Farmacogenómica de los anticoagulantes orales: la importancia de establecer algoritmos de dosificación en población chilena

There is an important interindividual variability in dose requirement for coumarinic anticoagulants, which could be explained by genetic and non-genetic factors. Among hereditary factors, there are gene polymorphisms that code the therapeutic target and the main enzyme responsible for their metabolism. However, there are other candidate genes that could modulate dose requirements. The is a paucity of pharmacogenomic platforms to determine dose requirements of coumarinics in the Chilean population. Therefore, algorithms considering different variables to adjust individual dosages are required. Herein, we analyze the available evidence about factors that can modify the effects of vitamin K antagonists and that should be incorporated to dosing algorithms.

Association of polymorphisms within the Renin-Angiotensin System with metabolic syndrome in a cohort of Chilean subjects

ABSTRACT Objective Metabolic syndrome (MetS) is associated with hypertension, obesity and dyslipidemia. Thus, genetic variants related with these conditions may modulate its development. We evaluated the effect of polymorphisms in the renin-angiotensin system (RAS) on metabolic syndrome risk in a cohort of Chilean subjects. Subjects and methods A total of 152 subjects, 83 with MetS (51.2 ± 9.6 years) and 69 without MetS (49.5 ± 9.3 years) of both genders were included, according to the ATP III update criteria. The rs4340 Insertion/Deletion (I/D), rs699 (T>C) and rs5186 (A>C) of the ACE, AGT and AGTR1 genes, respectively, were genotyped. Results After adjusting for age and gender, we observed the DD genotype of rs4340 associated with MetS (p = 0.02). Specifically, the DD genotype was associated with MetS risk in women (OR = 4.62, 95%CI, 1.41 – 15.04; p < 0.01). In males, the AA genotype for rs5186 variant was associated with an increased risk for developing MetS when compared with women carrying the same genotype (OR = 3.2; 95%CI, 1.03 – 9.89; p = 0.04). In subjects without MetS, DD genotype was associated with increased waist circumference (p = 0.023) while subjects with MetS carrying the rs5186 TT genotype showed higher levels of HDL-cholesterol (p = 0.031). Conclusion The present study contributes data highlighting the role for RAS polymorphisms in predisposing to metabolic syndrome in Chilean subjects.

Asociación de variantes funcionales en genes del metabolismo de la homocisteína con riesgo de trombosis venosa profunda e hiperhomocisteinemia en individuos del Sur de Chile / Association of functional variants in homocysteine metabolism genes, deep venous thrombosis risk and hyperhomocysteinemia in Southern Chilean subjects

Introducción: La Trombosis Venosa Profunda (TVP) es un importante problema de salud en la sociedad moderna. Evidencia reciente sugiere una asociación entre variantes funcionales en genes del metabolismo de la homocisteína con TVP. Sin embargo, los resultados entre poblaciones son contradictorios. En este trabajo, evaluamos la potencial asociación entre la presencia de polimorfismos en genes del metabolismo de la homocis-teína y susceptibilidad a TVP e hiperhomocisteinemia en sujetos chilenos. Métodos: Un total de 231 individuos, 77 pacientes con diagnóstico de TVP y 154 controles fueron incluidos en el estudio. Polimorfismos en los genes Metilenotetrahi-drofolato reductasa (MTHFR) y Cistationina p-sintetasa fueron genotipificados por PCR-RFLP Las concentraciones de homocisteína basal fueron cuantificadas mediante Inmunoensayo de Fluorescencia Polarizada. Resultados: La distribución genotípica y frecuencias alélicas del polimorfismo MTHFR C677T fue significativamente diferente entre pacientes y controles (p<0.01). Odds Ratio para TVP asociada al genotipo homocigoto fue 3.68 (I.C. 95 por ciento: 1.628-8.337, p<0.01). Por el contrario, la distribución genotípica de la variante CBS 844ins68 fue similar en ambos grupos (OR=1.82, I.C. 95 por ciento: 0.636-5.234, p=0.257). Además, los portadores del genotipo homocigoto MTHFR 677TT presentaron niveles más elevados de homocisteína plasmática. Conclusiones: El polimorfismo MTHFR C677T constituye un biomarcador de riesgo de TVP en población chilena, y se relaciona a mayores niveles de homo-cisteína en sujetos homocigotos. Los resultados sugieren que la detección molecular de esta variante debería ser incluida en el estudio básico de Trombofilia en nuestra población.

