datasets, and their implications on the role of CD36 rs3211938 on the metabolic profile of Mexican mestizo populations.

Table I.  Hardy-Weinberg analysis for CD36 rs3211938 in Mexican mestizo populations 

NT2DM: non-type-2 diabetes mellitus sample; T2DM: type-2 diabetes mellitus sample; *p value < 0.05; Pchi = p value for the Chi2 test; Pexact = p value for the Fischer exact test implemented in Genpop.


1. Martín-Márquez BT, Sandoval-Garcia F, Vazquez-Del Mercado M, Martínez-García E-A, Corona-Meraz F-I, Fletes-Rayas A-L, et al. Contribution of rs3211938 polymorphism at CD36 to glucose levels, oxidized low-density lipoproteins, insulin resistance, and body mass index in Mexican mestizos with type-2 diabetes from western Mexico. Nutr Hosp 2021;38(4):742-8. DOI:10.20960/nh.03447 [ Links ]

2. Gorodezky C, Alaez C, Vázquez-García MN, de la Rosa G, Infante E, Balladares S, et al. The Genetic structure of Mexican Mestizos of different locations:tracking back their origins through MHC genes, blood group systems, and microsatellites. Human Immunology 2001;62(9):979-91. DOI:10.1016/s0198-8859(01)00296-8 [ Links ]

3. Bourgain C, Abney M, Schneider D, Ober C, McPeek MS. Testing for Hardy-Weinberg Equilibrium in Samples With Related Individuals. Genetics 2004;168(4):2349-61. DOI:10.1534/genetics.104.031617 [ Links ]

4. Hosking L, Lumsden S, Lewis K, Yeo A, McCarthy L, Bansal A, et al. Detection of genotyping errors by Hardy-Weinberg equilibrium testing. Eur J Hum Genet 2004;12(5):395-9. DOI:10.1038/sj.ejhg.5201164 [ Links ]

5. Cheung K-H. ALFRED:an allele frequency database for diverse populations and DNA polymorphisms. Nucleic Acids Research 2000;28(1):361-3. DOI:10.1093/nar/28.1.361 [ Links ]

6. Auton A, Abecasis GR, Altshuler DM, Durbin RM, Abecasis GR, et al. A global reference for human genetic variation. Nature 2015;526(7571):68-74. DOI:10.1038/nature15393 [ Links ]

7. Rousset F. Genepop'007:a complete reimplementation of the Genepop software for Windows and Linux. Mol Ecol Resources 2008;8(1):103-6. DOI:10.1111/j.1471-8286.2007.01931.x [ Links ]

Conflicts of interest:

the authors have no conflicts of interest to declare.

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