Clinical, Anthropometric and Biochemical Characteristics of Patients with or without Genetically Confirmed Familial Hypercholesterolemia / Características Clínicas, Antropométricas e Bioquímicas de Pacientes com ou sem Diagnóstico Confirmado de Hipercolesterolemia Familiar

Abstract Background: Familial hypercholesterolemia (FH) is a common autosomal dominant disorder, characterized by a high level of low-density lipoprotein cholesterol (LDL-C) and a high risk of premature cardiovascular disease. Objective: To evaluate clinical and anthropometric characteristics of patients with the familiar hypercholesterolemia (FH) phenotype, with or without genetic confirmation of FH. Methods: Forty-five patients with LDL-C > 190 mg/dl were genotyped for six FH-related genes: LDLR, APOB, PCSK9, LDLRAP1, LIPA and APOE. Patients who tested positive for any of these mutations were considered to have genetically confirmed FH. The FH phenotype was classified according to the Dutch Lipid Clinic Network criteria. Results: Comparing patients with genetically confirmed FH to those without it, the former had a higher clinical score for FH, more often had xanthelasma and had higher LDL-C and apo B levels. There were significant correlations between LDL-C and the clinical point score for FH (R = 0.382, p = 0.037) and between LDL-C and body fat (R = 0.461, p = 0.01). However, patients with mutations did not have any correlation between LDL-C and other variables, while for those without a mutation, there was a correlation between LDL-C and the clinical point score. Conclusions: LDL-C correlated with the clinical point score and with body fat, both in the overall patient population and in patients without the genetic confirmation of FH. In those with genetically confirmed FH, there were no correlations between LDL-C and other clinical or biochemical variables in patients.

Resumo Fundamentos: A hipercolesterolemia familiar (HF) é uma doença autossômica dominante, caracterizada por altos níveis plasmáticos do colesterol da lipoproteína de baixa densidade (LDL-C) e pelo alto risco de desenvolvimento prematuro de doenças cardiovasculares. Objetivo: Avaliar características clínicas e antropométricas de pacientes com fenótipo para hipercolesterolemia familiar (HF), com ou sem diagnóstico genético de HF. Métodos: Quarenta e cinco pacientes com LDL-C > 190 mg/dL foram genotipados para seis genes relacionados com a HF: LDLR, APOB, PCSK9, LDLRAP1, LIPA e APOE. Pacientes que apresentaram resultado positivo para qualquer uma das mutações foram diagnosticados com HF por confirmação genética. O fenótipo para HF foi classificado pelo critério da Dutch Lipid Clinic Network. Resultados: Comparando os pacientes com a HF geneticamente confirmada com aqueles sem a confirmação, os primeiros apresentaram maior pontuação do escore para HF, uma maior frequência de xantelasma e maiores níveis de LDL-C e apo B. Houve correlações significativas entre o LDL-C e a pontuação do escore para HF (R = 0,382, p = 0,037) e entre LDL-C e gordura corporal (R = 0,461, p = 0,01). Os pacientes com mutações, no entanto, não apresentaram qualquer correlação entre o LDL-C e outras variáveis, enquanto aqueles sem mutação apresentaram correlação entre o LDL-C e a pontuação do escore. Conclusão: O LDL-C correlacionou-se com a pontuação do escore e com a gordura corporal, tanto na população total de pacientes quanto nos pacientes sem a confirmação genética de HF. Naqueles com HF geneticamente confirmada, não houve correlação entre o LDL-C e outras variáveis clínicas ou bioquímicas dos pacientes.

Relación entre factores genéticos y medioambientales y la hipercolesterolemia en niños / Relationship between genetic and environmental factors and hypercholesterolemia in children

Introducción. La hipercolesterolemia infantil aumentó en las últimas décadas. Conocer los factores ambientales y genéticos que influyen sobre ella permitiría establecer pautas de pesquisa más adecuadas. Objetivos. Analizar si existe asociación entre factores genéticos y ambientales y la hipercolesterolemia en niños. Evaluar las cualidades predictivas de las variables que muestren asociación con la hipercolesterolemia. Material y métodos. Estudio observacional, analítico, transversal. Población: alumnos de todas las escuelas de Jovita. Edad: > 6 y < 12 años. Se midió la colesterolemia total. Mediante encuestas a los padres, se evaluó la historia clínica familiar (HCF) y el nivel socioeconómico (NSE). Se registró el peso y la talla para determinar el estado nutricional. Por medio de una encuesta al niño, se identificó el nivel de actividad física y los hábitos dietéticos. Se evaluó la asociación mediante el cálculo de OR (p < 0,05). Se efectuaron pruebas diagnósticas sobre las variables para predecir hipercolesterolemia. Resultados. Se incluyeron382 alumnos. La media de colesterolemia fue de 168 mg/dl. Un 13,4% presentaron hipercolesterolemia. El sedentarismo fue del 22,8%, y la obesidad, del 10,5%. La HCF positiva, el NSE alto-mediano y la obesidad se asociaron con hipercolesterolemia (OR 2,10; 2,10 y 2,05, respectivamente). No se encontró asociación entre actividad física e ingesta de grasas y colesterol e hipercolesterolemia. La HCF positiva y el NSE alto-mediano mostraron sensibilidad (75% y 88%) para predecir hipercolesterolemia. La hipercolesterolemia de ambos padres en relación con la hipercolesterolemia del hijo mostró un OR 9,59, sensibilidad de 73%, especificidad de 71%, valor predictivo positivo de 57% y negativo de 83%. Conclusiones. La HCF positiva, el NSE alto-mediano y la obesidad se asociaron con hipercolesterolemia en el niño. La hipercolesterolemia en ambos padres presentó una asociación con la de los niños y mostró un buen potencial como factor predictor y criterio de pesquisa.

