Studies of X inactivation and isodisomy in twins provide further evidence that the X chromosome is not involved in Rett syndrome.

摘要: Rett syndrome (RS), a progressive encephalopathy with onset in infancy, has been attributed to an X-linked mutation, mainly on the basis of its occurrence almost exclusively females and concordance female MZ twins. The underlying mechanisms proposed are dominant mutation male lethality, uniparental disomy X chromosome, and/or some disturbance process inactivation leading unequal distributions cells expressing maternal or paternal alleles (referred as "nonrandom" "skewed" pattern inactivation). To determine if chromosome is fact involved RS, we studied group affected including three pairs twins, two concordant for RS one uniquely discordant RS. Analysis X-inactivation patterns confirms frequent nonrandom previously observed twins but indicates that this independent 29 reveals not instance disomy, extending observations reported. Therefore, our findings contribute no support hypothesis disorder. Furthermore, phenotype most which known mutations, argues against mutation.