title: Pathological repeat variation at the SCA17/TBP gene in south Indian patients.
abstract: Despite the intense debate around the repeat instability reported on the large group of neurological disorders caused by trinucleotide repeat expansions, little is known about the mutation process underlying alleles in the normal range, diseases range, large normal alleles (LNAs). In this study, we assessed the CAG repeats at SCA17 in 188 clinical SCA patients and 100 individuals without any neurological signs. This highly polymorphic population displayed high variability in the CAG repeats and ranged from 19-38 CAG repeats in patients with mode of 20 and 19-32 CAG repeats in controls with mode of 24. The triplet repeat expansion was not detected in any of the 188 patients, as per the reference pathogenic range (>43 repeats); however, 2.7% of the patients had >33 CAG repeats with a clinical phenotype close to what is expected of SCA 17 patients. The findings of this study implicate a more sophisticated interpretation of SCA17 gene and raise the question about the diagnostic thresh hold between normal and expanded repeats in our population.
authors.affiliation: Department of Genetics, Mahaveer Hospitals and Research Centers, AC Guard-500 004 Hyderabad, India; Department of Genetics, Osmania University, Tarnaka, 500007 Hyderabad, India; Department of Pathology and Microbiology, University of Nebraska and Medical Center, Omaha, NE 68198-7660. USA.
authors.forename: Waseem Gul
authors.initials: WG
authors.lastname: Lone
authors.affiliation: Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 11433, Saudi Arabia.
authors.forename: Imran Ali
authors.initials: IA
authors.lastname: Khan
authors.affiliation: Princess Al-Jawhara Centre of Excellence in Research of Hereditary Disorders, Department of Genetic Medicine, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
authors.forename: Noor Ahmad
authors.initials: NA
authors.lastname: Shaik
authors.affiliation: Department of Neurology, Nizam's Institute of Medical Sciences, Panjagutta, 500082 Hyderabad, India.
authors.forename: Angmuthu Kanikannan
authors.initials: AK
authors.lastname: Meena
authors.affiliation: Department of Genetics, Osmania University, Tarnaka, 500007 Hyderabad, India.
authors.forename: Kaipa Prabhakar
authors.initials: KP
authors.lastname: Rao
authors.affiliation: Department of Neurology, Nizam's Institute of Medical Sciences, Panjagutta, 500082 Hyderabad, India; Department of Genetics and Molecular Medicine, Kamineni Hospitals, LB Nagar-500068, Hyderabad 500 068, India. Electronic address: qhasan2000@yahoo.com.
authors.forename: Qurratulain
authors.initials: Q
authors.lastname: Hasan
mesh_terms: D000328:Adult; D004252:DNA Mutational Analysis; D004569:Electroencephalography; D005260:Female; D005838:Genotype; D006801:Humans; D007194:India; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D020754:Spinocerebellar Ataxias / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology; D035181:TATA-Box Binding Protein / Q000235:genetics*; D014057:Tomography, X-Ray Computed; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*; D055815:Young Adult
chemical_list: D035181:TATA-Box Binding Protein
keywords: CAG repeats; Large normal alleles; Polyglutamine diseases; Reference pathogenic range; SCA17; Trinucleotide repeats