Introduction. Pediatric hypercholesterolemia has increased over the past decades. Knowing the environmental and genetic factors that have an impact on it would allow establishing more adequate screening guidelines. Objectives. To determine if there is an association between genetic and environmental factors and hypercholesterolemia in children. To assess the predictive qualities of outcome measures associated with hypercholesterolemia. Material and methods. Observational, analytical, cross-sectional study. Population: students from all schools located in Jovita. Age: > 6 and < 12 years old. The total cholesterol level was measured. A survey was administered to parents to assess their family medical history (FMH) and socioeconomic level (SEL). Weight and height were recorded to establish nutritional status. A survey was administered to children to identify their level of physical activity and their eating habits. The association was assessed by estimating the OR value (p < 0.05). Diagnostic tests were done to establish outcome measures that predict hypercholesterolemia. Results. Three hundred and eighty-two students were included. Their mean cholesterol level was 168 mg/dL, and 13.4% had hypercholesterolemia. A sedentary lifestyle was observed in 22.8%, and obesity, in 10.5%. A positive FMH, a high/ middle SEL, and obesity were associated with hypercholesterolemia (OR: 2.10, 2.10 and 2.05, respectively). No association was found between physical activity and fat/cholesterol intake and hypercholesterolemia. A positive FMH and a high/middle SEL were sensitive enough (75% and 88%) to predict hypercholesterolemia. The presence of hypercholesterolemia inboth parents in relation to hypercholesterolemia in their child showed an OR of 9.59, a sensitivity of 73%, a specificity of 71%, a positive predictive value of 57%, and a negative predictive value of 83%. Conclusions. A positive FMH, a high/ middle SEL, and obesity were associated with hypercholesterolemia in children. The presence of hypercholesterolemia in both parents was associated with hypercholesterolemia in their child and showed itself to be a great potential predictor and screening criterion.

Effect of garlic extract on some serum biochemical parameters and expression of npc1l1, abca1, abcg5 and abcg8 genes in the intestine of hypercholesterolemic mice.

Some compounds in the garlic inhibit cholesterol synthesis, resulting in lowering of serum cholesterol and triglycerides and increase in HDL level. However, the mechanism of this specific effect is not fully understood. In the small intestine, ATP-binding cassette transporters G5, G8 and A1 (ABCG5, ABCG8 and ABCA1), as well as Niemann-Pick C1 like 1 (NPC1L1) protein have important roles in cholesterol metabolism. In this study, we evaluated the beneficial effect of aqueous extract of garlic on lipid profile and also expression of npc1l1, abca1, abcg5 and abcg8 genes in the intestine of N-Marry mice fed a high cholesterol diet as a possible mechanism of garlic effect. Twenty-four mice were randomly divided into three groups: Group 1: hypercholesterolmic (received chow + 2% cholesterol + 0.5% cholic acid); Group 2: garlic (received chow + 4% (w/w) garlic extract + 2% cholesterol + 0.5% cholic acid); and Group 3: received chow only. After one month, mice were anesthetized and blood was collected from their heart. The jejunum was removed, washed with PBS and entrocytes were scraped and used for the experiments. Serum lipids were measured enzymatically and expression of mRNA levels for the above-mentioned proteins was determined by semi-quantitative RT-PCR. Garlic extract significantly reduced serum lipids (p<0.05), compared with the hypercholesterolemic group. Expression of the intestinal npc1l1 was significantly decreased (p<0.01) in the garlic group, compared with the chow group, while abcg5 (p<0.01), abcg8 (p<0.01) and abca1 (p<0.05) expressions were significantly increased. In conclusion, this study reveals a possible mechanism for the beneficial effects of the garlic in lowering serum lipids by decreasing the intestinal lipid absorption and increasing excretion of cholesterol back into the intestinal lumen.

