title: X chromosome-inactivation patterns in patients with Rett syndrome.
abstract: Rett syndrome (RS) is a complex and severely disabling neurologic disorder, restricted to females. As non-random X inactivation could indicate that the X chromosome has a role in the etiology of the syndrome, we performed molecular analysis based on the differential methylation of the active and inactive X chromosomes with probe M27beta, taking into account the parental origin of the two Xs, in 24 RS girls (including a pair of concordant monozygote twins), 22 mothers, and a control group of 30 normal women. The results showed a significantly (Fisher's exact test) increased frequency of skewed X inactivation in lymphocytes from 15/23 RS compared with 4/22 mothers (P = 0.0031) and 6/30 controls (P = 0.0021). Our results, together with those from the literature, showed that as a group, RS patients are apparently more prone to skewed X inactivation than their mothers and normal controls, and this suggests that the X chromosome is somehow involved in RS etiology.
authors.affiliation: Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, SP, Brazil.
authors.forename: A C
authors.initials: AC
authors.lastname: Krepischi
authors.forename: F
authors.initials: F
authors.lastname: Kok
authors.forename: P G
authors.initials: PG
authors.lastname: Otto
mesh_terms: D019175:DNA Methylation; D004200:Diseases in Twins / Q000235:genetics; D004303:Dosage Compensation, Genetic; D005260:Female; D006801:Humans; D015518:Rett Syndrome / Q000235:genetics*; D014430:Twins, Monozygotic