title: A new mutation in the RP1L1 gene in a patient with occult macular dystrophy associated with a depolarizing pattern of focal macular electroretinograms.
abstract: OBJECTIVE
  To determine whether a mutation in the RP1-like protein 1 (RP1L1) gene is present in a Japanese patient with sporadic occult macular dystrophy (OMD) and to examine the characteristics of focal macular electroretinograms (ERGs) of the patient with genetically identified OMD.
  
  
  METHODS
  An individual with OMD underwent detailed ophthalmic clinical evaluations including focal macular ERGs. Mutation screening of all coding regions and flanking intron sequences of the RP1L1 gene were performed with DNA sequencing analysis in this case with OMD.
  
  
  RESULTS
  A new RP1L1 mutation (c.3596 C>G in exon 4) was identified. The variant c.3596 C>G in exon 4 resulted in the substitution of cysteine for serine at amino acid position 1199. The serine at position 1199 is well conserved among the RP1L1 family in other species. Four out of five computational assessment tools predicted that this mutation is damaging to the protein function. This mutation was not present in 294 control alleles. The waveform of focal macular ERGs recorded from the patient with OMD had a depolarizing pattern, simulating the ERG waveforms observed after the hyperpolarizing bipolar cell activity is blocked.
  
  
  CONCLUSIONS
  We have demonstrated in a Japanese patient the possibility that sporadic OMD may also be caused by an RP1L1 mutation. The waveform of focal macular ERGs elicited from the OMD patient with the RP1L1 mutation showed a depolarizing pattern. This characteristic is the same as reported for the focal macular ERGs of OMD.
authors.affiliation: Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan.
authors.forename: Takenori
authors.initials: T
authors.lastname: Kabuto
authors.forename: Hisatomo
authors.initials: H
authors.lastname: Takahashi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Goto-Fukuura
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Igarashi
authors.forename: Masakazu
authors.initials: M
authors.lastname: Akahori
authors.forename: Shuhei
authors.initials: S
authors.lastname: Kameya
authors.forename: Takeshi
authors.initials: T
authors.lastname: Iwata
authors.forename: Atsushi
authors.initials: A
authors.lastname: Mizota
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Yamaki
authors.forename: Yozo
authors.initials: Y
authors.lastname: Miyake
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D019943:Amino Acid Substitution; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D016022:Case-Control Studies; D004596:Electroretinography; D005091:Exons; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D006801:Humans; D007438:Introns; D008268:Macular Degeneration / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D012160:Retina / Q000378:metabolism* / Q000503:physiopathology; D017422:Sequence Analysis, DNA
chemical_list: D005136:Eye Proteins; C474032:RP1L1 protein, human