- Balanced translocations and abnormal phenotypes : what is the relationship ?
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The octogonal figure above shows the different phenotypes that can be caused by the presence of a mutation in the MECP2 gene.
These mutations can be divided into two different groups :
- the "Rett type" mutations are all the mutations that are found in Rett Syndrome girls. These mutations most often affect the known functional domains of the MECP2 protein.
- the "MR type" mutations are all the other mutations, never found in girls affected by Rett Syndrome but that can be identified in patients (males or females) with mild to severe mental retardation.
Like for all X-linked genetic diseases, the mutation carrier women can have a different phenotype depending on their X-chromosome inactivation profile.