Mutation in the PCSK9 gene in Omani Arab subjects with autosomal dominant hypercholesterolemia and its effect on PCSK9 protein structure

Proprotein convertase subtilisin/kexin type [PCSK9] is a crucial protein in LDL cholesterol [LDL-C] metabolism by virtue of its pivotal role in the degradation of the LDL receptor. Mutations in the PCSK9 gene have previously been found to segregate with autosomal dominant familial hypercholesterolemia [ADFH]. In this study, DNA sequencing of the 12 exons of the PCSK9 gene has been performed for two patients with a clinical diagnosis of familial hypercholesterolemia where mutation in the LDL-receptor gene hasn't been excluded. One missense mutation was detected in the exon 9 PCSK9 gene in the two ADFH patients. The patients were found to be heterozygote for Ile474Val [SNP rs562556] Using an array of in silico tools, we have investigated the effect of the above mutation on different structural levels of the PCSK9 protein Although, the mutation has already been reported in the literature for other populations, to the best of our knowledge this is the first report of a mutation in the PCSK9 gene from the Arab population, including the Omani population

Effect of five single nucleotide polymorphisms of ABCG5 and ABCG8 genes on eLipid-lowering response / Efecto de cinco polimorfismos de los genes ABCG5 y ABCG8 sobre la respuesta hipolipemiante a ezetimiba

In this study we evaluated the possible association between five single nucleotide polymorphisms in ABCG5 (rs6720173) and ABCG8 (rs11887534, rs4148211, rs4148217 and rs6544718) genes and ezetimibe response in Chilean hypercholesterolemic subjects. A total of 60 non-related hypercholesterolemic subjects, aged 18 to 65 years old were included in this study. These subjects were treated with ezetimibe (10mg/day) during one month. The ABCG5 and ABCG8 genotypes were assessed by PCR-RFLP. The genotype distribution of the ABCG5/ABCG8 polymorphisms was in Hardy-Weinberg equilibrium. Our results showed that the investigated polymorphisms were not associated with the response to ezetimibe. Nevertheless, the T allele of rs6544718 polymorphism was related to higher baseline levels of LDL-cholesterol (p<0.001). In addition, the G allele for the rs4148211 polymorphism was associated with greater baseline concentrations of triglycerides (P=0.019). This allele was also associated with lower concentrations of HDL-cholesterol (P=0.027), after ezetimibe treatment. Our results suggest that the studied polymorphisms do not affect the therapeutic response to ezetimibe in the evaluated subjects.

En este estudio se evaluó la posible asociación entre cinco polimorfismos de nucleótido único en los genes ABCG5 (rs6720173) y ABCG8 (rs11887534, rs4148211, rs4148217 y rs6544718) y la respuesta a ezetimiba en pacientes hipercolesterolémicos chilenos. Un total de 60 individuos hipercolesterolemicos, no relacionados, con edades entre 18 y 65 años fueron incluidos. Estos sujetos fueron tratados con ezetimiba (10mg/día) durante un mes. Los genotipos de ABCG5 y ABCG8 fueron evaluados por PCR-RFLP. La distribución de genotipos de los polimorfismos de ABCG5/ABCG8 se encontraba en equilibrio de Hardy-Weinberg. Nuestros resultados mostraron que los polimorfismos estudiados no se asociaron con la respuesta a la ezetimiba. Sin embargo, el alelo T del polimorfismo rs6544718 fue relacionado con niveles basales elevados de LDL-colesterol (p <0,001). Además, el alelo G para el polimorfismo rs4148211 se asoció con una mayor concentración basal de triglicéridos (p = 0,019). Este alelo también se asoció con concentraciones más bajas de HDL-colesterol (p = 0,027), después del tratamiento con ezetimiba. Nuestros resultados sugieren que los polimorfismos estudiados no afectan a la respuesta terapéutica a la ezetimiba en los sujetos evaluados.

Frequency of common variants in genes involved in lipid-lowering response to statins in Chilean subjects with hypercholesterolemia / Frecuencia de polimorfismos en genes relacionados a la respuesta terapéutica a estatinas en individuos chilenos con hipercolesterolemia

Interindividual differences in activity and expression of the metabolizing enzymes cytochrome P450 (CYP) 3A4 and 3A5 and the multidrug efflux pump P-glycoprotein (P-gp, encoded by ABCB1 gene) contribute considerably to lipid-lowering efficacy of statin treatment in subjects with hypercholesterolemia. Variability in the activity of CYP3A4, CYP3A5 and P-gp could be considered to result from genetic polymorphisms encoding their genes. However, the available data indicate that the frequencies of ABCB1, CYP3A4 and CYP3A5 gene polymorphisms differ significantly across populations. Thus, the aim of the present study was to determine the allelic frequency of three common variants of these genes in Chilean individuals with primary hypercholesterolemia (HC) and controls. A total of 135 unrelated patients (44 +/- 7 years old) with diagnosis of hypercholesterolemia (Total cholesterol 240 mg/dL) and 120 normolipidemic healthy controls (40 +/- 10 years old; total cholesterol 200 mg/dL) were included in this study. The 3435C>T (MDR1), -290A>G (CYP3A4) and 6986A>G (CYP3A5) gene polymorphisms were analyzed by PCR-RFLP. The genotype distribution for 3435C>T variant of ABCB1 in HC patients (CC: 49 percent, CT: 37 percent, TT: 14 percent) and controls (CC: 41 percent, CT: 48 percent, TT: 11 percent) was comparable (P=0.186). Similarly, the genotype distribution for -290A>G polymorphism of CYP3A4 in HC subjects (AA: 73 percent, AG: 27 percent, GG: 0 percent) and controls (AA: 71 percent, AG: 29 percent, GG: 0 percent) was equivalent (P = 0.863). Finally, the genotype distribution for 6986A>G variant of CYP3A5 in HC individuals (AA: 4 percent, AG: 41 percent, GG: 55 percent) and controls (AA: 4 percent, AG: 47 percent, GG: 49 percent) was similar (P=0.594). The allelic frequencies of 3435C>T (ABCB1), -290A>G (CYP3A4) and 6986A>G (CYP3A5) polymorphisms are similar between Chilean HC patients and controls, and comparable to frequencies found in Asian populations.

