title: Null CYP1B1 genotypes in primary congenital and nondominant juvenile glaucoma.
abstract: OBJECTIVE
  To assess the mutation spectrum, enzymatic activity, and phenotypic features associated with CYP1B1 genotypes in primary congenital glaucoma (PCG) and nondominant juvenile glaucoma (ndJG).
  
  
  METHODS
  CYP1B1 genotyping, segregation analysis, and functional evaluation of mutations in a cohort of patients.
  
  
  METHODS
  A total of 177 probands clinically diagnosed with PCG (161) or ndJG (16).
  
  
  METHODS
  Automatic DNA sequencing of the promoter (-1 to -867) and the 3 CYP1B1 exons. CYP1B1 enzymatic activity was evaluated using an ethoxyresorufin O-deethylation assay in transfected HEK-293T cells.
  
  
  METHODS
  Screening and functional evaluation of CYP1B1 mutations. Glaucoma diagnosis based on slit-lamp examination, measurement of intraocular pressure, gonioscopy, and fundus examination.
  
  
  RESULTS
  Thirty-one different mutations were identified in 56 PCG and 7 ndJG index cases. To the best of our knowledge, 3 of the identified mutations were novel (-337G>T, F123L, and I399_P400del). Approximately 56% of all mutation carriers were compound heterozygotes, 25% were homozygotes, and both groups inherited glaucoma as an autosomal recessive trait. Nineteen percent of carriers were heterozygotes and showed non-Mendelian segregation. In vitro and inferred functional analysis showed that no less than approximately 74% of the recessive genotypes result in null enzymatic activity. We detected variable expressivity in relation to age of onset and a possible case of incomplete penetrance in 3 of 6 families (50%), with more than 1 affected child or more than 1 subject carrying 2 CYP1B1 mutant alleles. Altogether, these data support that PCG is not a simple monogenic disease. In addition, most patients with PCG carrying null or putative null genotypes showed severe bilateral phenotypes featured by early disease onset, frequently at birth. The mean number of trabeculectomies per eye was significantly higher in carriers than in noncarriers.
  
  
  CONCLUSIONS
  This is the largest analysis of CYP1B1 mutations performed in European patients with PCG to date. Our data show that null CYP1B1 genotypes, and therefore complete absence of CYP1B1 activity, frequently lead to severe phenotypes. Our results support that CYP1B1 glaucoma is not a simple monogenic disease and that CYP1B1 activity levels could influence the phenotype.
authors.affiliation: Área de Genética, Facultad de Medicina/Instituto de Investigación en Discapacidades Neurológicas, Universidad de Castilla-La Mancha, Albacete, Spain.
authors.forename: María-Pilar
authors.initials: MP
authors.lastname: López-Garrido
authors.forename: Cristina
authors.initials: C
authors.lastname: Medina-Trillo
authors.forename: Laura
authors.initials: L
authors.lastname: Morales-Fernandez
authors.forename: Julián
authors.initials: J
authors.lastname: Garcia-Feijoo
authors.forename: José-María
authors.initials: JM
authors.lastname: Martínez-de-la-Casa
authors.forename: Maite
authors.initials: M
authors.lastname: García-Antón
authors.forename: Julio
authors.initials: J
authors.lastname: Escribano
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D065633:Cytochrome P-450 CYP1B1; D004247:DNA / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D005901:Glaucoma / Q000151:congenital / Q000201:enzymology / Q000235:genetics*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D055815:Young Adult
chemical_list: D004247:DNA; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1