High Prevalence of ITPA Alleles Associated with Ribavirin-Induced Hemolytic Anemia Among Mexican Population

BACKGROUND

The prevalence of two functional polymorphisms (rs1127354 and rs7270101) of the inosine triphosphatase (ITPA) gene associated with ribavirin-induced hemolytic anemia (RIHA) during antiviral therapy for hepatitis C virus (HCV) infection varies by ethnicity. In Mexico, the distribution of these polymorphisms among Native Amerindians (NA) and admixed population (Mestizos) is unknown. This study aimed to determine the prevalence of the ITPA polymorphisms among healthy NA and Mestizos, as well as in HCV patients from West Mexico.

MATERIAL AND METHODS

In a cross-sectional study, 600 unrelated subjects (322 Mestizos, 100 NA, and 178 treatment-naïve, HCV-infected Mestizos patients) were enrolled. A medical history was registered. ITPA genotype was determined by Real-Time PCR. Fst-values and genetic relatedness between study and reference populations were assessed.

RESULTS

The frequency of the risk genotypes rs1127354CC and rs7270101AA was higher among NA (98-100%) than in Mestizos (87-92.9%), (p < 0.05). The NA presented the highest prevalence of the rs1127354CC genotype reported worldwide. The Fst-values revealed a genetic relatedness among Mexican NA, South Americans and African populations (p > 0.05). The frequency of the predicted risk for RIHA was higher among NA (98%) than in Mestizos (80.5%) and HCV-infected patients (81.5%) (p < 0 .01). The CC/AA alleles were associated with lower values of total bilirubin, aspartate/alanine aminotransferases, and aspartate-to-platelet-ratio-index score among HCV-patients.

CONCLUSION

A high prevalence of the ITPA polymorphisms associated with RIHA was found in Mexican NA. These polymorphisms could be a useful tool for evaluating potential adverse effects and the risk or benefit of antiviral therapy in Mexicans and other admixed populations.

Association of Lactase Persistence Genotypes with High Intake of Dairy Saturated Fat and High Prevalence of Lactase Non-Persistence among the Mexican Population

BACKGROUND/AIM

Lactase (LCT) -13910 C>T and -22018 G>A polymorphisms associated with the lactase non-persistence (LNP)/persistence (LP) phenotypes vary globally. LP has been associated with obesity in Europeans. However, it has not been genetically evaluated in Mexico, a country with admixed population, recent introduction of dairy, and a high prevalence of obesity. Thus, we aimed to determine the distribution of the LCT polymorphisms and their association with the nutritional profile of West Mexico's populations.

METHODS

Genotyping of 1,196 individuals (natives and mestizos) was carried out by a Taqman allelic discrimination assay. Descriptive statistics and interpopulation analyzes were performed by SPSS, Arlequin, and Structure software. Demographic, anthropometric, biochemical and dietary data were analyzed in 212 mestizos.

RESULTS

LNP genotypes mainly prevailed (CC 68.7% and GG 68.2%); both predominated in native Huicholes and Nahuas (>97.7%). Among the mestizos, the LP genotypes were associated with a higher intake of saturated fat (9.9 ± 3.9% vs. 8.5 ± 4.0%, p = 0.018; OR = 2.55, 95% CI 1.29-5.03, p = 0.006) and a daily/more frequent consumption of dairy (88.8 vs. 78.0%; p = 0.049) than LNP genotypes.

CONCLUSION

The LNP trait was predominant in Mexicans with a major Amerindian ancestry. A daily consumption of dairy was associated with a higher intake of saturated fat in LP individuals.

Association with Spontaneous Hepatitis C Viral Clearance and Genetic Differentiation of IL28B/IFNL4 Haplotypes in Populations from Mexico

AIM

To analyze the genetic heterogeneity of the Amerindian and admixed population (Mestizos) based on the IL28B (rs12979860, rs8099917) and IFNL4 (rs368234815) haplotypes, and their association with spontaneous clearance (SC) and liver damage in patients with hepatitis C infection from West Mexico.

METHODS

A total of 711 subjects from West Mexico (181 Amerindians and 530 Mestizos) were studied for the prevalence of IL28B (rs12979860C/T, rs8099917G/T) and IFNL4 (rs368234815∆G/TT) genotypes. A case-control study was performed in 234 treatment-naïve HCV Mestizos (149 chronic hepatitis C and 85 with SC) for the association of haplotypes with SC and liver damage. A real-time PCR assay was used for genotyping, and transitional elastography staged liver damage.

RESULTS

Significant Fst-values indicated differentiation between the studied populations. The frequencies of the protective C, T, TT alleles were significantly lower in the Amerindians than in Mestizos (p<0.05). The r2 measure of linkage disequilibrium was significant for all variants and the T/G/ΔG risk haplotype predominated in Amerindians and secondly in Mestizos. The protective C/T/TT haplotype was associated with SC (OR = 0.46, 95% IC 0.22-0.95, p = 0.03) and less liver damage (OR = 0.32, 95% IC 0.10-0.97, p = 0.04) in chronic patients. The Structure software analysis demonstrated no significant differences in ancestry among SC and chronic patients.

CONCLUSIONS

West Mexico's population is genetically heterogeneous at the IL28B/IFNL4 polymorphisms. The T/G/ΔG high-risk haplotype predominated in Amerindians and the beneficial alternative haplotype in Mestizos. The C/T/TT haplotype was associated with SC and less liver damage in chronically infected Mestizo patients.