Segregation of a totally skewed pattern of X chromosome inactivation in four familial cases of Rett syndrome without MECP2 mutation: implications for the disease
Abstract : Background—Rett syndrome is a neurodevelopmental disorder a Vecting only girls; 99.5% of Rett syndrome cases are sporadic, although several familial cases have been reported. Mutations in the MECP2 gene were identified in approximately 70-80% of sporadic Rett syndrome cases.
Methods—We have screened the MECP2 gene coding region for mutations in five familial cases of Rett syndrome and studied the patterns of X chromosome inactivation (XCI) in each girl.
Results—We found a mutation in MECP2 in only one family. In the four families without mutation in MECP2, we found that (1) all mothers exhibit a totally skewed pattern of XCI; (2) six out of eight a Vected girls also have a totally skewed pattern of XCI; and (3) it is the paternally inherited X chromosome which is active in the patients with a skewed pattern of XCI. Given that the skewing of XCI is inherited in our families, we genotyped the whole X chromosome using 32 polymorphic markers and we show that a locus potentially responsible for the skewed XCI in these families could be located on the short arm of the X chromosome.
Conclusion—These data led us to propose a model for familial Rett syndrome transmission in which two traits are inherited, an X linked locus abnormally escaping X chromosome inactivation and the presence of a skewed XCI in carrier women.
https://hal-amu.archives-ouvertes.fr/hal-01593090 Contributor : Lionel SpinelliConnect in order to contact the contributor Submitted on : Thursday, December 6, 2018 - 10:12:04 AM Last modification on : Friday, March 4, 2022 - 9:36:03 AM Long-term archiving on: : Thursday, March 7, 2019 - 1:04:50 PM
Laurent Villard, Nicolas Lévy, Fengqing Xiang, Arlette Kpebe, Véronique Labelle, et al.. Segregation of a totally skewed pattern of X chromosome inactivation in four familial cases of Rett syndrome without MECP2 mutation: implications for the disease. Journal of Medical Genetics, BMJ Publishing Group, 2001, 38 (7), pp.435-442. ⟨10.1136/jmg.38.7.435⟩. ⟨hal-01593090⟩