ABSTRACT
La discriminación y cuantificación de los componentes ambientales y genéticos en el desarrollo de esclerosis múltiple (EM) no se ha podido realizar. con la finalidad de acercarnos a la discriminación de dichos componentes, hemos analizado casos afectados de EM a partir de la comunidad paisa de Antioquia, Colombia, zona situada en el trópico; para detectar un posible desequilibrio de ligamiento al HLA, locus DQÓ, aspecto que revelaría la importancia del componente genético en el desarrollo de EM. Un análisis de contingencia entre las distribuciones genotípicas del HLA DQÓ de los casos y controles, usando el remuestreo de Monte Carlo para solucionar el problema del tamaño muestral que es inherente a las poblaciones con baja prevalencia de EM, reveló que existen diferencias significativas entre las dos distribuciones. La tendencia alélica observada fue de un incremento de los alelos 1.1., 1.2 y una disminución de los alelos 3 (con un p significativamente < de 0,05) y 4 en la población afectada. Los mismos resultados han sido descritos en otras poblaciones de origen caucasoide no localizadas en el trópico, lo cual puede indicar que este componente genético descrito en la población caucasoide se ha mantenido en la poblaciòn de enfermos con EM originarios de Antioquia y que continúa siendo importante para el desarrollo de la enfermedad
Subject(s)
Multiple Sclerosis/epidemiology , Multiple Sclerosis/genetics , ColombiaABSTRACT
Most Colombian populations stem from the admixture of Caucasians, Amerindians and Negroids. In the world, these two latter ethnical groups show a significantly higher prevalence of epilepsy than the former one. We tested the hypothesis that the high prevalence of idiopathic epilepsy with generalized tonic clonic seizures found in the Antioquian population (Paisas), from Colombia, is due to their possible joint Negroid and Amerindian ethnic components. We have previously demonstrated that inheritance is the principal factor for developing epilepsy in this community. Analyses of racial admixture, heterogeneity between populations, genetic distance, and phyletic relationships were performed among epileptic and non epileptic samples from the Antioquian community. Also Caucasians, Spaniards, Basques, Jews, Chileans, Negroids, Amerindians and Mongoloids were included in the analysis. Four highly polymorphic blood systems were used as genetic markers: RH, MNS, ABO and FY. They were chosen because of their high discriminant power in these ethnic groups. In the population affected with idiopathic epilepsy, the estimated Negroid and Amerindian rates of admixture were low (3 percent and 14 percent, respectively). Although, these degrees of admixture can be explained due to common ancestral origins, the estimated proportion of Amerindian admixture in the epileptic affected population, was significantly higher than the estimated for the Non affected Antioquian population. The latter finding is consistent with the analysis of heterogeneity between populations that discriminated epileptic population from non epileptic Antioquian population (p < 0.05). Epileptic and non epileptic Paisas clustered in topology with Caucasians, very close to Spaniards and Basques and highly distant from Negroids and Amerindians. Thus, far, the origin of the high prevalence of idiopathic epilepsy in the Antioquian (Paisa) population cannot be explained by the hypothetical joint Negroid and Amerindian ethnical admixture, but using additional genetic markers and other methods of racial estimation of admixture it is necessary to corroborate if the Amerindian admixture component is significantly higher in the epileptic population than in the non epileptic Paisa population