Identification and functional analysis of missense mutations in the lecithin cholesterol acyltransferase gene in a Chilean patient with hypoalphalipoproteinemia.

BACKGROUND: Lecithin-cholesterol acyltransferase (LCAT) is a plasma enzyme that esterifies cholesterol in high- and low-density lipoproteins (HDL and LDL). Mutations in LCAT gene causes familial LCAT deficiency, which is characterized by very low plasma HDL-cholesterol levels (Hypoalphalipoproteinemia), corneal opacity and anemia, among other lipid-related traits. Our aim is to evaluate clinical/biochemical features of a Chilean family with a proband showing clinical signs of familial LCAT deficiency, as well as to identify and assess the functional effects of LCAT mutations. METHODS: An adult female proband with hypoalphalipoproteinemia, corneal opacity and mild anemia, as well as her first-degree relatives, were recruited for clinical, biochemical, genetic, in-silico and in-vitro LCAT analysis. Sequencing of exons and intron-exon boundaries was performed to identify mutations. Site-directed mutagenesis was carried out to generate plasmids containing cDNA with wild type or mutant sequences. Such expression vectors were transfected to HEK-239 T cells to asses the effect of LCAT variants in expression, synthesis, secretion and enzyme activity. In-silico prediction analysis and molecular modeling was also used to evaluate the effect of LCAT variants. RESULTS: LCAT sequencing identified rare p.V333 M and p.M404 V missense mutations in compound heterozygous state in the proband, as well the common synonymous p.L363 L variant. LCAT protein was detected in proband's plasma, but with undetectable enzyme activity compared to control relatives. HEK-293 T transfected cells with vector expression plasmids containing either p.M404 V or p.V333 M cDNA showed detectable LCAT protein expression both in supernatants and lysates from cultured cells, but with much lower enzyme activity compared to cells transfected with the wild-type sequence. Bioinformatic analyses also supported a causal role of such rare variations in LCAT lack of function. Additionally, the proband carried the minor allele of the synonymous p.L363 L variant. However, this variant is unlikely to affect the clinical phenotype of the proband given its relatively high frequency in the Chilean population (4%) and its small putative effect on plasma HDL-cholesterol levels. CONCLUSION: Genetic, biochemical, in vitro and in silico analyses indicate that the rare mutations p.M404 V and p.V333 M in LCAT gene lead to suppression of LCAT enzyme activity and cause clinical features of familial LCAT deficiency.

Defective functionality of HDL particles in familial apoA-I deficiency: relevance of alterations in HDL lipidome and proteome.

To evaluate functional and compositional properties of HDL in subjects from a kindred of genetic apoA-I deficiency, two homozygotes and six heterozygotes, with a nonsense mutation at APOA1 codon -2, Q[-2]X, were recruited together with age- and sex-matched healthy controls (n = 11). Homozygotes displayed undetectable plasma levels of apoA-I and reduced levels of HDL-cholesterol (HDL-C) and apoC-III (5.4% and 42.6% of controls, respectively). Heterozygotes displayed low HDL-C (21 ± 9 mg/dl), low apoA-I (79 ± 24 mg/dl), normal LDL-cholesterol (132 ± 25 mg/dl), and elevated TG (130 ± 45 mg/dl) levels. Cholesterol efflux capacity of ultracentrifugally isolated HDL subpopulations was reduced (up to -25%, P < 0.01, on a glycerophospholipid [GP] basis) in heterozygotes versus controls. Small, dense HDL3 and total HDL from heterozygotes exhibited diminished antioxidative activity (up to -48%, P < 0.001 on a total mass basis) versus controls. HDL subpopulations from both homozygotes and heterozygotes displayed altered chemical composition, with depletion in apoA-I, GP, and cholesteryl ester; enrichment in apoA-II, free cholesterol, and TG; and altered phosphosphingolipidome. The defective atheroprotective activities of HDL were correlated with altered lipid and apo composition. These data reveal that atheroprotective activities of HDL particles are impaired in homozygous and heterozygous apoA-I deficiency and are intimately related to marked alterations in protein and lipid composition.

Classification of metabolic syndrome according to lipid alterations: analysis from the Mexican National Health and Nutrition Survey 2006.

