Molecular Testing of MECP2 Gene in Rett Syndrome Phenotypes in Indian Girls.

OBJECTIVE: To assess yield of MECP2 gene sequence variations analysis and large deletions in suspected cases of Rett syndrome.

DESIGN: Descriptive study.

SETTING: Tertiary-care medical genetics center.

PATIENTS: Girls with neuroregression, postnatal microcephaly and signs and symptoms suggestive of classical and atypical Rett syndrome were classified into two groups. Group I consisted of girls with Classical and atypical Rett syndrome on basis on the Revised Rett Syndrome diagnostic criteria, 2010. Group II included girls with neuroregression and postnatal microcephaly and other Rett like features but not fulfilling the above criteria.

PROCEDURE: Sanger sequencing of coding regions and large deletional analysis of MECP2 gene.

OUTCOME MEASURES: Identification of mutation in MECP2 gene.

RESULTS: Mutation in MECP2 gene was identified in 74% (14/19) in group I and none (0/17) in group II. The mutation detection rate was 93% (13/14) in group I classical Rett syndrome girls (2 with large deletions identified with Multiplex ligation dependent probe amplification) and 20% (1/5) in group I atypical Rett syndrome girls. One novel MECP2 sequence variation was identified in group I classical Rett syndrome.

CONCLUSIONS: The yield of the mutation detection in MECP2 is higher in classical Rett syndrome. In girls with some Rett like features, but not fulfilling revised Rett syndrome diagnostic criteria, mutation testing for MECP2 gene has a low yield.