title: Homozygosity mapping in autosomal recessive retinitis pigmentosa families detects novel mutations.
abstract: OBJECTIVE
  Autosomal recessive retinitis pigmentosa (arRP) is a genetically heterogeneous disease resulting in progressive loss of photoreceptors that leads to blindness. To date, 36 genes are known to cause arRP, rendering the molecular diagnosis a challenge. The aim of this study was to use homozygosity mapping to identify the causative mutation in a series of inbred families with arRP.
  
  
  METHODS
  arRP patients underwent standard ophthalmic examination, Goldman perimetry, fundus examination, retinal OCT, autofluorescence measurement, and full-field electroretinogram. Fifteen consanguineous families with arRP excluded for USH2A and EYS were genotyped on 250 K SNP arrays. Homozygous regions were listed, and known genes within these regions were PCR sequenced. Familial segregation and mutation analyzes were performed.
  
  
  RESULTS
  We found ten mutations, seven of which were novel mutations in eight known genes, including RP1, IMPG2, NR2E3, PDE6A, PDE6B, RLBP1, CNGB1, and C2ORF71, in ten out of 15 families. The patients carrying RP1, C2ORF71, and IMPG2 mutations presented with severe RP, while those with PDE6A, PDE6B, and CNGB1 mutations were less severely affected. The five families without mutations in known genes could be a source of identification of novel genes.
  
  
  CONCLUSIONS
  Homozygosity mapping combined with systematic screening of known genes results in a positive molecular diagnosis in 66.7% of families.
authors: INSERM U. 1051, Institute for Neurosciences of Montpellier, Montpellier, France ; Université Montpellier 1, Montpellier, France ; Université Montpellier 2, Montpellier, France.
authors: Béatrice
authors: B
authors: Bocquet
authors: Nour Al Dain
authors: NA
authors: Marzouka
authors: Maxime
authors: M
authors: Hebrard
authors: Gaël
authors: G
authors: Manes
authors: Audrey
authors: A
authors: Sénéchal
authors: Isabelle
authors: I
authors: Meunier
authors: Christian P
authors: CP
authors: Hamel
mesh_terms: D000293:Adolescent; D000328:Adult; D003241:Consanguinity; D005091:Exons; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D005808:Genes, Recessive; D060005:Genotyping Techniques; D006720:Homozygote; D006801:Humans; D007438:Introns; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D011110:Polymorphism, Genetic; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology; D017422:Sequence Analysis, DNA; D012720:Severity of Illness Index
chemical_list: D005136:Eye Proteins