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**Overview**: FISH Prader-Willi SNRPN Panel**Introduction**: The FISH Prader-Willi SNRPN Panel is a diagnostic tool designed to detect Prader-Willi syndrome microdeletion using whole blood samples. In India, Prader-Willi syndrome (15q11-13 paternal deletion or maternal uniparental disomy) is rare (~1 in 10,000â€"30,000 births), presenting with neonatal hypotonia, feeding difficulties, hyperphagia, obesity, developmental delay, and hypogonadism. High morbidity from underdiagnosis in rural/low-SES children with failure to thrive or obesity, limited genetic testing access, delayed growth hormone therapy and behavioral management leading to severe obesity-related complications (diabetes, cardiac). Per cytogenetics practices aligned with ICMR and Indian Society of Human Genetics guidelines, the test employs FISH for SNRPN 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 infants/children with hypotonia, poor feeding, or obesity, addressing accurate detection to guide multidisciplinary care and family counseling. With elevated morbidity due to underdiagnosis, the test supports public health efforts by enabling precise identification and reducing long-term disability. Its whole blood-based approach ensures reliable microdeletion detection.**Other Names**: FISH PWS Pnl.**FDA Status**: FDA approved, CLIA certified for cytogenetics, compliant with 2025 standards.**Historical Milestone**: SNRPN FISH diagnostic; in India, used in pediatric genetics.**Purpose**: The test detects 2 parameters including SNRPN gene deletion to guide Prader-Willi syndrome screening, confirm microdeletion, inform management.**Test Parameters**: 1. SNRPN Gene Deletion, 2. Chromosomal Microdeletion.**Pretest Condition**: No fasting required; patients should have suspected Prader-Willi 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 neonatal hypotonia, feeding issues, obesity onset.**Consent**: Written informed consent is required, detailing the test's purpose, potential risks of undiagnosed Prader-Willi including obesity 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 SNRPN deletion confirms Prader-Willi, necessitating specialist input. Negative may require follow-up if features suggestive.**Specialist Consultation**: Pediatric geneticists or endocrinologists should be consulted for management.**Additional Supporting Tests**: Methylation analysis, microarray for confirmation.**Test Limitations**: Detects deletion only; comprehensive approach required.**References**: Indian Journal of Pediatrics 2024, Genetic Studies India 2023. |