Polimorfismos de los genes CYP3A4, CYP3A5 y ABCB1 se han asociado a variaciones en la respuesta a fármacos hipolipemiantes, como las estatinas; principales medicamentos utilizados para disminuir los niveles plasmáticos de colesterol (CT). Sin embargo, la frecuencia de estas variantes genéticas puede variar entre las poblaciones. Así, el objetivo de este trabajo fue evaluar la frecuencia de tres polimorfismos de los genes CYP3A4, CYP3A5 y ABCB1, relacionados previamente a la respuesta a estatinas, en individuos chilenos hipercolesterolémicos (HC) y controles. Se analizaron 135 sujetos con diagnóstico de hipercolesterolemia primaria (CT 240 mg/dL) y 120 controles (CT 200 mg/dL) pertenecientes a la Región de La Araucanía (Chile). La genotipificación de las variantes genéticas se efectuó mediante la técnica de reacción en cadena de la polimerasa seguido de restricción enzimática (PCR-RFLP). La distribución de genotipos para la variante 3435C>T del gen ABCB1 en los individuos HC (CC: 49 por ciento, CT: 37 por ciento, TT: 14 por ciento) y controles (CC: 41 por ciento, CT: 48 por ciento, TT: 11 por ciento) fue semejante (P = 0,186). De forma similar, la distribución de genotipos para el polimorfismo -290A>G del gen CYP3A4 en los pacientes HC (AA: 73 por ciento, AG: 27 por ciento, GG: 0 por ciento) y controles (AA: 71 por ciento, AG: 29 por ciento, GG: 0 por ciento) fue equivalente (P = 0,863). Del mismo modo, la distribución de genotipos para la variante 6986A>G del gen CYP3A5 en el grupo HC (AA: 4 por ciento, AG: 41 por ciento, GG: 55 por ciento) y grupo control (AA: 4 por ciento, AG: 47 por ciento, GG: 49 por ciento) fue similar (P = 0,594). En resumen, nuestro estudio demuestra que las frecuencias de los polimorfismos 3435C>T (ABCB1), -290A>G (CYP3A4) y 6986A>G (CYP3A5) no difieren entre individuos HC y controles, y son comparables a las frecuencias encontradas en poblaciones asiáticas. Su efecto sobre el tratamiento con estatinas en la población chilena debe ser...

Hipercolesterolemias graves en pediatría: Presentación de dos casos / Severe hypercholesterolemia in children: Presentation of two cases and update of the literature

La hipercolesterolemia familiar es uno de los trastornos genéticos más comunes y aporta información sustancial sobre papel etiológico que el colesterol LDL tiene para el desarrollo de la ateroesclerosis. Se presentan dos pacientes con hipercolesterolemia grave. Se remarca la importancia del diagnóstico y tratamiento temprano para evitar o demorar la enfermedad ateromatosa y la enfermedad coronaria precoz.

Familial hypercholesterolemia is one of the most common genetic disorders and it provides the best evidence on the etiologic role of LDL-colesterol for arteroesclerosis development. Two patients with severe hypercholesterolemia had been presented. Importance of early diagnosis and treatment has been stated to avoid or delay atherosclerosis and coronary heart disease.

Efecto de variantes de los genes ABCB1 y CYP3A4 sobre la respuesta terapéutica a atorvastatina en individuos chilenos hipercolesterolémicos / The effect of a variant of gene ABCB1 and CYP3A4A on Atorvastatin therapeutic answer in chilean hypercholesterolemic individuals

