Chromosomal and genetic tests before pregnancy and after birth when and why are they requested

In modern medicine, genetic and chromosomal tests have become essential tools for uncovering the root causes of inherited disorders, birth defects, and even certain types of cancer. These advanced tests can reveal abnormalities that are often missed by routine examinations.In this comprehensive article from Dalili Medical, we provide a clear and simple guide to genetic and chromosomal testing—what they are, when they are recommended, and how to interpret their results.

✅ What’s the Difference Between Genes and Chromosomes?

Chromosomes are structures inside the nucleus of each cell that contain genetic material (DNA). A typical human has 46 chromosomes arranged in 23 pairs.
Genes are smaller units within chromosomes that carry the codes for making proteins and determine inherited traits.

Any abnormality in the number, structure, or sequence of genes or chromosomes can lead to genetic disorders.

What Are Chromosomal Tests?

Karyotype Test
A test that visually examines the number and shape of chromosomes.
✅ Useful for diagnosing:
- Down Syndrome (extra chromosome 21)
- Turner Syndrome
- Sex chromosome disorders (X and Y abnormalities)
FISH (Fluorescence In Situ Hybridization)
Detects specific changes in chromosomes using fluorescent probes.
✅ Used for:
- Certain cancers
- Prenatal abnormalities
Chromosomal Microarray Analysis (CMA)
Detects tiny deletions or duplications in chromosomes that may not appear in a standard karyotype.
✅ More precise than a basic karyotype test.

What Are Genetic Tests?

DNA Sequencing
Examines the exact sequence of DNA to identify mutations.
✅ Used to diagnose rare diseases or genetic risk factors.
Targeted Mutation Testing
Focuses on specific genes linked to diseases, such as:
- BRCA1 and BRCA2 (linked to breast cancer)
Whole Genome Sequencing
Analyzes the entire DNA sequence.
✅ Extremely comprehensive but expensive.

⏱️ When Are These Tests Recommended?

Suspected genetic disorders (e.g., autism, developmental delays, muscle weakness)
Cases of infertility or recurrent miscarriages
Congenital abnormalities or intellectual disabilities
To help diagnose cancer types (e.g., leukemia, hereditary breast cancer)
Prenatal screening for fetal abnormalities
Family history of genetic conditions

How Are These Tests Performed?

A sample of blood, saliva, or tissue is collected, depending on the test.
In prenatal testing, samples may be taken from amniotic fluid or placenta.
The sample is sent to a specialized genetic laboratory for analysis.

Interpreting the Results

Chromosome Test Results:

Normal: 46 chromosomes with no structural issues.
Numerical abnormality: e.g., an extra chromosome (47), such as in Down syndrome.
Structural abnormality: deletion, inversion, or translocation of chromosomal segments.

Genetic Test Results:

Pathogenic mutation: confirms presence or risk of disease.
Benign mutation: not associated with any health condition.
Variant of uncertain significance (VUS): unclear impact—requires more analysis or family testing.

⚠️ Important: All results should be interpreted by a genetic specialist, as some mutations do not necessarily indicate disease.

✅ Benefits of Genetic and Chromosomal Testing

Accurate diagnosis of inherited diseases
Early detection of hereditary cancers
Support for personalized medicine and targeted treatment
Genetic counseling before marriage or pregnancy
Risk assessment for familial genetic disorders

⚠️ Are There Any Risks Involved?

The tests themselves are safe and non-invasive.

The main risks are emotional or social, including:

Anxiety about the results
Impact on reproductive decisions

This is why genetic counseling is strongly recommended before and after testing.

❓ Frequently Asked Questions

Are genetic tests 100% accurate?
Not completely, but they are highly sensitive. Some mutations may go undetected or be difficult to interpret.

Do genetic tests detect all diseases?
No. They can only identify conditions that are linked to known genetic mutations.

Can children undergo genetic testing?
Yes, especially if there are clear symptoms or a strong family history of genetic conditions.

✅ Summary

Chromosomal and genetic tests are powerful tools in modern medicine, helping uncover the root causes of complex hereditary diseases. While they don't replace clinical evaluation, they provide deep insights into human health at the molecular level.

Daleeli Medical Tip:
If you have a family history of genetic conditions, are planning to have children, or experience unusual health symptoms—don’t hesitate to consult a genetic specialist and consider appropriate testing.