Namrata Londhe
Kokilaben Dhirubhai Ambani Hospital, India
Title: Determination of genetic cause in cases of developmental delay- a retrospective study in Indian cohort
Biography
Biography: Namrata Londhe
Abstract
Statement of the Problem: To elucidate the genetic component in patients with developmental delay (DD) through 5 year retrospective data analysis. After the initial workup by the pediatrician, the patients were referred to the department for cytogenetic and molecular testing.
Methodology & Theoretical Orientation: Most detrimental form of developmental delay is global DD which is presented as overall absence of the required milestone in the child including mental, cognitive as well as motor delay. The advent of cytogenetic and molecular biology techniques has been helpful in understanding the genetic etiology of these conditions. DD is affecting 1:150 children. Cases with following indications like Attention Deficit Disorder, Attention Deficit Hyperactivity Disorder, Global DD, Pervasive Developmental Disorder, Pervasive Developmental Disorder-Not Otherwise Specified, Syndromic, Intellectual Disability, Learning Disability, Specific DD, speech delay etc. were all included in the data analysis.
Findings: A total of 199 cases (age ranging from 5 months- 22years) were studied. Cytogenetic analysis was performed on 142 patients and chromosomal abnormalities were observed in 8.5% (12/142) of the cases. FISH assays (For Praderwilli/angelman syndrome, Digeorge, etc) were performed in 59 cases, positive results were obtained in 3.3% (2/59). Molecular analysis (Fragile X analysis, Rett syndrome, etc) was done for 44 subjects. One case 2.4% (1/44) revealed an intermediate phenotype for Fragile-X studies. Chromosomal abnormalities were found in 8.4% (12/142) cases. This observations can be further classified as structural abnormalities in 66.7% (8/12), numerical abnormalities in 25% (3/12) and a combination both abnormalities was seen in 8.3% (1/12) of the cases. Polymorphic variants were found in 4.2% (6/142) of the cases.
Conclusion & Significance: Cytogenetic and molecular tests could successfully elucidate the genetic components implicated in 7.5% of the total cases. As chromosomal analysis can detect the anomalies up to 5MB resolution, advanced techniques like Microarray studies would be more helpful in detecting the cryptic subtle rearrangements in unsolved cases
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Recent Publications:
- John B. Moeschler. Comprehensive Evaluation of the Child With Intellectual Disability or Global Developmental Delays. Pediatrics 2014;134:e903–e918.
- PanelLisa G. Shaffer. Innovations in the Early Diagnosis of Chromosomal Disorders Associated with Intellectual Disability. International Review of Research in Developmental Disabilities. vol 40, 2011, Pages 211-228. https://doi.org/10.1016/B978-0-12-374478-4.00008-3
- David T. Miller, et al. Consensus Statement: Chromosomal Microarray Is a First-Tier Clinical Diagnostic Test for Individuals with Developmental Disabilities or Congenital Anomalies. Am J Hum Genet. 2010 May 14; 86(5): 749–764. doi: 10.1016/j.ajhg.2010.04.006
- Dave BJ, et al. Role of Cytogenetics and Molecular Cytogenetics in the diagnosis of genetic imbalances. Semin Pediatr Neurol. 2007 Mar;14(1):2-6.
- WS Meschino. The child with developmental delay: An approach to etiology. Paediatr Child Health 2003;8(1):16-19