title: Genetic Linkage Analysis of 15 DFNB Loci in a Group of Iranian Families with Autosomal Recessive Hearing Loss.
abstract: BACKGROUND
  Hearing loss (HL) is the most frequent sensory birth defect in humans. Autosomal recessive non-syndromic HL (ARNSHL) is the most common type of hereditary HL. It is extremely heterogeneous and over 70 loci (known as DFNB) have been identified. This study was launched to determine the relative contribution of more frequent loci in a cohort of ARNSHL families.
  
  
  METHODS
  Thirty-seven Iranian families including 36 ARNSHL families and 1 family with Pendred syndrome each with ≥ 4 affected individuals, from seven provinces of Iran, were ascertained. DFNB1 contribution was initially studied by DNA sequencing of GJB2 and linkage analysis using the relative STR markers. The excluded families were then subjected to homozygosity mapping for fifteen ARNSHL loci.
  
  
  RESULTS
  Sixteen families were found to be linked to seven different known loci, including DFNB1 (6 families), DFNB4 (3 families +1 family with Pendred syndrome), DFNB63 (2 families), DFNB2 (1 family), DFNB7/11 (1 family), DFNB9 (1 family) and DFNB21 (1 family). DNA sequencing of the corresponding genes is in progress to identify the pathogenic mutations.
  
  
  CONCLUSIONS
  The genetic causes were clarified in 43.2% of the studied families, giving an overview of the causes of ARNSHL in Iran. DFNB4 is ranked second after DFNB1 in the studied cohort. More genetic and epigenetic investigations will have to be done to reveal the causes in the remaining families.
authors.affiliation: Cellular and Molecular Research Center, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran ; Dept. of Medical Genetics, School of Medicine, Jundishapur University of Medical Sciences, Ahvaz, Iran ; Dept. of Medical Genetics, University of Antwerp, 2610, Antwerp, Belgium.
authors.forename: Ma
authors.initials: M
authors.lastname: Tabatabaiefar
authors.forename: F
authors.initials: F
authors.lastname: Alasti
authors.forename: M Montazer
authors.initials: MM
authors.lastname: Zohour
authors.forename: L
authors.initials: L
authors.lastname: Shariati
authors.forename: E
authors.initials: E
authors.lastname: Farrokhi
authors.forename: Dd
authors.initials: D
authors.lastname: Farhud
authors.forename: Gv
authors.initials: G
authors.lastname: Camp
authors.forename: Mr
authors.initials: M
authors.lastname: Noori-Daloii
authors.forename: M Hashemzadeh
authors.initials: MH
authors.lastname: Chaleshtori
keywords: ARNSHL; DFNB loci; Genetic linkage analysis; Iran