title: Homozygous disruption of PDZD7 by reciprocal translocation in a consanguineous family: a new member of the Usher syndrome protein interactome causing congenital hearing impairment.
abstract: A homozygous reciprocal translocation, 46,XY,t(10;11),t(10;11), was detected in a boy with non-syndromic congenital sensorineural hearing impairment. Both parents and their four other children were heterozygous translocation carriers, 46,XX,t(10;11) and 46,XY,t(10;11), respectively. Fluorescence in situ hybridization of region-specific clones to patient chromosomes was used to localize the breakpoints within bacterial artificial chromosome (BAC) RP11-108L7 on chromosome 10q24.3 and within BAC CTD-2527F12 on chromosome 11q23.3. Junction fragments were cloned by vector ligation and sequenced. The chromosome 10 breakpoint was identified within the PDZ domain containing 7 (PDZD7) gene, disrupting the open reading frame of transcript PDZD7-C (without PDZ domain) and the 5'-untranslated region of transcript PDZD7-D (with one PDZ and two prolin-rich domains). The chromosome 11 breakpoint was localized in an intergenic segment. Reverse transcriptase-polymerase chain reaction analysis revealed PDZD7 expression in the human inner ear. A murine Pdzd7 transcript that is most similar in structure to human PDZD7-D is known to be expressed in the adult inner ear and retina. PDZD7 shares sequence homology with the PDZ domain-containing genes, USH1C (harmonin) and DFNB31 (whirlin). Allelic mutations in harmonin and whirlin can cause both Usher syndrome (USH1C and USH2D, respectively) and congenital hearing impairment (DFNB18 and DFNB31, respectively). Protein-protein interaction assays revealed the integration of PDZD7 in the protein network related to the human Usher syndrome. Collectively, our data provide strong evidence that PDZD7 is a new autosomal-recessive deafness-causing gene and also a prime candidate gene for Usher syndrome.
authors.affiliation: Institute of Human Genetics, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Schneider
authors.forename: Tina
authors.initials: T
authors.lastname: Märker
authors.forename: Angelika
authors.initials: A
authors.lastname: Daser
authors.forename: Gabriele
authors.initials: G
authors.lastname: Frey-Mahn
authors.forename: Vera
authors.initials: V
authors.lastname: Beyer
authors.forename: Ruxandra
authors.initials: R
authors.lastname: Farcas
authors.forename: Brigitte
authors.initials: B
authors.lastname: Schneider-Rätzke
authors.forename: Nicolai
authors.initials: N
authors.lastname: Kohlschmidt
authors.forename: Bärbel
authors.initials: B
authors.lastname: Grossmann
authors.forename: Katharina
authors.initials: K
authors.lastname: Bauss
authors.forename: Ulrike
authors.initials: U
authors.lastname: Napiontek
authors.forename: Annerose
authors.initials: A
authors.lastname: Keilmann
authors.forename: Oliver
authors.initials: O
authors.lastname: Bartsch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Zechner
authors.forename: Uwe
authors.initials: U
authors.lastname: Wolfrum
authors.forename: Thomas
authors.initials: T
authors.lastname: Haaf
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002675:Child, Preschool; D002879:Chromosomes, Human, Pair 10 / Q000235:genetics; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics; D003241:Consanguinity; D007758:Ear, Inner / Q000378:metabolism; D005260:Female; D015321:Gene Rearrangement; D034381:Hearing Loss / Q000151:congenital / Q000235:genetics* / Q000378:metabolism; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010375:Pedigree; D014178:Translocation, Genetic; D052245:Usher Syndromes / Q000235:genetics* / Q000378:metabolism