Background: Deep Venous Thrombosis (DVT) is an important health problem in modern society. Recent evidence suggests an association between functional variants in homocysteine metabolism genes and DVT. However, findings in different populations have been contradictory. In this work, we evaluated the potential association between the presence of polymorphisms in homocysteine metabolism genes, DVT susceptibility and hyperhomocysteinemia in Chilean subjects. Methods: A total of 231 individuals, 77 patients with diagnosis of DVT and 154 controls were included in this study. Common variants in Metylenete-trahydrofolate reductase (MTHFR) and Cistationine p-synthetase (CBS) genes were genotyped by PCR-RFLP. Basal homocysteine was quantified by Fluorescence Polarization Immunoassay. Results: Genotype distribution and allelic frequencies of MTHFR C677T polymorphism were significantly different between patients and controls. Odds Ratio for DVT associated to homozygous status was 3.68 (95 percent C.I., 1.628-8.337, p<0.01). On the other hand, the genotype distribution of the CBS 844ins68 variant was similar in both groups (OR 1.82, 95 percent C.I.: 0.636-5.234, p=0.257). In addition, the individuals carrying the MTHFR 677TT homozygous genotype exhibited higher levels of homocysteine. Conclusion: The MTHFR C677T polymorphism constituted a molecular biomarker of DVT in Chilean population, and related to higher levels of homocysteine in homozygote subjects. The results suggest that the molecular detection of this polymorphism should be included in the basic screening for thrombophilia in our population.

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.

Variante protrombótica C677T del gen metilenotetrahidrofolato reductasa es un biomarcador molecular de fallas de implantación en mujeres chilenas sometidas a protocolos de reproducción asistida / Prothrombotic variant C677T at the methylenetetrahydrofolate reductase gene is a molecular biomarker of implantation failure in chilean women undergoing assisted reproductive protocols

Las fallas de implantación son consideradas una importante causa de infertilidad en mujeres sometidas a protocolos de Fecundación Asistida. Evidencia reciente sugiere que la presencia de variantes protrombóticas está asociada a diversos defectos obstétricos y falla reproductiva. Sin embargo, los resultados en diversas poblaciones son contradictorios. De acuerdo a esta evidencia, se evaluó la potencial asociación entre variantes protrombóticas y fallas de implantación en mujeres chilenas incluidas en protocolos de fecundación asistida. Un total de 180 mujeres, 80 pacientes sometidas a protocolos de reproducción asistida y 100 controles fueron incluidas en este estudio. La genotipificación molecular de variantes protrombóticas en genes candidatos fue realizada por PCR-RFLP. Observamos una paciente heterocigota para la variante F5 G1691A y ausencia total del polimorfismo F2 G20210A en pacientes y controles. La distribución genotípica y la distribución relativa de alelos del polimorfismo MTHFR C677T fueron significativamente diferentes entre pacientes y controles. Odds Ratio para fallas de implantación asociadas al genotipo homocigoto fue 2,78 (95 por ciento IC 1,147 - 6,755; p= 0,0199). En resumen, nuestros resultados sugieren que la variante MTHFR C677T constituye un biomarcador molecular de susceptibilidad a fallas de implantación población chilena.

