Low Predisposition to Instability of the Friedreich Ataxia Gene in Cuban Population.
Author(s) and Institute(s) :
1,2Tania Cruz-Mariño,2Yanetza González-Zaldivar, 2José Miguel laffita-Mesa, 2Raúl Aguilera-Rodríguez, 2Luis Velázquez-Pérez.
1Department of Clinical Genetics, Center of Medical Genetics, Holguín, Cuba. 2Center for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.
Presenter :
Dr. Tania Cruz Mariño
Contents of abstract :
Introduction. Cuba is an archipelago in the Caribbean whose population consists of the creole descendants of Spaniards mixed with Sub-Saharan Africans, the Chinese, European Jews and Amerindians to a lesser degree. Recessive ataxias represent 9.16% of inherited ataxias along the country; Friedreich ataxia is considered the commonest condition in this group all over the world. Objectives. To estimate FRDA prevalence in Cuba and to describe the characteristics of both the disease in the affected individuals and the gene in the normal population. Method. In 87 patients affected by recessive or sporadic ataxias molecular studies were carried out through Polymerase Chain Reaction. Results. Only five patients from the west of the island showed expansions at the FRDA locus, the estimated prevalence resulting 1 in 2200000 with a carrier frequency of 1 in 745. The study of 496 normal chromosomes showed there is kurtosis and positive skew, the gene has a normal distribution in the population with 19 alleles ranging from 5 to 31 GAA repeats, being 8 the commonest. The frequencies of short and large normal alleles were 89,11% and 10,89% respectively, premutated or expanded alleles were not identified. Europe, particularly Spain, seems to be a candidate source for the inclusion of FRDA gene in the heterogeneous Cuban genetic background. Conclusions. This data suggest a low predisposition of the repeat to instability and explain the low prevalence of the condition. For the first time, information concerning molecular diagnosis of Cuban families affected by Friedreich ataxia is presented.
Keywords :
ataxia , neurodegeneration , neurogenetics , population genetics , triplet and other repeats