title: DFNB49 is an important cause of non-syndromic deafness in Czech Roma patients but not in the general Czech population.
abstract: Due to endogamy, the Roma have a higher risk for autosomal recessive (AR) disorders. We used homozygosity mapping on single-nucleotide polymorphism chips in one Czech Roma consanguineous family with non-syndromic hearing loss (NSHL). The second largest homozygous region in a deaf patient was mapped to the previously reported DFNB49 region. The MARVELD2 gene was recently reported as a causal gene for NSHL DFNB49. Sequencing of the MARVELD2 gene revealed a previously reported homozygous mutation c.1331+2 T>C (IVS4 + 2 T>C) in the deaf child. Subsequently, the same mutation was found in two more Roma families from an additional 19 unrelated Czech Roma patients with deafness tested for the MARVELD2 gene. To explore the importance of MARVELD2 mutations and DFNB49 for the general Czech and Central European population with early hearing loss we also tested 40 unrelated Czech patients with AR NSHL. No pathogenic mutation in the MARVELD2 gene was found in a group of 40 Czech non-Roma patients. Mutations in the MARVELD2 gene seem to be a significant cause of early NSHL in Czech Roma and this gene should be tested in this group of patients after GJB2.
authors.affiliation: DNA Laboratory, Department of Child Neurology, Charles University 2nd Medical School and University Hospital Motol, Prague, Czech Republic. dana.brozkova@seznam.cz
authors.forename: D
authors.initials: D
authors.lastname: Šafka  Brožková
authors.forename: J
authors.initials: J
authors.lastname: Laštůvková
authors.forename: H
authors.initials: H
authors.lastname: Štěpánková
authors.forename: M
authors.initials: M
authors.lastname: Krůtová
authors.forename: M
authors.initials: M
authors.lastname: Trková
authors.forename: P
authors.initials: P
authors.lastname: Myška
authors.forename: P
authors.initials: P
authors.lastname: Seeman
mesh_terms: D000072259:Connexin 26; D017630:Connexins; D018153:Czech Republic; D004252:DNA Mutational Analysis; D003638:Deafness / Q000235:genetics* / Q000473:pathology; D005006:Ethnicity / Q000235:genetics*; D005808:Genes, Recessive / Q000235:genetics; D006720:Homozygote; D006801:Humans; D062794:MARVEL Domain Containing 2 Protein / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D062794:MARVEL Domain Containing 2 Protein; C516798:MARVELD2 protein, human; D000072259:Connexin 26