Implantation failures are considered an important cause of infertility in women undergoing assisted reproductive protocols. Recent evidence suggests that the presence of prothrombotic variants is associated with obstetric defects and reproductive failure. However, results between several populations are contradictory. According this evidence, we evaluated the potential association between prothrombotic variants and implantation failure susceptibility in Chilean women undergoing Assisted Reproductive protocols. 180 women, 80 patients undergoing assisted reproductive protocols and 100 controls were included in this study. Molecular genotyping of prothrombotic variants in candidate genes was realized by PCR-RFLP. We observed one patient heterozygote for factor V G1691A variant, and total absence to prothrombin G20210A polymorphism in patients and controls. Genotype distribution and allelic frequencies of MTHFR C677T polymorphism were significantly different between patients and controls (p<0.05). Odss Ratio for implantation failure associated to homozygote genotype was 2.78 (95 percent IC 1.147 ¡ 6.755; p= 0.0199). In summary, our data suggest that the MTHFR C677T polymorphism constituted a molecular biomarker of implantation failure susceptibility in Chilean population.

A Common 34C>G Variant at the Peroxisome Proliferator-Activated Receptor gamma Gene in Chilean Women with Polycystic Ovary Syndrome and Controls / Polimorfismo 34C>G del Gen del Receptor Activado por Proliferadores Peroxisomales-gamma en Mujeres Chilenas con Síndrome de Ovario Poliquístico y Controles

The 34C>G (Prol2Ala) polymorphic variant of the peroxisome proliferator-activated receptor-γ2 (PPAR-γ2) gene has been associated with polycystic ovary syndrome (PCOS). However, the results between populations are contradictory. Thus, in the present study was investigated the possible association between 34C>G polymorphism at the PPAR-γ2 gene and PCOS in Chilean women. A total of 50 unrelated women (29.1 + 8.1 years) with diagnosis of PCOS and 75 healthy controls (29.3+ 9.3 years) were included in this study. Serum lipids, glucose and uric acid levels were determined by enzymatic-colorimetric methods. The 34C>G variant in the PPAR-γ2 gene was analyzed by PCR-RFLP. Women with PCOS exhibited a higher levels of glucose, total cholesterol, triglycerides, LDL-C and uric acid, and lower HDL-C levels than controls (p <0.05). The frequency of the 34G alíele was 9% in PCOS patients and 12% in control women (p = 0.589). The odds ratio for PCOS associated with 34G alíele was 0.73 (95% CI = 0.31 - 1.69) confirming the absence of association. We conclude that the 34C>G polymorphism of the PPAR-γ2 gene is not related to PCOS in Chilean women.

El polimorfismo 34C>G del gen del receptor activado por proliferadores peroxisomales-γ2 (PPAR-72) ha sido relacionado con el síndrome de ovario poliquístico (SOP). Sin embargo, los resultados obtenidos entre poblaciones son contradictorios. En el presente estudio se investigó la posible asociación entre el polimorfismo 34C>G del gen PPAR-γ2 y SOP, en mujeres chilenas. Fueron analizadas 50 mujeres no relacionadas con diagnóstico de SOP (29.1 ±8.1 años) y 75 mujeres controles (29.3 ±9.3 años). Se evaluaron las concentraciones séricas de lípidos, glucosa y ácido úrico mediante métodos enzimáticos-colorimétricos. La genotipificación de la variante 34C>G del gen PPAR-γ2 fue realizada mediante la técnica de PCR-RFLP. Los datos muestran que las mujeres con SOP presentan elevados niveles de glucosa, colesterol total, triglicéridos, LDL-C y ácido úrico; y bajos niveles de HDL-C al ser comparadas con las mujeres controles (p<0.05). La frecuencia del alelo mutado 34G fue 9% en las mujeres con SOP y 12% en las mujeres controles (p=0.589). La odds ratio para PCOS asociada al alelo 34G fue 0.73 (I.C.95% = 0.31 - 1.69) confirmando la ausencia de asociación. En conclusión, nuestros datos sugieren que el polimorfismo 34C>G del gen PPAR-γ2 no está relacionado a SOP, en mujeres chilenas.