FISH Postnatal Testing
Fluorescence In Situ Hybridization (FISH) is a crucial cytogenetic technique designed to detect specific chromosomal abnormalities. It has gained prominence as a postnatal diagnostic tool due to its targeted approach, enabling the identification of various genetic conditions in newborns and children. FISH testing plays an essential role in validating prenatal results, confirming suspicions of chromosomal abnormalities, and aiding in the diagnosis of conditions caused by microdeletions, trisomies, or other chromosomal disorders.
The ACMG (American College of Medical Genetics) and ASHG (American Society of Human Genetics) emphasize the importance of FISH in genetic testing, recommending that FISH results be combined with other diagnostic tests, such as chromosome analysis, to guide clinical decisions. In a postnatal context, FISH delivers rapid, reliable insights that can transform the course of medical care for children suspected of having genetic abnormalities.
FISH testing uses a specific fluorescent dye linked to a DNA probe, designed to bind to specific regions of chromosomes. By analyzing fluorescent signals under a microscope, clinicians can detect chromosomal abnormalities at a molecular level. These abnormalities may include extra copies (trisomies), missing sections (deletions), or rearrangements of chromosomes that can affect normal development and health.
Key conditions that FISH targets include:
- Trisomy 13 (Patau Syndrome): A condition associated with severe intellectual disabilities and physical abnormalities, including heart defects.
- Trisomy 18 (Edwards Syndrome): A disorder causing slow growth, heart defects, and severe intellectual disability.
- Trisomy 21 (Down Syndrome): Characterized by developmental delays, intellectual disabilities, and distinct facial features.
- Microdeletion Syndromes: These are conditions caused by small deletions in chromosomal material, such as DiGeorge syndrome (22q11.2 deletion) or Prader-Willi syndrome.
FISH testing is different from broader genetic testing techniques, such as karyotyping or chromosomal microarray analysis (CMA), as it focuses on specific chromosomal regions rather than examining the entire genome. This targeted analysis is particularly useful when a specific genetic abnormality is suspected, and quick results are needed for medical intervention.
Clinical Utility of FISH Postnatal Testing
FISH postnatal testing offers several clinical benefits, especially in situations where precision and rapid results are crucial for medical decision-making. Some of its key applications include:
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Confirmation of Prenatal Testing Results: If prenatal tests suggest chromosomal abnormalities, FISH can be used postnatally to confirm the diagnosis. This can provide additional clarity and reassurance to both doctors and families.
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Rapid Diagnosis: FISH is an essential tool for quickly identifying genetic conditions caused by specific chromosomal abnormalities. The technique provides faster results than traditional karyotyping, often within 24-48 hours, which can be critical for immediate medical decisions.
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Targeted Genetic Analysis: FISH focuses on well-defined chromosomal regions, such as those associated with microdeletion syndromes, trisomies, or specific gene rearrangements. This targeted approach helps clinicians detect subtle genetic variations that may not be visible through broader techniques.
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Tissue-Specific Analysis: In some cases, genetic abnormalities may only be present in certain tissues or manifest as mosaicism, where different cells have different genetic compositions. FISH allows for precise analysis of specific tissues, helping to identify these complex genetic conditions.
When to Consider FISH Postnatal Testing
FISH postnatal testing is recommended in various clinical scenarios, particularly when rapid or targeted genetic information is essential for decision-making. Key situations where FISH testing should be considered include:
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Known Chromosomal Rearrangement in the Mother: If the mother carries a chromosomal rearrangement (such as a balanced translocation), there may be concerns that the baby could inherit an unbalanced form, leading to developmental challenges. FISH can confirm whether the baby has inherited such abnormalities.
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Concerns About Genetic Conditions in the Baby: When certain genetic conditions are suspected, such as trisomies or microdeletions, FISH can quickly determine if these are present. This is especially important if the baby shows physical or developmental signs consistent with a chromosomal abnormality.
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Confirmation of Other Diagnostic Results: If other prenatal or postnatal tests (such as ultrasound, NIPT, or CMA) have indicated potential chromosomal abnormalities, FISH can provide additional confirmation or clarification to solidify the diagnosis.
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Urgent Medical Intervention: In cases where immediate results are needed—such as for counseling or medical interventions—FISH offers a rapid diagnostic solution. Conditions like DiGeorge syndrome or Down syndrome can be identified swiftly, allowing families and clinicians to make informed decisions about treatment or care.
MapmyGenome Offerings for FISH Postnatal Testing
At MapmyGenome, we offer advanced FISH testing services designed to provide rapid, reliable, and precise genetic insights. Our offerings include:
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Targeted FISH Testing: We provide targeted FISH testing to detect specific chromosomal abnormalities, including trisomies and microdeletions. This test is ideal for confirming prenatal test results or investigating suspected genetic conditions in newborns and children.
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Quick Turnaround Time: Our FISH testing services deliver results within 24-48 hours, ensuring that patients and clinicians have access to timely information that is critical for making medical decisions.
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Expert Genetic Counseling: Along with our testing services, we offer comprehensive genetic counseling for families. Our team of experienced genetic counselors can help interpret the results, answer questions, and guide families through their next steps.
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Comprehensive Genetic Analysis: If FISH results suggest further testing, we can provide additional services, including chromosomal microarray analysis (CMA) or karyotyping, to deliver a more complete picture of the genetic landscape.
Test specification
|
Technique |
Variant types |
TAT |
Sample Requirements |
|
FISH |
AS + SV |
6 - 7 days |
3- 4 ml Blood in EDTA |