Introducción: El tratamiento farmacológico con estatinas es eficaz en el control de la hipercolesterolemia Sin embargo, su respuesta terapéutica presenta gran variabilidad interindividual. Factores como edad, género y etnia han sido relacionados a esta variabilidad. Además, estudios recientes demuestran que polimorfismos genéticos también pueden influir sobre la respuesta terapéutica a estos hipolipemiantes. Así, el objetivo del presente trabajo fue investigar el efecto de tres polimorfismos de los genes ABCB1 (3435C>T y 2677G>A>T) y CYP3A4 (-290A>G) sobre la respuesta al tratamiento con atorvastatina en individuos chilenos hipercolesterolémicos. Métodos: Fueron evaluados 94 individuos hipercolesterolémicos adultos, 35 hombres y 59 mujeres, tratados con atorvastatina (10mg/día) durante 4 semanas. Se realizó medición de los niveles séricos de colesterol total, triglicéridos, HDL-c y LDL-c, antes y después del tratamiento. La genotipificación de los polimorfismos se realizó mediante PCR-RFLP Resultados: Después de 4 semanas de tratamiento, se observaron reducciones significativas en los niveles de colesterol total (275 +/- 18 vs. 235 +/- 22 mg/dL, p<0.001), LDL-c (183 +/- 16 vs. 146 +/- 24 mg/dL, p<0.001) y triglicéridos (225 +/- 48 vs. 172 +/- 51 mg/dL, p<0.001). Además, se observó un aumento en las concentraciones de HDL-c (47 +/- 10 vs. 55 ± 7, p<0.001). La distribución de genotipos para el polimorfismo 3435C>T (ABCB1) fue: CC=47.9 por ciento, CT= 41.5 por ciento y TT=10.6 por ciento; para el polimorfismo trialélico 2677G>A>T (ABCB1): AA=1.1 por ciento, GA=14.9 por ciento, GT=28.7 por ciento, TA=9.6 por ciento, TT=8.5 por ciento y GG=37.2 por ciento y para -290A>G (CYP3A4) fue: AA= 77.7 por ciento, AG= 22.3 por ciento y GG=0.0 por ciento. Los portadores del alelo G de la variante -290A>G (CYP3A4) presentaron mayor reducción de colesterol total (p=0.001) y LDL-C (p<0.001), y un mayor aumento de HDL-c (p<0.001). No se observaron diferencias significativas para...

Background: : statins are effective in the control of hypercholesterolemia. However, the therapeutic response to these drugs presents a great inter-individual variability. Factors such as age, gender and ethnicity have been associated to this variability. Recent studies show that polymorphisms can influence the lipid-lowe-ring response to statins. The aim of the present study was to investigate the effect of three polymorphisms 3435C>T (ABCB1), 2677G>A/T (ABCB1) and -290 A>G (CYP3A4) gene on the response to atorvastatin treatment in Chilean hypercholesterolemic individuals. Methods: 94 hypercholesterolemic individuals, were treated with atorvastatin, 10mg/day for 4 weeks. We determined serum levels of total cholesterol, HDL-c, LDL-c and triglycerides, before and after treatment. The polymorphisms were analyzed by PCR-RFLP. Results: Significant reductions were observed in total cholesterol (275 +/- 18 vs. 235 +/- 22 mg/dL, p<0.001), LDL-c (183 +/- 16 vs. 146 +/- 24 mg/dL, p<0.001) and triglycerides levels (225 +/- 48 vs. 172 +/- 51 mg/dL, polymorphisms on the therapeutic hypercholesterolemic individuals p<0.001). In addition, an increase in the HDL-C levels was observed (47 +/- 10 vs. 55 ± 7, p<0.001). The genotype distribution for 3535C>T variant of ABCB1 gene was: CC=47.9 percent, CT=41.5 percent and TT=10.6 percent. The genotype distribution for 2677G>A/T polymorphism (ABCB1) was AA=1.1 percent, GA=14.9 percent, GT=28.7 percent, TA=9.6 percent, TT=8.5 percent and GG=37.2 percent. The genotype distribution for -290A>G variant of CYP3A4 gene was: AA=77.7 percent. AG=22.3 percent and GG=0.0 percent. Subjects carrying the G allele for the -290 A>G variant of the CYP3A4 gene, exhibited a greater reduction in total cholesterol (p=0.001) and LDL-C levels (p<0.001). No differences were observed for the other polymorphisms studied. Conclusion: This study suggests that the therapeutic response to atorvastatin (10mg/day during 4 weeks) is influenced by the -290 A>G...

Asociación de niveles de lípidos y haplogrupos Amerindios de DNA mitocondrial en individuos chilenos hipercolesterolémicos tratados con atorvastatina / Association of serum lipid levels and mitochondrial DNA Amerindian haplogroups in hypercholesterolemic subjects receiving atorvastatin

Resumen: Introducción: La respuesta terapéutica a estatuías se ve influenciada por factores como la edad, género y etnicidad. Con respecto a esto, el background genético de la población chilena es predominantemente Amerindio, definido por la presencia de haplogrupos Amerindios A, B, C y D de DNA mitocondrial (mtDNA). Así, el objetivo del estudio fue evaluar la potencial asociación entre la presencia de haplogrupos Amerindios de mtDNA y niveles de lípidos en individuos chilenos hipercolesterolémicos tratados con Atorvastatina. Métodos: Un total de 42 individuos en dos centros de salud del sur de Chile fueron incluidos en el estudio. En el grupo de pacientes se evaluó la presencia de haplogrupos Amerindios de mtDNA por PCR-RFLP, además de la cuantificación de Colesterol Total, Triglicéridos, Colesterol-HDL y Colesterol-LDL, antes y después del tratamiento con Atorvastatina (10 mg/día). Resultados: El 88.1 por ciento de los sujetos presentó algún haplogrupo Amerindio, no observándose diferencias en los niveles de lípidos pre- tratamiento de acuerdo al haplogrupo. Interesantemente, individuos de haplogrupo B presentaron niveles mayores de Colesterol Total (B: 254 +/- 30 mg/dl v/s C: 213 +/- 48 mg/dl, D: 230 +/- 50 mg/dl; p= 0.0319) y Colesterol-LDL (B: 157 +/- 34 mg/dl v/s C: 118 +/- 45 mg/dl, D: 135 +/- 42 mg/dl; p=0.0344) post-tratamiento. Conclusiones: El haplogrupo B se asocia a niveles mayores de lípidos post-tratamiento en pacientes tratados con Atorvastatina. Estos hallazgos sugieren por primera vez, que la presencia de haplogrupo B de mtDNA determinaría una menor respuesta al tratamiento con Atorvastatina en individuos chilenos con background genético amerindio.