BACKGROUND: There are 16 possible Metabolic Syndrome (MS) combinations out of 5 conditions (glucose intolerance, low levels of high-density lipoprotein Cholesterol (HDL-C), high triglycerides, high blood pressure and abdominal obesity), when selecting those with at least three. Studies suggest that some combinations have different cardiovascular risk. However evaluation of all 16 combinations is complex and difficult to interpret. The purpose of this study is to describe and explore a classification of MS groups according to their lipid alterations. METHODS: This is a cross-sectional study with data from the Mexican National Health and Nutrition Survey 2006. Subjects (n = 5,306) were evaluated for the presence of MS; four mutually-exclusive MS groups were considered: mixed dyslipidemia (altered triglycerides and HDL-C), hypoalphalipoproteinemia: (normal triglycerides but low HDL-C), hypertriglyceridemia (elevated triglycerides and normal HDL-C) and without dyslipidemia (normal triglycerides and HDL-C). A multinomial logistic regression model was fitted in order to identify characteristics that were associated with the groups. RESULTS: The most frequent MS group was hypoalphalipoproteinemia in females (51.3%) and mixed dyslipidemia in males (43.5%). The most prevalent combination of MS for both genders was low HDL-C + hypertension + abdominal obesity (20.4% females, 19.4% males). The hypoalphalipoproteinemia group was characteristic of women and less developed areas of the country. The group without dyslipidemia was more frequent in the highest socioeconomic level and less prevalent in the south of the country. The mixed dyslipidemia group was characteristic of men, and the Mexico City region. CONCLUSIONS: A simple system to classify MS based on lipid alterations was useful to evaluate prevalences by diverse biologic and sociodemographic characteristics. This system may allow prevention and early detection strategies with emphasis on population-specific components and may serve as a guide for future studies on MS and cardiovascular risk.

[Hypertriglyceridemia and low HDL cholesterol as high impact factors for metabolic syndrome diagnosis in apparently healthy adults]. / Hipertrigliceridemia e hipoalfalipoproteinemia. Su impacto para diagnosticar síndrome metabólico.

OBJECTIVE: to determine the impact of lipid serum abnormalities and the prevalence of metabolic syndrome (MS) in healthy adults. METHODS: a cross-sectional, prospective and observational study in apparently healthy adults aged 20 to 60 years who had at least three of the following criteria: abdominal obesity (waist circumference > 102 cm in men and > 88 cm in women), triglycerides ≥ 150 mg/dL, HDL cholesterol < 40 mg/dL in men and < 50 mg/dL in women, blood pressure ≥ 130/85 mmHg and fasting glucose ≥ 110 mg/dL). RESULTS: the prevalence of MS was 20 %, being higher in women (67.7 %) than men (32.3 %). However, no dependence was found with gender (χ(2)= 2.059, p = 0.151). The age range with a higher prevalence of was 45-49 years. Low HDL cholesterol [HR = 11,059 (3.559, 34.610) p < 0.01], was present in 67.9 % of women and hypertriglyceridemia [HR = 15.53 (4.975, 48.513) p < 0.01] was present in 60.5 % of men. CONCLUSIONS: the results suggested that hypertriglyceridemia and hypoalphalipoproteinemia are high impact factors for MS in adults.

[Diagnostic criteria for hypoalphalipoproteinemia and the threshold associated with cardiovascular protection in a Mexican Mestizo population]. / Criterio diagnóstico para hipoalfalipoproteinemia y punto de corte asociado con protección cardiovascular en una población mestiza mexicana.

BACKGROUND AND OBJECTIVES: In the Mexican Mestizo and Indian populations it is unknown the diagnostic criteria (DC) and associated risk of myocardial infarction (MI) for the HDL-cholesterol (HDL-c). We aimed to establish, in a Mexican adult population without cardiovascular risk factors, their HDL-c concentrations, the DC for hypoalphalipoproteinemia and prevalence base on the percentile-10 and the risk associated with MI, as well as the threshold (TH) associated with cardiovascular protection. SUBJECTS AND METHODS: In 826 adult Mestizos, 98 Indians and 155 Mestizos with MI for the first time the average HDL-c serum concentrations were determined. Then the percentile and statistical analysis were carried out. RESULTS: The average HDL-c (mg/dl) concentrations for Mestizos and Indians were 43.2 and 37.2 and the ones inferior to the percentile-10 were <30 and <26, respectively. In Mestizos, HDL-c concentrations of ≤ 35 mg/dl (odds ratio [OR] 1.91, 95% confidence interval [95%CI] 1.3-2.8, P=.001) were associated with MI and those >35 (OR 0.52, IC 95% 0.36-0.76, P=.001) were associated with a cardiovascular protection of 52%. The hypoalphalipoproteinemia prevalences in Mestizos and Indians were: for the percentile-10 DC 9 and 11% and for the TH associated with MI ≤ 35, 26 and 54%, respectively. CONCLUSIONS: The Indians average HDL-c concentration was significantly lower (P<.003) than for Mestizos. The established DC showed that the hypoalphalipoproteinemia prevalences in both populations were similar to those for other open populations. In Mestizos, HDL-c concentrations > 35 mg/dl are protective for MI, but it will be necessary to establish this TH for the Indian population. Each population should establish its own DC for hypoalphalipoproteinemia.

