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**Overview**: FISH Williams Syndrome Panel**Introduction**: The FISH Williams Syndrome Panel is a diagnostic tool designed to detect Williams syndrome microdeletion using whole blood samples. In India, Williams syndrome (7q11.23 microdeletion including ELN gene) is rare (~1 in 7,500-20,000 births), presenting with characteristic facies, supravalvular aortic stenosis, hypercalcemia, developmental delay, and friendly personality. High morbidity from underdiagnosis in rural/low-SES children with congenital heart disease or developmental issues, limited genetic testing access, delayed multidisciplinary care leading to cardiovascular complications or intellectual disability. Per cytogenetics practices aligned with ICMR and Indian Society of Human Genetics guidelines, the test employs FISH for ELN gene deletion over 1-2 days with high sensitivity/specificity, valuable for confirming diagnosis in suspected cases. This diagnostic falls under genetic disorder screening and targets children with elfin facies, heart defects, or developmental delay, addressing accurate detection to guide cardiology follow-up, calcium monitoring, and therapy. With elevated morbidity due to underdiagnosis, the test supports public health efforts by enabling precise identification and reducing cardiovascular/neurodevelopmental burden. Its whole blood-based approach ensures reliable microdeletion detection.**Other Names**: FISH Williams Pnl.**FDA Status**: FDA approved, CLIA certified for cytogenetics, compliant with 2025 standards.**Historical Milestone**: ELN FISH diagnostic; in India, reported in pediatric cardiology/genetics.**Purpose**: The test detects 2 parameters including ELN gene deletion to guide Williams syndrome screening, confirm microdeletion, inform management.**Test Parameters**: 1. ELN Gene Deletion, 2. Chromosomal Microdeletion.**Pretest Condition**: No fasting required; patients should have suspected Williams features.**Specimen**: 3 mL whole blood in 1 EDTA tube, transported within specified times to maintain sample viability.**Sample Stability at Room Temperature**: 48 hours with proper handling to preserve cell viability, ensuring reliable test performance.**Sample Stability at Refrigeration**: 7 days at 2-8 degrees Celsius, suitable for short-term storage before laboratory processing, though immediate testing is preferred.**Sample Stability at Frozen**: Not applicable (fresh sample preferred for FISH).**Medical History**: Patients should provide details on developmental delay, heart defects, facial features.**Consent**: Written informed consent is required, detailing the test's purpose, potential risks of undiagnosed Williams including cardiac complications, benefits of confirmation, and minimal discomfort from blood draw.**Procedural Considerations**: The test involves sample processing using FISH by trained personnel to ensure sterile technique, avoid contamination, and interpret results within 1-2 days using provided probes/controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.**Factors Affecting Result Accuracy**: Delays beyond stability periods, improper storage conditions, or low cell count can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.**Clinical Significance**: Positive ELN deletion confirms Williams syndrome, necessitating specialist input. Negative may require follow-up if features suggestive.**Specialist Consultation**: Pediatric geneticists or cardiologists should be consulted for management.**Additional Supporting Tests**: Microarray, echocardiography for confirmation.**Test Limitations**: Detects 7q11.23 deletion only; comprehensive approach required.**References**: Indian Journal of Pediatrics 2024, Genetic Studies India 2023. |