Background: Therapeutic response to statins is influenced by age, gender and ethnicity. The genetic background of the Chilean population is predominantly Amerindian, defined by the presence of mitochondrial DNA (mtDNA) Amerindian haplogroups A, B, C and D Amerindian haplogroups and serum lipid levéis in hypercholesterolemic Chilean subjects receiving atorvastatin Methods: 42 subjects from southern Chile were included. The presence of mtDNA Amerindian haplogroups was evaluated by PCR-RFLP; in addition, total cholesterol, triglycerides, HDL-cholesterol and LDL-cholesterol were measured before and after treatment with atorvastatin 10 mg/day. Aim: to evaluate a possible association of mtDNA. Ameridian haplogroups and serum lipid levels in hypercholesterolemic Chilean subjects receiving atorvastatin. Result: 88.1 percent of subjects exhibited some Amerindian haplogroup. No relation of lipid levels with haplogroups was observed before treatment. Interestingly, haplogroup B individuals had higher levels of total cholesterol compared to other haplogroups after treatment (haplogroup B : 254 +/- 30 mg/dl; C : 213 +/- 48 mg/dl; D : 230 +/- 50 mg/dl, p=0.0319). Corresponding levels for LDL-cholesterol after treatment in the three groups were 157 +/- 34,118 +/-45 and 135 +/-42 mg/ di, respectively, p=0.0344. Conclusion: Compared to other haplogroups, haplogroup B is associated to higher levels of lipids after treatment with atorvastatin. For the first time, these findings suggest that the presence of mtDNA haplogroup B determines a dimished response to atorvastatin in Chilean subjets with an Amerindian genetic background.

Frecuencia de la variante 23968A>G del gen PCSK9 en individuos chilenos con enfermedad coronaria confirmada por angiografía y controles / Frequency of 23, 968A>G polymorphism at the PCSK9 gene in Chilean subjects with coronary artery disease confirmed by angiography and controls

Introducción: Variaciones comunes en el gen PCSK9 han sido asociadas a elevadas concentraciones de colesterol plasmático. Entre ellas, el polimorfismo 23968A>G ha sido relacionado con hipercolesterolemia poligénica en individuos europeos y japoneses. Objetivos: Determinar la frecuencia de la variante 23968A>G del gen PCSK9 en pacientes con enfermedad arterial coronaria y controles, y evaluar su posible contribución al desarrollo de esta patología en individuos chilenos. Métodos: Se efectuó genotipificación de la variante 23968A>G del gen PCSK9 a 218 individuos no relacionados de la Región de La Araucanía: 110 con enfermedad coronaria confirmada por angiografía (estenosis >70 por ciento) y 108 sujetos controles, mediante la técnica de reacción en cadena de la polimerasa seguida de restricción enzimática (PCR-RFLP). Resultados: La distribución de genotipos para el polimorfismo 23968A>G del gen PCSK9 en los pacientes con enfermedad coronaria (AA: 95.5 por ciento, AG: 4.5 por ciento, GG: 0 por ciento) y controles (AA: 95.4 por ciento, AG: 4.6 por ciento, GG: 0 por ciento) fue similar (p= 0.769). La frecuencia del alelo mutado G fue también semejante entre casos y controles (0.0227 vs. 0.0231, p=0.771). La odds ratio (OR) relacionada al alelo mutado G fue 0.98 (I.C. 95 por ciento: 0.28 - 3.44) confirmando la ausencia de asociación. Conclusiones: El polimorfismo 23968A>G del gen PCSK9 no contribuye para el desarrollo de enfermedad arterial coronaria en la población estudiada.

Background: Common variants of the PCSK9 gene are associated to elevation of plasma cholesterol levels. Among them, the 23968A>G variant has been related to polygenic hipercholesterolemia in European and in Japanese subjects. Aim: to determine the frequency of the 23968A>G variant of the PCSK9 gene in patients with coronary artery disease and controls and to estimate its significance in the development of CAD in Chilean subjects. Methods: Genotypes of the 23968A>G variant of the PCSK9 gene were determined in 218 unrelated subjectsin the Region de La Araucania. One- hundred ten had angiography proven significant coronary artery disease(>70 percent stenosis) and 108 were controls. PCR followed by enzymatic restriction was used. Results: The genotype distribution for 23,968A>G variant in CAD patients (AA: 95.5 percent, AG: 4.5 percent, GG: 0 percent) and controls (AA: 95.4 percent, AG: 4.6 percent, GG: 0 percent) was similar (p=0.769). The relative frequency of mutated 23,968G allele in CAD and controls was not significantly different (0.0227 vs. 0.0231, p=0.771). Moreover, the odds ratio (OR) shown that the G allele was not associated with CAD (OR: 0.98; 95 percent C.I. = 0.28 - 3.44, P = NS). Conclusion: The 23968A>G polymorphism of the PCSK9 gene is not related to the presence of CAD in this population.

