METHODOLOGY
This study was approved by Institutional Ethical Committee and informed consent was obtained from all participants. Sixty four probands were recruited from various schools, hospitals and speech therapy clinics and clinically diagnosed for stuttering by speech pathologist using Stuttering Severity Instrument 3(SSI-3)34. A structured interview using questionnaire was conducted to elicit demogenetic details (table A1). More details on recruitment of the probands is given in our previous paper6.
Eight milliliters of blood was collected by venipuncture into labelled EDTA coated vacutainers (Beckon and Dickinson Co., USA). Genomic DNA was isolated using Phenol-Chloroform extraction method35.