The non-synonymous Arg230Cys variant (R230C) of the ATP-binding cassette transporter A1 is associated with low HDL cholesterol concentrations in Mexican adults: a population based nation wide study.

OBJECTIVE: To search for an association between the non-synonymous Arg230Cys variant (R230C) of the ATP-binding cassette transporter A1 and low HDL cholesterol levels in a Mexican, population-based nation wide survey. METHODS: The 2000 National Health Survey is a cross sectional study that included individuals from 400 cities. All individuals who had a 9-12-h fasted blood sample and a DNA sample were selected (n = 1729). These cases were randomly distributed; no bias was detected for sex, education, region or socioeconomic status. The R230C variant was genotyped using TaqMan assays. RESULTS: In individuals with the R230C/C230C genotypes (39.03 mg/dl (36.63-41.43)) lower HDL-C levels (p < 0.001) were observed compared to those with the R230R genotype (44.7 mg/dl (43.31-46.24)). The difference remained significant after adjusting for gender, body mass index and waist circumference; the mean difference in HDL cholesterol levels between alleles was 5.73 ± 1.4 mg/dl. The magnitude of the effect was significantly greater in males. The C230 allele of ABCA1 was associated with an increased risk for hypoalphalipoproteinemia (OR 1.66 (95%CI 1.08-2.54), p < 0.05). The population attributable risk (PAR) for having hypoalphalipoproteinemia of the C230 allele of the ABCA1, after considering the confounding effect of waist circumference and gender, was 12.2% (95%CI 1.4-24.2%). CONCLUSION: The non-synonymous Arg230Cys variant of ABCA1 is associated with low levels of HDL cholesterol levels in Mexican adults. The HDL cholesterol lowering effect of the variant is greater in males. The size of the effect is greater compared to that reported for other ABCA1 variants.

Total and high molecular weight adiponectin have similar utility for the identification of insulin resistance.

BACKGROUND: Insulin resistance (IR) and related metabolic disturbances are characterized by low levels of adiponectin. High molecular weight adiponectin (HMWA) is considered the active form of adiponectin and a better marker of IR than total adiponectin. The objective of this study is to compare the utility of total adiponectin, HMWA and the HMWA/total adiponectin index (SA index) for the identification of IR and related metabolic conditions. METHODS: A cross-sectional analysis was performed in a group of ambulatory subjects, aged 20 to 70 years, in Mexico City. Areas under the receiver operator characteristic (ROC) curve for total, HMWA and the SA index were plotted for the identification of metabolic disturbances. Sensitivity and specificity, positive and negative predictive values, and accuracy for the identification of IR were calculated. RESULTS: The study included 101 men and 168 women. The areas under the ROC curve for total and HMWA for the identification of IR (0.664 vs. 0.669, P = 0.74), obesity (0.592 vs. 0.610, P = 0.32), hypertriglyceridemia (0.661 vs. 0.671, P = 0.50) and hypoalphalipoproteinemia (0.624 vs. 0.633, P = 0.58) were similar. A total adiponectin level of 8.03 mug/ml was associated with a sensitivity of 57.6%, a specificity of 65.9%, a positive predictive value of 50.0%, a negative predictive value of 72.4%, and an accuracy of 62.7% for the diagnosis of IR. The corresponding figures for a HMWA value of 4.25 mug/dl were 59.6%, 67.1%, 51.8%, 73.7% and 64.2%.The area under the ROC curve of the SA index for the identification of IR was 0.622 [95% CI 0.554-0.691], obesity 0.613 [95% CI 0.536-0.689], hypertriglyceridemia 0.616 [95% CI 0.549-0.683], and hypoalphalipoproteinemia 0.606 [95% CI 0.535-0.677]. CONCLUSIONS: Total adiponectin, HMWA and the SA index had similar utility for the identification of IR and metabolic disturbances.

Prevalence of dyslipidemias in the Mexican National Health and Nutrition Survey 2006.

