Effect of APOB gene polymorphisms on body mass index, blood pressure, and total cholesterol levels: A cross-sectional study in Mexican population.

APOB gene polymorphisms are considered risk factors for the development of dyslipidemia, hypertension, and cardiovascular disease (CVD) in several populations. In Mexico, these pathologies are frequent and studies regarding this gene are scarce. The aim of this cross-sectional study was to determined genotype, allele, and haplotype frequencies of APOB polymorphisms and performed analyses of association among the biochemical, hemodynamic, anthropometrical, and genetic variables. Blood samples were taken from 361 subjects from unselected Mexican population for biochemical analysis and for deoxyribonucleic acid extraction; besides blood pressure and body mass index (BMI) were measured. APOB polymorphisms rs934197, rs533617, rs693, and rs1042031 were genotyped by polymerase chain reaction (PCR)-restriction fragment length polymorphism; whereas, rs17240441 and c.66_67insCTGCTG were genotyped by PCR followed by electrophoresis. Genotype and allele frequencies were obtained by simple counting and deviations from Hardy-Weinberg equilibrium (HWE) were calculated by chi-square test. The effect of the polymorphisms on the quantitative variables was determined using analysis of variance, Student's t test, Pearson's and Spearman's correlations and multiple linear regression models. All the polymorphisms were within HWE. Frequencies of mutated alleles were highly heterogeneous: rs934197-T 33.6%, rs17240441-D 39.3%, c.66_67insCTGCTG-I 3.9%, rs533617-G 0.9%, rs693-T 40.5%, and rs1042031-G 17.3%. Chronic degenerative diseases were frequent in the studied population: overweight-obesity 55.1%, dyslipidemia 45.8%, and hypertension 23.5%. The association analyses showed that despite adjustments for age and sex the mutated alleles rs934197-T, rs1042031G, c.66_67-insCTGCTG-I, and rs533617-G, were related to lower values of BMI, total cholesterol (TC), systolic blood pressure, and diastolic blood pressure, respectively. All polymorphisms analyzed except rs533517 and c.66_67insCTGCTG showed high frequencies of the mutated allele, making them useful for association studies. Our results revealed that, APOB gene polymorphisms could be contributing to the development of several chronic diseases, such as essential hypertension, dyslipidemias, obesity, among others. However, specific studies with each pathology are needed to know the possible implications of the polymorphisms.

Biochemical, Clinical, and Genetic Characteristics of Mexican Patients with Primary Hypertriglyceridemia, Including the First Case of Hyperchylomicronemia Syndrome Due to GPIHBP1 Deficiency.

Primary hypertriglyceridemia (PHTG) is characterized by a high concentration of triglycerides (TG); it is divided between familial hyperchylomicronemia syndrome and multifactorial chylomicronemia syndrome. In Mexico, hypertriglyceridemia constitutes a health problem in which the genetic bases have been scarcely explored; therefore, our objective was to describe biochemical-clinical characteristics and variants in the APOA5, GPIHBP1, LMF1, and LPL genes in patients with primary hypertriglyceridemia. Thirty DNA fragments were analyzed using PCR and Sanger sequencing in 58 unrelated patients. The patients' main clinical-biochemical features were hypoalphalipoproteinemia (77.6%), pancreatitis (18.1%), and a TG median value of 773.9 mg/dL. A total of 74 variants were found (10 in APOA5, 16 in GPIHBP1, 34 in LMF1, and 14 in LPL), of which 15 could be involved in the development of PHTG: 3 common variants with significative odds and 12 heterozygous rare pathogenic variants distributed in 12 patients. We report on the first Mexican patient with hyperchylomicronemia syndrome due to GPIHBP1 deficiency caused by three variants: p.R145*, p.A154_G155insK, and p.A154Rfs*152. Moreover, eleven patients were heterozygous for the rare variants described as causing PHTG and also presented common variants of risk, which could partially explain their phenotype. In terms of findings, two novel genetic variants, c.-40_-22del LMF1 and p.G242Dfs*10 LPL, were identified.

Association of the -629C>A (rs1800775) CETP Polymorphism with the Development of Essential Hypertension in Mexican Population.

Introduction: Polymorphisms in the CETP gene promoter have been associated with cardiovascular risk and lipid alterations; however, their role in the development of hypertension has not been extensively explored. We evaluated four polymorphisms of the CEPT gene -827C>T, -631C>A, -630C>A, and -629C>A in patients with essential hypertension (EH). Materials and Methods: A total of 160 hypertensive (HT) patients and 160 normotensive (NT) individuals were studied. Blood pressure was measured and blood samples were collected for biochemical anlayses and DNA extraction. Polymorphisms were identified using Sanger sequencing. Genotype, genotype combination, allele, and haplotype frequencies were analyzed. Associations between the SNPs and EH were explored using multiple linear regression models. Results: Under the dominant model, the -629A allele reduced the odds of having EH (odds ratio [OR] = 0.58, 95% confidence interval [CI], 0.34-0.98; p = 0.04), whereas the genotype combination -631CC/-629CC increased the risk of HT (OR = 2.21, 95% CI, 1.23-3.95, p = 0.008). In HT patients, the -629A allele was associated with increased insulin levels (ß = 4.0, 95% CI, 1.21-6.68, p = 0.005), and homeostatic model assessment of insulin resistance (ß = 0.9, 95% CI, 0.17-1.72, p = 0.018), and in NT individuals it was associated with increased high-density lipoprotein cholesterol levels (ß = 3.0, 95% CI, 0.20-5.78, p = 0.036). Conclusion: The CETP -629A allele reduces the odds of having essential arterial hypertension in the Mexican population. Moreover, it exerts a variable effect on diverse biomarkers analyzed in both NT and HT groups.

