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FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
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SNP Microarray in FISH Negative Clinically Suspected 22q11.2 Microdeletion Syndrome.
Ashutosh Halder1, Manish Jain1, Amanpreet Kaur Kalsi1
1Reproductive Biology, AIIMS, New Delhi 110029, India.
Scientifica
|April 7, 2016
Summary
SNP microarray effectively detects 22q11.2 microdeletions and microduplications, especially in FISH-negative cases. This method is recommended as a first-line screening test for suspected genetic disorders, particularly in neonates.
Area of Science:
- Genetics
- Molecular Biology
- Clinical Diagnostics
Background:
- 22q11.2 microdeletion syndrome is a common genetic disorder.
- Fluorescence in situ hybridization (FISH) is a standard diagnostic tool.
- FISH can be noninformative or normal in some clinically suspected cases.
Purpose of the Study:
- To evaluate the utility of SNP microarray in diagnosing 22q11.2 microdeletion syndrome.
- To compare SNP microarray with FISH in a cohort of clinically suspected cases.
- To identify additional chromosomal abnormalities and copy number variations (CNVs).
Main Methods:
- SNP microarray analysis using 300K HumanCytoSNP-12 or CytoScan 750K arrays.
- Evaluation of 101 cases with suspected 22q11.2 microdeletion syndrome.
- Analysis of results in conjunction with FISH findings.
Main Results:
- SNP microarray detected 22q11.2 microdeletions/microduplications in approximately 8% of cases.
- The diagnostic yield was highest in cases with noninformative or normal FISH results.
- Additional pathogenic CNVs, chromosomal abnormalities, and uniparental disomy (UPD) loci were identified.
Conclusions:
- SNP microarray is a valuable tool for diagnosing 22q11.2 microdeletions, particularly when FISH is inconclusive.
- Stricter clinical criteria for FISH testing are suggested.
- SNP microarray should be considered the initial screening test for neonates with unclear clinical presentations, while FISH remains useful for mosaicism, family screening, and prenatal diagnosis in confirmed cases.
