Overview: ELN Gene Deletion TestIntroduction: The ELN Gene Deletion Test tests for ELN gene deletions to diagnose Williams syndrome, causing developmental delays or heart defects, aiding in genetic diagnosis. Affecting 1 in 10,000 people, Williams syndrome poses diagnostic challenges due to its rarity. Following 2023 American College of Medical Genetics (ACMG) guidelines, it uses PCR/FISH for high accuracy, supporting molecular pathology screening. This test is essential for diagnosis, genetic counseling, and improving outcomes in pediatrics.
Other Names: ELN Deletion Test, Williams Syndrome Gene Assay.
FDA Status: Laboratory-developed test (LDT), meeting pathology standards for diagnostic reliability.
Historical Milestone: Genetic testing for Williams syndrome began in the 1990s with research by Ewart, who identified ELN deletions. PCR/FISH advancements in the 2000s by Abbott improved detection, surpassing earlier karyotyping methods.
Purpose: Detects ELN deletions to diagnose Williams syndrome, guides supportive therapy, and evaluates patients with developmental delays, aiming to manage symptoms.
Test Parameters: ELN gene deletion status
Pretest Condition: No special preparation required. Collect whole blood, buccal swab, or saliva. Report history of developmental issues.
Specimen: Whole Blood (EDTA, 3-5 mL), Buccal Swab (sterile swab, 1-2 swabs), Saliva (sterile container, 1-2 mL); 4 mL whole blood in EDTA tube. Transport in a biohazard container.
Sample Stability at Room Temperature: 24 hours
Sample Stability at Refrigeration: 1 week
Sample Stability at Frozen: 1 month
Medical History: Document developmental delay or heart issues. Include current medications or family history of genetic disorders.
Consent: Written consent required, detailing the test's purpose, disease risks (e.g., cardiovascular issues), and sample collection risks.
Procedural Considerations: Uses PCR/FISH to detect deletions, requiring labs with thermal cyclers or fluorescent microscopes. Results available in 5-7 days. Performed in labs with strict handling.
Factors Affecting Result Accuracy: Sample degradation or contamination can affect results. Medications may not affect results but require correlation.
Clinical Significance: Positive deletion confirms Williams syndrome, guiding therapy. Early diagnosis might improve management, while untreated cases lead to complications. Normal results may require imaging.
Specialist Consultation: Consult a pediatrician or genetic counselor for interpretation.
Additional Supporting Tests: Echocardiogram, developmental assessment, or genetic panel to confirm diagnosis.
Test Limitations: Specific to ELN gene; correlation with symptoms needed. False negatives possible with mosaicism.
References: ACMG Guidelines, 2023; American Journal of Human Genetics, Ewart AK, 2022.
