title: Frequency of GJB2 and del(GJB6-D13S1830) mutations among an Ecuadorian mestizo population.
abstract: OBJECTIVE
  The frequency of GJB2 mutations and of the del(GJB6-D13S1830) mutation has not been established among the Ecuadorian mestizo population diagnosed with autosomal recessive non-syndromic hearing loss. A genetic analysis was therefore designed in order to do so.
  
  
  METHODS
  The sample population included 111 subjects of which 26 were autosomal recessive non-syndromic hearing loss probands. Posterior to PCR amplification, sequencing analysis of exon 2 was used for mutational detection of the GJB2 gene; a multiplex PCR method was used for detection of the del(GJB6-D13S1830) mutation. The ratio of subjects with a certain state of the mutation (heterozygous/homozygous) is expressed as a percentage and significant differences between probands and controls were calculated using Fisher's exact test; P<0.05 was considered significant.
  
  
  RESULTS
  A total of 104 mutations belonging to 8 allelic variations were identified. The most common being the V27I (58.9%); however, as this variation is a non-pathogenic polymorphism, Q7X, with a total of 19 mutated alleles, was the most frequent mutation (18.3%). The V27I polymorphism was the only variation distributed homogenously among probands and controls (P=0.351). Based on physical analyses of multiple patients we confirm that Q7X causes a non-syndromic form of hearing loss and propose that it is a possible predominant mutation in the Ecuadorian population.
  
  
  CONCLUSIONS
  This is the first study of its kind among the Ecuadorian population and a preliminary step in establishing GJB2 and del(GJB6-D13S1830) mutational frequencies in this population; it is also the first to report of such a high frequency of the Q7X mutation. The data presented here brings Ecuador a step closer to providing more efficient treatment for a broader number of patients; additionally, it contributes to a better understanding of the relationship between autosomal recessive non-syndromic hearing loss and mutations on the GJB2 gene.
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Medicina, Universidad de las Américas, Quito, Ecuador. Electronic address: cpazymino@udla.edu.ec.
authors.forename: César
authors.initials: C
authors.lastname: Paz-y-Miño
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Medicina, Universidad de las Américas, Quito, Ecuador.
authors.forename: Doyle
authors.initials: D
authors.lastname: Beaty
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Medicina, Universidad de las Américas, Quito, Ecuador.
authors.forename: Andrés
authors.initials: A
authors.lastname: López-Cortés
authors.affiliation: Dirección Nacional de Articulación de la Red Pública y Complementaria de la Salud Enfermedades Raras, Ministerio de Salud Pública, Quito, Ecuador.
authors.forename: Indira
authors.initials: I
authors.lastname: Proaño
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D004484:Ecuador; D005091:Exons; D005260:Female; D005820:Genetic Testing; D034381:Hearing Loss / Q000208:ethnology / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D055815:Young Adult
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26
keywords: Autosomal recessive non-syndromic hearing loss; Del(GJB6-D13S1830); Ecuadorian mestizo population; GJB2; Genetic heterogeneity; Incomplete penetrance