Hipercolesterolemia familiar heterocigota: diagnóstico molecular y terapia combinada. Caso clínico / Molecular diagnosis and combined lipid lowering therapy of heterozygous familial hypercholesterolemia: Report of one case

Heterozygous familial hypercholesterolemia affects one every 400 individuals, is caused by mutations in the LDL receptor gene and is associated with premature coronary artery disease. Nowadays, LDL cholesterol can be efficiently reduced with the new therapies to reduce blood lipids. We report a female patient who consulted in 1975, when she was 46 years old, for severe hypercholesterolemia. In 2003, a sample of leukocyte DNA was obtained and the uncommon 1705 + 1G >A mutation of the LDL receptor gene was detected. No mutations in the apolipoprotein B gene were found. The patient was treated successfully with simvastatin 80 mg/day and ezetimibe 10 mg/day and LDL cholesterol levels were reduced below 200 mg/dl.

High baseline serum total and LDL cholesterol levels are associated with MDR1 haplotypes in Brazilian hypercholesterolemic individuals of European descent

The MDR1 gene encodes the P-glycoprotein, an efflux transporter with broad substrate specificity. P-glycoprotein has raised great interest in pharmacogenetics because it transports a variety of structurally divergent drugs, including lipid-lowering drugs. The synonymous single-nucleotide polymorphism C3435T and the nonsynonymous single-nucleotide polymorphism G2677T/A in MDR1 have been indicated as potential determinants of variability in drug disposition and efficacy. In order to evaluate the effect of G2677T/A and C3435T MDR1 polymorphisms on serum levels of lipids before and after atorvastatin administration, 69 unrelated hypercholesterolemic individuals from São Paulo city, Brazil, were selected and treated with 10 mg atorvastatin orally once daily for four weeks. MDR1 polymorphisms were analyzed by PCR-RFLP. C3435T and G2677T polymorphisms were found to be linked. The allelic frequencies for C3435T polymorphism were 0.536 and 0.464 for the 3435C and 3435T alleles, respectively, while for G2677T/A polymorphism allele frequencies were 0.580 for the 2677G allele, 0.384 for the 2677T allele and 0.036 for the 2677A allele. There was no significant relation between atorvastatin response and MDR1 polymorphisms (repeated measures ANOVA; P > 0.05). However, haplotype analysis revealed an association between T/T carriers and higher basal serum total (TC) and LDL cholesterol levels (TC: 303 ± 56, LDL-C: 216 ± 57 mg/dl, respectively) compared with non-T/T carriers (TC: 278 ± 28, LDL-C: 189 ± 24 mg/dl; repeated measures ANOVA/Tukey test; P < 0.05). These data indicate that MDR1 polymorphism may have an important contribution to the control of basal serum cholesterol levels in Brazilian hypercholesterolemic individuals of European descent.

Homozygous DNA variants in exon 9 of the LDL receptor gene in a Thai patient with primary hypercholesterolemia phenotype.

Mutation in low density lipoprotein (LDL) receptor gene causes an inherited primary hypercholesterolemia namely familial hypercholesterolemia (FH). In this study, 46 Thai patients with primary hypercholesterolemia were screened for mutations in exon 9 of the LDL receptor gene by polymerase chain reaction-restriction fragment length polymorphism (PCR - RFLP). The analysed fragment was 224 bp in length. According to the published cDNA sequence, exon 9 of the LDL receptor gene contains several hypermutable CpG dinucleotides. Three of these sites are Hpa II recognition sites. PCR product of exon 9 obtained from amplification of wild-type DNA sample would yield four fragments after Hpa II digestion. The expected sizes of these restriction fragments were 15, 30, 40 and 139 bp. All normocholesterolemic subjects (n = 33) showed normal RFLP. However, in one patient (72 year old female), abnormal RFLP from Hpa II digestion of the amplified exon 9 was observed, i.e., a fragment of 70 bp and another one smaller than 139 bp. Such RFLP reflects that exon 9 of both alleles of the LDL receptor gene in this patient lost one and gained one Hpa II site. It is interesting that this patient, eventhough harbouring two mutations on both alleles of the LDL receptor gene (presumably homozygous genotype of FH), apparently revealed lipid levels of heterozygous phenotype of FH without symptoms of coronary artery disease. It has yet to be proved whether these genetic variations are disease-related mutations or presumably common DNA polymorphisms.

Inexpensive, rapid and convenient PCR-minigel SSCP protocol for polymorphisms and mutations analyses of LDL receptor gene.