OBJECTIVE: To describe the prevalence of lipid abnormalities found in the Mexican National Health and Nutrition Survey 2006 (ENSANut 2006). MATERIAL AND METHODS: Information was obtained from 4 040 subjects aged 20 to 69 years, studied after a 9- to 12-hour fast. RESULTS: Median lipid concentrations were: cholesterol 198.5 mg/dl, triglycerides 139.6 mg/dl, HDL-cholesterol 39.0 mg/dl, non-HDL-cholesterol 159.5 mg/dl and LDL-cholesterol 131.5 mg/dl. The most frequent abnormality was HDL-cholesterol below 40 mg/dl with a prevalence of 60.5% (95%CI 58.2-62.8%). Hypercholesterolemia (> 200 mg/dl) had a frequency of abnormality of 43.6% (95%CI 41.4-46.0%). Only 8.6% of the hypercholesterolemic subjects knew their diagnosis. Hypertriglyceridemia (>or= 150 mg/dl) was observed in 31.5% (IC 95% 29.3-33.9%) of the population. CONCLUSIONS: The ENSANUT 2006 data confirm that the prevalence of hypoalphalipoproteinemia and other forms of dyslipidemia in Mexican adults is very high.

Prevalence of dyslipidemias in the Mexican National Health and Nutrition Survey 2006 / Prevalencia de las dislipidemias en la Encuesta Nacional de Salud y Nutrición 2006

OBJECTIVE: To describe the prevalence of lipid abnormalities found in the Mexican National Health and Nutrition Survey 2006 (ENSANut 2006). MATERIAL AND METHODS: Information was obtained from 4 040 subjects aged 20 to 69 years, studied after a 9- to 12-hour fast. RESULTS: Median lipid concentrations were: cholesterol 198.5 mg/dl, triglycerides 139.6 mg/dl, HDL-cholesterol 39.0 mg/dl, non-HDL-cholesterol 159.5 mg/dl and LDL-cholesterol 131.5 mg/dl. The most frequent abnormality was HDL-cholesterol below 40 mg/dl with a prevalence of 60.5 percent (95 percentCI 58.2-62.8 percent). Hypercholesterolemia (> 200 mg/dl) had a frequency of abnormality of 43.6 percent (95 percentCI 41.4-46.0 percent). Only 8.6 percent of the hypercholesterolemic subjects knew their diagnosis. Hypertriglyceridemia (> 150 mg/dl) was observed in 31.5 percent (IC 95 percent 29.3-33.9 percent) of the population. CONLUSIONS: The ENSANUT 2006 data confirm that the prevalence of hypoalphalipoproteinemia and other forms of dyslipidemia in Mexican adults is very high.

OBJETIVO: Presentar la prevalencia de las dislipidemias observada en la Encuesta Nacional de Salud y Nutrición 2006 (ENSANUT 2006). MATERIAL Y MÉTODOS: Se incluyeron 4040 individuos con edad entre 20 y 69 años estudiados bajo un ayuno de 9 a 12 horas. RESULTADOS: Las concentraciones medias de los lípidos sanguíneos fueron colesterol 198.5 mg/dl, triglicéridos 139.6 mg/dl, colesterol HDL 39.0 mg/dl, colesterol noHDL 159.5 mg/dl y colesterol LDL 131.5 mg/dl. La anormalidad más común fue la hipoalfalipoproteinemia (colesterol HDL< 40 mg/dl); su prevalencia fue 60.5 por ciento (IC95 por ciento 58.2-62.8 por ciento). La hipercolesterolemia (colesterol > 200 mg/dl) fue la segunda anormalidad en frecuencia, con 43.6 por ciento (IC95 por ciento 41.4-46.0 por ciento). Sólo el 8.6 por ciento de los casos conocía su diagnóstico. La hipertrigliceridemia (> 150 mg/dl) fue observada en 31.5 por ciento (IC95 por ciento 29.3-33.9 por ciento) de la población en estudio. CONCLUSIONES: Los datos de la ENSANUT 2006 confirman que la prevalencia de hipoalfalipoproteinemia y otras formas de dislipidemia es muy alta en los adultos mexicanos.

[Dyslipidemia prevalence and its relationship with insulin resistance in a population of apparently healthy subjects]. / Prevalencia de dislipidemias en una población de sujetos en apariencia sanos y su relación con la resistencia a la insulina.

