title: Utility of molecular testing for related retinal dystrophies.
abstract: BACKGROUND
  The purpose of this study was to describe our experience with the clinical effects of molecular genetic testing for retinitis pigmentosa (RP) and related retinal dystrophies.
  
  
  METHODS
  Chart review of 303 consecutive patients with retinal dystrophies was done when blood was sent for molecular genetic testing between 1993 and 2001. Phenotype information was retrieved for patients with identified mutations. The yield of positive and clinically useful results was assessed.
  
  
  RESULTS
  Participants comprised 35 patients with Leber congenital amaurosis, 18 with Usher syndrome, and 250 with isolated RP or other retinal dystrophies. Of these 303 participants, 203 (67%) received positive or negative results of molecular testing for an average of 2.7 genes. Positive results were available in 19 patients after an average time interval of 38+/-22 months (median 33 months, range 1-89 months). No results were received for 84 (28%) patients. In 16 (5%) cases, patients received partial results. Only 19 (6%) patients were found to have sequence changes in RHO, RDS, CRB1, or USH2A, 2 of which were thought to be disease-causing. Only 2 sequence changes were previously documented mutations, but several other novel changes were suspected to be disease-causing mutations also.
  
  
  CONCLUSIONS
  Molecular testing was helpful only in the minority of cases, largely because of a lack of availability, as well as the complexity of the molecular genetics of RP. Improvements in funding, infrastructure, and molecular knowledge will be necessary to improve the transformation of molecular genetic testing into a clinically relevant bedside tool.
authors.affiliation: Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, University of Toronto, Ontario, Canada.
authors.forename: Eedy
authors.initials: E
authors.lastname: Mezer
authors.forename: Joanne
authors.initials: J
authors.lastname: Sutherland
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Goei
authors.forename: Elise
authors.initials: E
authors.lastname: Héon
authors.forename: Alex V
authors.initials: AV
authors.lastname: Levin
mesh_terms: D004252:DNA Mutational Analysis; D005136:Eye Proteins / Q000235:genetics; D005819:Genetic Markers; D006801:Humans; D025202:Molecular Diagnostic Techniques; D018807:Polymorphism, Single-Stranded Conformational; D012162:Retinal Degeneration / Q000235:genetics; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D005136:Eye Proteins; D005819:Genetic Markers