title: Founder effect and ancestral origin of the spinocerebellar ataxia type 7 (SCA7) mutation in Mexican families.
abstract: Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant disease characterized by progressive cerebellar ataxia and macular degeneration causing progressive blindness. It accounts for 1 to 11.6 % of spinocerebellar ataxias (SCAs) cases worldwide and for 7.4 % of SCA7 cases in Mexico. We identified a cluster of SCA7 families who resided in a circumscribed area of Veracruz and investigated whether the high incidence of the disease in this region was due to a founder effect. A total of 181 individuals from 20 families were studied. Four microsatellite markers and one SNP flanking the ATNX7 gene were genotyped and the ancestral origin and local ancestry analysis of the SCA7 mutation were evaluated. Ninety individuals from 19 families had the SCA7 mutation; all were found to share a common haplotype, suggesting that the mutation in these families originated from a common ancestor. Ancestral origin and local ancestry analysis of SCA7 showed that the chromosomal segment containing the mutation was of European origin. We here present evidence strongly suggesting that the high frequency of SCA7 in Veracruz is due to a founder effect and that the mutation is most likely of European origin with greatest resemblance to the Finnish population.
authors.affiliation: Departamento de Neurogenética, Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez", Insurgentes Sur 3877, Col. La Fama, Tlalpan, Mexico City, 14269, Mexico.
authors.forename: Lizbeth E
authors.initials: LE
authors.lastname: García-Velázquez
authors.forename: Samuel
authors.initials: S
authors.lastname: Canizales-Quinteros
authors.forename: Sandra
authors.initials: S
authors.lastname: Romero-Hidalgo
authors.forename: Adriana
authors.initials: A
authors.lastname: Ochoa-Morales
authors.forename: Leticia
authors.initials: L
authors.lastname: Martínez-Ruano
authors.forename: Carla
authors.initials: C
authors.lastname: Márquez-Luna
authors.forename: Víctor
authors.initials: V
authors.lastname: Acuña-Alonzo
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Villarreal-Molina
authors.forename: M Elisa
authors.initials: ME
authors.lastname: Alonso-Vilatela
authors.forename: Petra
authors.initials: P
authors.lastname: Yescas-Gómez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D000067719:Ataxin-7; D002648:Child; D002675:Child, Preschool; D002874:Chromosome Mapping; D004252:DNA Mutational Analysis; D018450:Disease Progression; D005192:Family Health; D018703:Founder Effect; D005819:Genetic Markers; D005838:Genotype; D005843:Geography; D006239:Haplotypes; D006801:Humans; D008800:Mexico; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D025341:Principal Component Analysis; D020754:Spinocerebellar Ataxias / Q000208:ethnology / Q000235:genetics*; D044465:White People; D055815:Young Adult
chemical_list: C000593829:ATXN7 protein, human; D000067719:Ataxin-7; D005819:Genetic Markers; D009419:Nerve Tissue Proteins