LDLR Gene Mutation p.Asp360His and Familial Hypercholesterolemia in a Mexican Community.

BACKGROUND: Familial hypercholesterolemia (FH) is an autosomal dominant disease characterized by an increased LDL-cholesterol (LDLc) serum concentration and premature cardiovascular disease. Screening of small populations where at least one homozygous (HoFH) patient has been identified may be a proper approach for detecting FH patients. Previously, we reported an HoFH patient carrying the mutation p.Asp360His LDLR, who was born in the Mexican community El Triunfo (Quimixtlan, Puebla). AIM OF THE STUDY: To identify patients with familial hypercholesterolemia in the community El Triunfo and to describe their clinical and biochemical characteristics. METHODS: We studied 308 individuals by quantifying lipid levels and by DNA sequencing. RESULTS: Sixteen of 308 individuals presented an LDLc level >170 mg/dL and all of them turned out to be heterozygous for the LDLR p.Asp360His variant. Subsequently, 34 of their first-degree relatives (mainly siblings and parents) were genotyped rendering six additional HeFH patients, which resulted in 22 carriers of the mutated allele. The study of six LDLR polymorphisms in four unrelated individuals from the community (one HoFH and three HeFH) showed the same haplotype combination, suggesting a unique ancestral origin of the mutation. CONCLUSIONS: The community El Triunfo, has the highest worldwide frequency ever reported of HeFH, with 7.14% (22/308, equivalent to 1/14 inhabitants). Since the HeFH patients showed variable biochemical expression, we suggest looking for factors with the potential to modify the phenotype. Finally, we stress the importance of establishing accurate LDLc cut-off points applicable to Mexican population for the diagnosis of FH.

Screening of LDLR and APOB gene mutations in Mexican patients with homozygous familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is an autosomal dominant disorder that causes accumulation of serum low-density lipoprotein cholesterol and premature cardiovascular disease. It is mainly related to mutations in the LDLR gene. Homozygous FH (HoFH) patients have the most severe form of the disease accounting for a worldwide prevalence of 1:1,000,000. In Mexico, at least 5 cases of HoFH have been reported. OBJECTIVE: The aim of this study was to describe the clinical, biochemical, and molecular data observed in patients with HoFH phenotype. METHODS: We included 13 patients, belonging to 11 families, with clinical and biochemical diagnoses suggestive of HoFH. Molecular analyses of the LDLR and APOB genes were performed by means of polymerase chain reaction followed by Sanger sequencing. RESULTS: The causal mutation of HoFH was found in 8 of 11 unrelated patients. Excepting 1, all were true homozygotes. Six different variants in LDLR were identified: c.-139delCTCCCCCTGC, p.Glu140Lys, p.Asp360His, p.Asn405Lys, p.Ala755Glyfs*7, and p.Leu759Serfs*6. Of these, p.Asp360His and p.Asn405Lys were detected for the first time in Mexico; p.Leu759Serfs*6 showed to be the most frequent (43.7% of the alleles 7/16), and c.-139delCTCCCCCTGC is a new variant located in the promoter region. CONCLUSIONS: This work increases knowledge of biochemical and genetic features in Mexican patients with HoFH. A novel mutation in the LDLR gene promoter was detected: c.-139delCTCCCCCTGC, which possibly inhibits its expression.

Two novel mutations in the ABCG5 gene, c.144 -1G>A and c.1523 delC, in a Mexican family with sitosterolemia.

Sitosterolemia is a disease characterized by an intestinal hyperabsorption of plant sterols and cholesterol. Affected individuals have mutations in both alleles of either ABCG5 or ABCG8 genes, leading to a total loss of one of the proteins and subsequent functional deficiency. We here report a Mexican family with clinical and biochemical features of sitosterolemia carrying 2 new mutations of the ABCG5 gene. Concentrations of sitosterol, campesterol, and cholesterol were found to be higher for the index case (a 10-year-old girl) than for her also affected sibling (64.1 vs 19 mg/dL, 32 vs 12.1 mg/dL, and cholesterol 295 vs 235 mg/dL, respectively). Both individuals showed 2 new ABCG5 gene mutations identified by sequencing, which is concordant with their biochemical diagnosis of sitosterolemia. The first mutation was a c.144 -1G>A transition that disrupts the intron 1 splicing acceptor site. The second mutation is the deletion c.1523 delC, which occurred in exon 11, causing an amino acid change at codon 510 (p.His510Thr) and a stop codon at codon 511 (p.Leu511X). The father is heterozygote for the mutation c.144 -1G>A, whereas the mother is heterozygote for the mutation c.1523 delC. In conclusion, we here report the first case of a Mexican family with sitosterolemia carrying two new ABCG5 gene mutations.