Erika Martinez-Lopez

Hepatitis B virus infection in Latin America: A genomic medicine approach

Hepatitis B virus (HBV) infection is the leading cause of severe chronic liver disease. This article provides a critical view of the importance of genomic medicine for the study of HBV infection and its clinical outcomes in Latin America. Three levels of evolutionary adaptation may correlate with the clinical outcomes of HBV infection. Infections in Latin America are predominantly of genotype H in Mexico and genotype F in Central and South America; these strains have historically circulated among the indigenous population. Both genotypes appear to be linked to a benign course of disease among the native and mestizo Mexicans and native South Americans. In contrast, genotypes F, A and D are common in acute and chronic infections among mestizos with Caucasian ancestry. Hepatocellular carcinoma is rare in Mexicans, but it has been associated with genotype F1b among Argentineans. This observation illustrates the significance of ascertaining the genetic and environmental factors involved in the development of HBV-related liver disease in Latin America, which contrast with those reported in other regions of the world.

Association of the ε2 Allele of Apoe Gene to Hypertriglyceridemia and to Early‐Onset Alcoholic Cirrhosis

BACKGROUND The diverse incidence of alcoholic cirrhosis around the world and the fact that not all alcoholic drinkers develop liver disease indicates that genetic and environmental factors play an important role in the development of liver cirrhosis. Lipids participate in early stages of alcoholic cirrhosis. Therefore variations in the plasma lipid profile due to primary (genetic) or secondary (environmental) dyslipidemia could affect the development of liver disease. The aim of this study was to analyze the lipid profile and apolipoprotein E (APOE) polymorphism in patients with alcoholic liver cirrhosis (AC) and determine the risk associated with genotype polymorphism with the onset of alcoholic cirrhosis. METHODS In a case and control study, 86 patients with AC divided into hyperlipidemic (H) and non-hyperlipidemic (non-H) groups, and 133 healthy individuals (C) matched by age and sex were studied. Lipid profile and liver function tests were measured by enzymatic methods. The APOE genotypes were identified by PCR-RFLPs. RESULTS A statistically significant increase of the APOE*2 allele and genotypes 2/2, 2/3, and 2/4 was present in AC patients compared to C group. A hyperlipidemic state characterized by increased levels of triglycerides and apolipoprotein B (APOB) and a decrease of high density lipoprotein-cholesterol (HDL-c) was detected in young-aged patients (31.2 +/- 6.2 years old vs. 46.3 +/- 12.5 years old). In this group, hypertriglyceridemia was closely associated to APOE*2 allele and to an early onset of liver cirrhosis. By contrast, APOE*4 allele was associated with a longer duration of alcohol intake (>20 years) in the non-H group. CONCLUSIONS This study shows the association of hypertriglyceridemia and APOE allele with the early onset of alcoholic liver cirrhosis, and the interaction between environmental factors, such as duration of alcohol abuse and amount of alcohol intake, and genetic factors (APOE*2 allele) on the hypertriglyceridemic process.

Sweet Taste Receptor TAS1R2 Polymorphism (Val191Val) Is Associated with a Higher Carbohydrate Intake and Hypertriglyceridemia among the Population of West Mexico.

Some high-carbohydrate diets may lead to obesity and multiple metabolic disorders, including hypertriglyceridemia (HTG). This lipid abnormality is considered an important risk factor for cardiovascular disease and type 2 diabetes. The sweet taste receptor TAS1R2 polymorphism (Ile191Val) has been reported to be associated with carbohydrate intake. The aim of this study was to analyze the association of the TAS1R2 gene polymorphism with carbohydrate intake and HTG among the population of West Mexico. In a cross-sectional study, 441 unrelated subjects were analyzed for TAS1R2 genotypes (Ile/Ile, Ile/Val and Val/Val) by an allelic discrimination assay. Biochemical tests and a three-day food record were assessed. The Val/Val genotype carriers had a higher intake of total carbohydrates, fiber and servings of cereals and vegetables than the other genotype carriers. The Val/Val genotype conferred a higher risk for HTG than the Ile/Val and Ile/Ile genotypes (OR = 3.26, 95%CI 1.35–7.86, p = 0.006 and OR = 2.61, 95%CI 1.12–6.07, p = 0.02, respectively). Furthermore, the Val/Val genotype was associated with approximately 30% higher triglycerides compared with Ile/Val and Ile/Ile genotypes (β = 44.09, 95%CI 9.94–78.25, p = 0.01 and β = 45.7, 95%CI 10.85–80.54, p = 0.01, respectively). In conclusion, the Val/Val genotype of TAS1R2 was associated with a higher carbohydrate intake and HTG.

Immunologic, metabolic and genetic factors in hepatitis C virus infection.

