title: Disease manifestations and X inactivation in heterozygous females with Fabry disease.
abstract: OBJECTIVE
  Fabry disease is an X-linked lysosomal storage disorder characterized by an accumulation of neutral glycosphingolipids in multiple organ systems caused by alpha-galactosidase A deficiency due to mutations in the GLA gene. The majority of heterozygous females show the characteristic signs and symptoms of the disease, and some of them are severely affected. The current hypothesis for the occurrence of disease manifestations in females is skewed X inactivation favouring the mutant GLA allele.
  
  
  METHODS
  We analyzed the patterns of X inactivation in the leukocytes of 28 biochemically and genetically characterized symptomatic Fabry disease heterozygotes and their correlation with clinical and biochemical disease expression.
  
  
  RESULTS
  X inactivation patterns in symptomatic females who are heterozygous for Fabry disease did not differ from those of female controls of the same age (p = 0.669). Thirteen (46%) of the 28 females with Fabry disease showed random X inactivation, ten (36%) moderate skewing, and five (18%) highly skewed X inactivation. Segregation analysis was performed in the families of six females who had highly or moderately skewed X inactivation. In four of these females, skewing favoured the wild-type GLA allele and in the other two skewing favoured the mutant allele. Patterns of X inactivation or the extent of skewing were not related to the severity of clinical manifestations or to residual enzyme activity.
  
  
  CONCLUSIONS
  In this study we provide evidence that heterozygous females with Fabry disease show random X inactivation. Our data do not support the hypothesis that the occurrence and severity of disease manifestations in the majority of Fabry heterozygotes are related to skewed X inactivation.
authors.affiliation: Research Centre, Department of Biochemical Genetics and Molecular Biology, Dr von Hauner Children's Hospital, Ludwig-Maximilian University, Munich, Germany.
authors.forename: Esther M
authors.initials: EM
authors.lastname: Maier
authors.forename: Stephanie
authors.initials: S
authors.lastname: Osterrieder
authors.forename: Catharina
authors.initials: C
authors.lastname: Whybra
authors.forename: Markus
authors.initials: M
authors.lastname: Ries
authors.forename: Andreas
authors.initials: A
authors.lastname: Gal
authors.forename: Michael
authors.initials: M
authors.lastname: Beck
authors.forename: Adelbert A
authors.initials: AA
authors.lastname: Roscher
authors.forename: Ania C
authors.initials: AC
authors.lastname: Muntau
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D000795:Fabry Disease / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007962:Leukocytes / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D011944:Receptors, Androgen / Q000235:genetics; D049951:X Chromosome Inactivation / Q000502:physiology; D000519:alpha-Galactosidase / Q000378:metabolism
chemical_list: D011944:Receptors, Androgen; D000519:alpha-Galactosidase