Hypercholesterolemia has been recognized as a major risk factor of atherosclerosis and coronary artery disease. The elevation in plasma low density lipoprotein (LDL) cholesterol is frequently due to genetic alteration at the genetic locus specifying the LDL receptors, leading to defective catabolism of LDL. In order to facilitate the molecular diagnosis of LDL receptor disorder, single strand conformation polymorphism (SSCP) analysis of polymerase chain reaction (PCR) amplified genomic DNA fragments has become a simple and sensitive screening method for identification of DNA polymorphisms and mutations in LDL receptor gene prior to DNA sequencing. In addition, SSCP patterns can be detected by silver staining to avoid hazardous radioactive material or other costly nonradioactive detection techniques. However, the original SSCP protocol is generally large-formatted, which is both time and reagents consuming as well as cumbersome. Minigel SSCP protocols have thus been devised but they involve, although commercially available, costly precast gels. We describe here a nonradioactive PCR-minigel SSCP protocol which is sensitive, inexpensive, rapid, reproducible and manually convenient. The results in this study demonstrate that minigel-SSCP (gel size: 10 cm x 7.3 cm x 0.075 cm) can detect conformation polymorphisms in PCR-fragments with a comparative sensitivity to large gel SSCP (gel size: 30 cm x 40 cm x 0.04 cm) as exemplified by the SSCP analyses of exon 13 of the LDL receptor gene. For minigel SSCP, the reagents for gel components and silver staining are reduced approximately 9 times and 10 times, respectively. For electrophoresis, electrical power is also reduced 10 times. This improved technique can become routinely used for molecular diagnosis of LDL receptor defect as well as for other genetic disorders.

Mutation analysis of exon 9 of the LDL receptor gene in Thai subjects with primary hypercholesterolemia.

The low density lipoprotein (LDL) receptor plays an important role in cholesterol homeostasis. A mutation in this gene causes an autosomal codominant disorder, namely familial hypercholesterolemia (FH). In this study, single strand conformation polymorphism (SSCP) analysis was used to screen for mutations in exon 9 of the LDL receptor gene in a group of 45 Thai patients (11 males and 34 females) with primary hypercholesterolemia. The peptide encoded by exon 9 belongs to the epidermal growth factor (EGF) precursor homology domain which is highly conserved in the LDL receptor protein. An abnormal SSCP pattern was observed in one female patient. The same screening strategy was also used to screen DNA samples from 33 normolipidemic subjects. All of these samples showed normal SSCP pattern. By direct DNA sequencing, the underlying mutation in the DNA with abnormal SSCP pattern was identified. The index subject was heterozygous for a T to C transition at nucleotide 1235. This transition would cause a nonconservative substitution of a nonpolar side chain amino acid "methionine" at codon 391, with an uncharged polar side chain amino acid "threonine", note M391T. From multiple amino acid sequence alignment in six species, the amino acid at codon 391 and the others nearby are completely conserved. Such nonconservative substitution of an amino acid residue in a highly conserved region could consequently result in a functional and/or structural defect in the receptor protein. In conclusion, we propose that M391T is likely to be the cause of hypercholesterolemia in this index subject.

Screening for mutations in exon 4 of the LDL receptor gene in Thai subjects with primary hypercholesterolemia: detection of a novel mutation D151Y by PCR-CFLP.

A mutation in low density lipoprotein (LDL) receptor gene causes an autosomal codominant disorder namely familial hypercholesterolemia (FH). Mutations in the LDL receptor gene are very heterogeneous at the DNA levels, occurring in all 18 exons of the gene. However, exon 4 has been found to be the hot spot for mutational events. In this study DNA from 45 Thai subjects with primary hypercholesterolemia was screened for mutations in the hot spot exon 4. The DNA samples were amplified by Polymerase Chain Reaction (PCR) and screened for mutation by Cleavase Fragment Length Polymorphism (CFLP) technique. Identification of mutation was performed by direct sequencing of PCR product. From this screening, one female patient was found to be heterozygous for a novel mutation which was due to a G to T transversion at nucleotide 514. This transversion would change the species-conserved amino acid at codon 151 from charged R group aspatic (GAC) to uncharged R group tyrosine (TAC), termed D151Y. From the same screening strategy, we found that this mutation was absent in 33 healthy normolipidemic subjects. In this index subject, Arg 3500 Gln mutation in apo B-100 gene, causing hypercholesterolemia namely familial defective apo B-100 (FDB), was not found. Therefore, hypercholesterolemia in this index subject was possibly caused by the D151Y mutation in the LDL receptor gene.

Genotipagem da apolipoproteína E em indivíduos hipercolesterolêmicos e em diabéticos / Apo E genotyping in hypercholesterolemic and diabetic individuals

Com a crescente necessidade de otimizaçäo de técnicas moleculares para fins de diagnóstico precoce, estabeleceu-se uma metodologia para obtençäo de DNA genômico de células sangüíneas, tornando-a mais acessível aos laboratórios clínicos. Obteve-se ótimo rendimento de DNA (60,9 ñ 1,6 µg/ml), de alta qualidade e pureza. Essa metodologia foi entäo aplicada para obtençäo de material genético para o estudo de genotipagem de apolipoproteína E (apo E) em indivíduos hipercolesterolêmicos (HIPERCOL), diabéticos insulino-dependente (IDDM) e näo-insulino-dependente (NIDDM), assim como avaliou-se a influência do polimorfismo genético da apo E na hipercolesterolemia pós-menopausa...