FISH - Prenatal
The ACMG & ASHG issued a joint position statement on FISH “For management of the fetus, it is reasonable to report positive FISH test results. Clinical decision-making should be based on information from two of three of the following: positive FISH results, confirmatory chromosome analysis, or consistent clinical information.”1
FISH (Fluorescence In -Situ Hybridization) is a cytogenetic test for common chromosomal abnormalities such as Trisomy 13, Trisomy 18, Trisomy 21. In this technique, a Specific fluorescent dye coupled to a probe complementary to a particular chromosome region. FISH targets only limited regions of the genome
Clinical utility
- FISH is highly effective in detecting common chromosomal aneuploidies,
- FISH offers a quick turnaround time, allowing for timely decision-making in prenatal care.
- Targeted Analysis: FISH is a targeted test that focuses on specific chromosomal regions.
- FISH results can guide further diagnostic testing, such as chromosomal microarray analysis (CMA) or karyotyping, to obtain a comprehensive assessment of the fetal chromosomal profile.
When is it recommended
- Iin cases with a high risk or suspicion of specific chromosomal aneuploidies .
- When rapid results are needed, allowing for timely decision-making in pregnancy management.
- FISH is particularly valuable for targeted investigation of specific chromosomal abnormalities associated with known microdeletion/microduplication syndromes or chromosomal rearrangements.
Test specification
| Technique | Variant types | TAT | Sample requirements |
|---|---|---|---|
| FISH | AS + SV | 6 - 7 days | Amniotic Fluid, CVS(chorionic villus sample) |
References
- Test and Technology Transfer Committee. Technical and clinical assessment of fluorescence in situ hybridization: an ACMG/ASHG position statement. I. Technical considerations. Genet Med. 2000 Nov-Dec; 2(6): 356-61.
FAQs
Are there any limitations or drawbacks to FISH in prenatal testing?
FISH is a targeted test that focuses on specific chromosomal regions, which means it can only detect the abnormalities it is designed to identify. It may not detect all chromosomal abnormalities or gene-level mutations. If additional abnormalities are suspected, further genetic testing may be required.