OBJECTIVE: Evaluate dyslipidemia prevalence and its association with insulin resistance in a cohort of apparently healthy subjects. MATERIAL AND METHODS: A cross-sectional study was conducted with 1,179 donors ages 35 to 65 years. The sample population was comprised of 71% men, with an average age of 44 +/- 7. Clinical records, anthropometric data, lipid profile, fasting glycaemia, and insulin levels were obtained. RESULTS: Prevalence of hypertriglyceridemia was 57.3%, C-HDL under normal limits was 52.4%, and hypercholesterolemia was 48.7%. In addition, 36.8% of the obese individuals (as measured by waist perimeter) had hypertriglyceridemia/hypoalphalipoproteinemia, 35.2% had mixed dyslipidemia, and 33.4% had hypertriglyceridemia. Patterns of dyslipidemia were higher in subjects diagnosed with insulin resistance. CONCLUSIONS: Insulin resistance associated with hypertriglyceridemia and hypoalphalipoproteinemia was common among our studied population. However, a significant proportion of cases of apparent healthy individuals continue to go undiagnosed.

Prevalencia de dislipidemias en una población de sujetos en apariencia sanos y su relación con la resistencia a la insulina / Dyslipidemia prevalence and its relationship with insulin resistance on a population of apparently healthy subjects

OBJETIVO: Conocer la prevalencia de las dislipidemias en una población de sujetos en apariencia sanos y su relación con la resistencia a la insulina (RI). MATERIAL Y MÉTODOS: Este es un estudio transversal que incluyó a 1 179 individuos, donadores voluntarios de 35 a 65 años. Se obtuvo el historial clínico y se realizaron examen físico, determinación del perfil de lípidos, glucemia y niveles de insulina en ayuno. RESULTADOS: La edad promedio fue de 44 ± 7 años; 836 (71 por ciento) correspondían al género masculino. La prevalencia de hipertrigliceridemia fue de 57.3 por ciento, hipoalfalipoproteinemia de 52.4 por ciento e hipercolesterolemia de 48.7 por ciento. De los sujetos con obesidad (perímetro de cintura aumentado), 36.8 por ciento tenía hipertrigliceridemia/hipoalfalipoproteinemia, 35.2 por ciento dislipidemia mixta y 33.4 por ciento hipertrigliceridemia. La prevalencia de los patrones de dislipidemias fue mayor en sujetos con RI. CONCLUSIONES: La hipertrigliceridemia e hipoalfalipoproteinemia, vinculadas con RI, son comunes en la población mexicana; empero, una considerable proporción de casos carece de diagnóstico.

OBJECTIVE: Evaluate dyslipidemia prevalence and its association with insulin resistance in a cohort of apparently healthy subjects. MATERIAL AND METHODS: A cross-sectional study was conducted with 1 179 donors ages 35 to 65 years. The sample population was comprised of 71 percent men, with an average age of 44 ± 7. Clinical records, anthropometric data, lipid profile, fasting glycaemia, and insulin levels were obtained. RESULTS: Prevalence of hypertriglyceridemia was 57.3 percent, C-HDL under normal limits was 52.4 percent, and hypercholesterolemia was 48.7 percent. In addition, 36.8 percent of the obese individuals (as measured by waist perimeter) had hypertriglyceridemia/hypoalphalipoproteinemia, 35.2 percent had mixed dyslipidemia, and 33.4 percent had hypertriglyceridemia. Patterns of dyslipidemia were higher in subjects diagnosed with insulin resistance. CONCLUSIONS: Insulin resistance associated with hypertriglyceridemia and hypoalphalipoproteinemia was common among our studied population. However, a significant proportion of cases of apparent healthy individuals continue to go undiagnosed.

The ATP-binding cassette transporter A1 R230C variant affects HDL cholesterol levels and BMI in the Mexican population: association with obesity and obesity-related comorbidities.

Although ATP-binding cassette transporter A1 (ABCA1) is well known for its role in cholesterol efflux and HDL formation, it is expressed in various tissues, where it may have different functions. Because hypoalphalipoproteinemia is highly prevalent in Mexico, we screened the ABCA1 coding sequence in Mexican individuals with low and high HDL cholesterol levels to seek functional variants. A highly frequent nonsynonymous variant (R230C) was identified in low-HDL cholesterol but not in high-HDL cholesterol individuals (P = 0.00006). We thus assessed its frequency in the Mexican-Mestizo general population, seeking possible associations with several metabolic traits. R230C was screened in 429 Mexican Mestizos using Taqman assays, and it was found in 20.1% of these individuals. The variant was significantly associated not only with decreased HDL cholesterol and apolipoprotein A-I levels but also with obesity (odds ratio 2.527, P = 0.005), the metabolic syndrome (1.893, P = 0.0007), and type 2 diabetes (4.527, P = 0.003). All of these associations remained significant after adjusting for admixture (P = 0.011, P = 0.001, and P = 0.006, respectively). This is the first study reporting the association of an ABCA1 variant with obesity and obesity-related comorbidities as being epidemiologically relevant in the Mexican population.