The mechanisms that regulate disease progression during hepatitis C virus (HCV) infection and the response to treatment are not clearly identified. Numerous studies have demonstrated that a strong host immune response against HCV favors HCV clearance. In addition, genetic factors and metabolic machinery, particularly cholesterol modulation, are involved in HCV infection. It is likely that the interplay between all of these factors contributes to the outcome of HCV infection. In recent years, the world has experienced its largest epidemic of obesity. Mexico and the United States are the leading sufferers from this epidemic at the global level. Obesity is associated with the development of numerous pathologies including hypercholesterolemia which is one of the eight most important risk factors for mortality in Mexico. This may be related to the course of HCV infection in this population. Here, we focus on the urgent need to study the progression of HCV infection in relation to ethnic characteristics. Discoveries are discussed that hold promise in identifying immune, metabolic and genetic factors that, in conjunction, could be therapeutic targets or predictors of the progression of HCV infection.

Effect of Ala54Thr polymorphism of FABP2 on anthropometric and biochemical variables in response to a moderate-fat diet

OBJECTIVE To analyze the effect of the fatty acid-binding protein (FABP2) gene Ala54Thr polymorphism on anthropometric and biochemical variables in response to a moderate-fat diet in overweight or obese subjects. METHODS One hundred nine subjects with a body mass index ≥ 25 kg/m(2) were studied. Participants underwent a dietary intervention that consisted of 30% fat (saturated fat <7% of total calories), 15% protein, and 55% carbohydrates. The FABP2 genotypes were analyzed by polymerase chain reaction-restriction fragment length polymorphism. Anthropometric and biochemical data were measured at baseline, 1 mo, and 2 mo of nutritional intervention. RESULTS The mean age was 38.6 ± 11.3 y and the mean body mass index 32.7 ± 6.1 kg/m(2), with 20 men (18%) and 89 women (82%). Fifty-three patients (48.6%) had genotype Ala54Ala (wild-type group) and 56 patients had genotype Ala54Thr/Thr54Thr (51.4%, mutant group). At baseline, no significant difference was found between the FABP2 genotypes groups, except for the carbohydrate intake and resting metabolic rate, which were higher in the Ala54Thr/Thr54Thr group (P < 0.05). At 2 mo, participants had lost 6.8% of their initial weight. The Ala54Thr/Thr54Thr group compared with the Ala54Ala group showed significant decreases in the parameters of weight (-7.5 versus -4.2 kg), body mass index (-2.1 versus -1.2 kg/m(2)), waist circumference (-7.6 versus -5.2 cm), waist-to-hip ratio (-0.04 versus -0.02), and C-reactive protein (-1.4 versus -0.76 mg/L), respectively (P < 0.05). After the resting metabolic rate was adjusted, the decreases in waist circumference, waist-to-hip ratio, and C-reactive protein remained significant between the two groups. CONCLUSIONS This study showed that the Thr54 allele carriers responded better to a moderate-fat diet.

Genetic, metabolic and environmental factors involved in the development of liver cirrhosis in Mexico.

Liver cirrhosis (LC) is a chronic illness caused by inflammatory responses and progressive fibrosis. Globally, the most common causes of chronic liver disease include persistent alcohol abuse, followed by viral hepatitis infections and nonalcoholic fatty liver disease. However, regardless of the etiological factors, the susceptibility and degree of liver damage may be influenced by genetic polymorphisms that are associated with distinct ethnic and cultural backgrounds. Consequently, metabolic genes are influenced by variable environmental lifestyle factors, such as diet, physical inactivity, and emotional stress, which are associated with regional differences among populations. This Topic Highlight will focus on the genetic and environmental factors that may influence the metabolism of alcohol and nutrients in the setting of distinct etiologies of liver disease. The interaction between genes and environment in the current-day admixed population, Mestizo and Native Mexican, will be described. Additionally, genes involved in immune regulation, insulin sensitivity, oxidative stress and extracellular matrix deposition may modulate the degree of severity. In conclusion, LC is a complex disease. The onset, progression, and clinical outcome of LC among the Mexican population are influenced by specific genetic and environmental factors. Among these are an admixed genome with a heterogenic distribution of European, Amerindian and African ancestry; a high score of alcohol consumption; viral infections; a hepatopathogenic diet; and a high prevalence of obesity. The variance in risk factors among populations suggests that intervention strategies directed towards the prevention and management of LC should be tailored according to such population-based features.

Genetic Variant in the CD36 Gene (rs1761667) is Associated with Higher Fat Intake and High Serum Cholesterol among the Population of West Mexico

High-fat diets lead to obesity and metabolic disorders. The rs1761667 CD36 gene polymorphism may predict the preference for dietary fat. Aim: To determine the association of the CD36 gene polymorphism with fat intake and lipid abnormalities in subjects from West Mexico. Methods: In a cross-sectional study, 441 subjects were divided into normal weight, overweight and obese groups. Real-time PCR determined CD36 genotypes (AA, AG, and GG). Lipid biochemical tests and a 3-day food record were assessed. Results: The allele of CD36 was prevalent in 57.1% (n=252) of the total cases. The overweight A/A subjects had a significant higher intake of calories, protein, total fat, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) than the other genotype carriers. Furthermore, high serum cholesterol levels were associated with the A/A genotype than to the A/G genotype carriers (OR=2.75, CI 1.33-5.69; p=0.005). Conclusions: The allele of CD36 was predominant in subjects from West Mexico. In addition, a high-fat diet and high serum cholesterol levels were associated with the A/A genotype.

