title: Identification of a novel mutation in the CDHR1 gene in a family with recessive retinal degeneration.
abstract: OBJECTIVE
  To describe the clinical phenotype and identify the molecular basis of disease in a consanguineous family of Palestinian origin with autosomal recessive retinal degeneration.
  
  
  METHODS
  Eight family members were evaluated with visual acuity and perimetry tests, color fundus photographs, full-field electroretinography, and optical coherence tomography. Cone photoreceptors surrounding the fovea were imaged in 2 members, using adaptive optics scanning laser ophthalmoscopy. Exome was captured using probes and sequenced. Readings were mapped to reference hg19. Variant calls and annotations were performed, using published protocols. Confirmation of variants and segregation analysis was performed using dideoxy sequencing.
  
  
  RESULTS
  Analysis detected 24 037 single-nucleotide variants in one affected family member, of which 3622 were rare and potentially damaging to encoded proteins. Further analysis revealed a novel homozygous nonsense change, c.1381 C>T, p.Gln461X in exon 13 of the CDHR1 gene, which segregated with retinal degeneration in this family. Affected members had night blindness beginning during adolescence with progressive visual acuity and field loss and unmeasurable electroretinographic responses, as well as macular outer retinal loss, although residual cones with increased cone spacing were observed in the youngest individual.
  
  
  CONCLUSIONS
  Exome analysis revealed a novel CDHR1 nonsense mutation segregating with progressive retinal degeneration causing severe central vision loss by the fourth decade of life. High-resolution retinal imaging revealed outer retinal changes suggesting that CDHR1 is important for normal photoreceptor structure and survival.
  
  
  CONCLUSIONS
  Exome sequencing is a powerful technique that may identify causative genetic variants in families with autosomal recessive retinal degeneration.
authors.affiliation: Shiley Eye Center, University of California San Diego, Jacobs Retina Center, 9415 Campus Point Dr, Room 206, San Diego, CA 92093, USA.
authors.forename: Jacque L
authors.initials: JL
authors.lastname: Duncan
authors.forename: Austin
authors.initials: A
authors.lastname: Roorda
authors.forename: Mili
authors.initials: M
authors.lastname: Navani
authors.forename: Sangeetha
authors.initials: S
authors.lastname: Vishweswaraiah
authors.forename: Reema
authors.initials: R
authors.lastname: Syed
authors.forename: Shiri
authors.initials: S
authors.lastname: Soudry
authors.forename: Kavitha
authors.initials: K
authors.lastname: Ratnam
authors.forename: Harini V
authors.initials: HV
authors.lastname: Gudiseva
authors.forename: Pauline
authors.initials: P
authors.lastname: Lee
authors.forename: Terry
authors.initials: T
authors.lastname: Gaasterland
authors.forename: Radha
authors.initials: R
authors.lastname: Ayyagari
mesh_terms: D000328:Adult; D000368:Aged; D000070585:Cadherin Related Proteins; D015820:Cadherins / Q000235:genetics*; D018389:Codon, Nonsense; D055253:Color Vision / Q000502:physiology; D003241:Consanguinity; D004252:DNA Mutational Analysis; D004596:Electroretinography; D059472:Exome / Q000235:genetics; D005260:Female; D005808:Genes, Recessive / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009887:Ophthalmoscopy; D010375:Pedigree; D010641:Phenotype; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012029:Refraction, Ocular / Q000502:physiology; D012162:Retinal Degeneration / Q000235:genetics* / Q000503:physiopathology; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult
chemical_list: C442481:CDHR1 protein, human; D000070585:Cadherin Related Proteins; D015820:Cadherins; D018389:Codon, Nonsense; D009419:Nerve Tissue Proteins