FMR1 gene CGG repeat distribution among the three individual cohorts with intellectual disability, autism, and primary ovarian insufficiency from Tamil Nadu, Southern India
Open Access
- 28 May 2021
- journal article
- research article
- Published by Wiley in Advanced Genetics
- Vol. 2 (2), e10048
- https://doi.org/10.1002/ggn2.10048
Abstract
Fragile X syndrome is the most common genetic cause of intellectual disability (ID) and is also well known to have a role in primary ovarian insufficiency (POI) and fragile X-associated tremor ataxia syndrome (FXTAS) that expresses across generations. The objective was to compare the CGG repeat variants in FMR1 gene among three correlating cohorts of ID, autism and idiopathic POI. Thirty-six patients with ID, 12 with autism spectrum disorder (ASD) and 13 females with idiopathic POI were screened for FMR1 CGG repeat size by fluorescent methylation-specific PCR and GeneScan analysis, irrespective of Hagerman checklist clinical scores. Among 29 males and seven females, 11 FMR1 allelic variants ranging from 21 to >200 CGG repeats were observed. Three (CF2-3, 39-5, 44-2) out of 29 males had full mutation alleles accounting for a 10.34% incidence of FXS among idiopathic ID males. One of them was a mosaic for CGG repeats with both premutation and full mutation alleles. The frequency of fragile X syndrome is high among patients with idiopathic ID; they also had a high score for the clinical check list. A cascade testing that begins with checklist evaluation prior to DNA analysis will be cost-effective for establishing early diagnosis in South India. With the huge disease burden, there is a need for the establishment of more molecular diagnostics and self-help groups for fragile X syndrome.Funding Information
- National Medical Research Council (NMRC/1079/2006)
This publication has 38 references indexed in Scilit:
- Fragile X CGG Repeat Variation in Tamil Nadu, South India: A Comparison of Radioactive and Methylation-Specific Polymerase Chain Reaction in CGG Repeat SizingGenetic Testing and Molecular Biomarkers, 2012
- Intermediate FMR1 alleles and cognitive and/or behavioural phenotypesEuropean Journal of Human Genetics, 2011
- Fragile X carrier screening and FMR1 allele distribution in the Japanese populationBrain & Development, 2010
- Screening for Expanded Alleles of the FMR1 Gene in Blood Spots from Newborn Males in a Spanish PopulationThe Journal of Molecular Diagnostics, 2009
- Fragile X mosaic male full mutation/normal allele detected by PCR/MS-MLPABMJ Case Reports, 2009
- Fragile X Syndrome in Korea: A Case Series and a Review of the LiteratureJournal of Korean Medical Science, 2008
- Simplified Molecular Diagnosis of Fragile X Syndrome by Fluorescent Methylation-Specific PCR and GeneScan AnalysisClinical Chemistry, 2006
- Fragile X screening for FRAXA and FRAXE mutations using PCR based studies: Results of a five year studyIndian Journal of Human Genetics, 2006
- Molecular Screening of FRAXA and FRAXE in Indian Patients with Unexplained Mental RetardationGenetic Testing, 2002
- A general method for the detection of large CAG repeat expansions by fluorescent PCR.Journal of Medical Genetics, 1996