Association of the T54 allele of the FABP2 gene with cardiovascular risk factors in obese Mexican subjects

Genetic predisposition to cardiovascular risk may vary between different ethnic groups. We studied the effect of the FABP2 A54T polymorphism on biochemical and anthropometric cardiovascular risk factors in 114 obese Mexican subjects. The mean age of the patients studied was 36.8±13.3 years. Insulin resistance was present in 47%, hypercholesterolaemia in 49% and hyper-triglyceridaemia in 45%. Frequency of the FABP2 genotype was 39% AA, 54.8% AT and 6.2% TT. The AT/TT group showed an increase in body mass index (34±7.1 vs. 31±4.8 kg/m2), waist circumference (101±15.7 vs. 96.5±15.8 cm), triglycerides (145±60.8 vs. 127±79.4 mg/dL; 1.64±0.67 vs. 1.43±0.89 mmol/L), total cholesterol (176±39.4 vs. 164±38.2 mg/dL; 4.55±1.02 vs. 4.24±0.99 mmol/L), LDL (121±24.2 vs. 111±25.9 mg/dL; 3.13±0.62 vs. 2.88±0.67 mmol/L) and VLDL (28.8±12.1 vs. 25.1±16.1 mg/dL; 0.74±0.31 vs. 0.64±0.41 mmol/L) compared to the AA group (p<0.05). The AT/TT group had greatly increased cardiovascular risk, with an OR of 7.56 (95% CI, 1.82-36.24; p<0.001) compared to the AA group. Our results suggest that A54T polymorphism of the FABP2 gene is associated with cardiovascular disease risk in obese subjects.

Central Adiposity and Mortality after First-Ever Acute Ischemic Stroke

Background: The waist-to-height ratio (WHtR) may be a better adiposity measure than the body mass index (BMI). We evaluated the prognostic performance of WHtR in patients with acute ischemic stroke (AIS). Methods: First, we compared WHtR and BMI as adiposity measures in 712 healthy adults by tetrapolar bioimpedance analysis. Thereafter, baseline WHtR was analyzed as predictor of 12-month all-cause mortality in 821 Mexican mestizo adults with first-ever AIS by a Cox proportional hazards model adjusted for baseline predictors. Results: In healthy individuals, WHtR correlated higher than BMI with total fat mass and showed a higher accuracy in identifying a high percentage of body fat (p < 0.01). In AIS patients a U-shaped relationship was observed between baseline WHtR and mortality (fatality rate 29.1%). On multivariate analysis, baseline WHtR ≤0.300 or >0.800 independently predicted 12-month all-cause mortality (hazard ratio 1.91, 95% confidence interval 1.04-3.51). BMI was not associated with mortality, tested either as continuous, binomial or stratified variable. Conclusion: WHtR is a modifiable risk factor that accurately demonstrates body fat excess. Extreme WHtR values were associated with increased 12-month all-cause mortality in Mexican mestizo patients with AIS. No survival advantage was found with high WHtR as the pragmatic indicator of obesity in this population.

CD36 genetic variation, fat intake and liver fibrosis in chronic hepatitis C virus infection

AIM To analyze the association of the CD36 polymorphism (rs1761667) with dietary intake and liver fibrosis (LF) in chronic hepatitis C (CHC) patients. METHODS In this study, 73 patients with CHC were recruited. The CD36 genotype (G > A) was determined by a TaqMan real-time PCR system. Dietary assessment was carried out using a three-day food record to register the daily intake of macronutrients. Serum lipids and liver enzymes were measured by a dry chemistry assay. LF evaluated by transient elastography (Fibroscan(®)) and APRI score was classified as mild LF (F1-F2) and advanced LF (F3-F4). RESULTS Overall, the CD36 genotypic frequencies were AA (30.1%), AG (54.8%), and GG (15.1%), whereas the allelic A and G frequencies were 57.5% and 42.5%, respectively. CHC patients who were carriers of the CD36 AA genotype had a higher intake of calories attributable to total fat and saturated fatty acids than those with the non-AA genotypes. Additionally, aspartate aminotransferase (AST) serum values were higher in AA genotype carriers compared to non-AA carriers (91.7 IU/L vs 69.8 IU/L, P = 0.02). Moreover, the AA genotype was associated with an increase of 30.23 IU/L of AST (β = 30.23, 95%CI: 9.0-51.46, P = 0.006). Likewise, the AA genotype was associated with advanced LF compared to the AG (OR = 3.60, 95%CI: 1.16-11.15, P = 0.02) or AG + GG genotypes (OR = 3.52, 95%CI: 1.18-10.45, P = 0.02). CONCLUSION This study suggests that the CD36 (rs1761667) AA genotype is associated with higher fat intake and more instances of advanced LF in CHC patients.