The cytogenetic and molecular study of Fragile X syndrome: A leading cause of Autism

Abstract               Background: Fragile X syndrome is common cause of intellectual disability in the patient of autism. Thorough genetic work up, cytogenetic and molecular, is important to establish the diagnosis to have therapeutic and prognostic approach.

Aim: to conduct the karyotyping to find out the fragile site in the X chromosome and to find the mutation by polymerase chain reaction in the FMR1 gene Material and methods: 21 patients (19 males and 2 females) were included in our study with autistic features and clinical features suggestive of fragile X syndrome such intellectual disability, phenotypic features like protruding and large ears, thin and triangular face, strabismus, club foot etc. Genetic familial history, Karyotyping was in the special medium (Thymine and folate deficient medium) to identify the fragile site in the X chromosome. Later on PCR was carried out to find the mutation in the FMR1 gene. Results: In 3 patients fragile X site was observed in karyotyping and of these two cases of mutation in FMR1 gene was observed. The patient with the autism should be tested for the Fragile X Syndrome and to categorise premutations or full mutation for genetic counselling to family members. Conclusion: Thorough Genetic work up which includes karyotyping and molecular studies for FXS in autistic children has to be carried out to establish the diagnosis.

Key Word: Fragile X syndrome.