Karyotyping by G-Banding Peripheral Blood

Karyotyping is carried out to:

• To determine whether an adult's chromosomes contain an alteration that might be passed on to a child.
• See if a chromosome defect prevents a woman from getting pregnant or if it causes miscarriages.
• Check to see if a fetus has a chromosomal defect.
• Karyotyping can also determine whether chromosomal issues led to the fetus's stillbirth.
• Find the cause of any congenital disabilities or disabilities in a newborn.
• Assist in determining the best course of treatment for certain cancers.

• Patients with infertility (both male and female), poor obstetric history, puberty-related difficulties, or a family history of specific genetic illnesses may need to undergo chromosomal analysis. If infants or early toddlers exhibit evidence of intellectual incapacity or congenital malformations, a chromosomal study may be necessary. There are some blood malignancies and diseases for which this test may be used.

A karyotype test evaluates the shape, size, and number of chromosomes, which are parts of the cells containing genes. Genes are parts of DNA passed down from one's mother and father. It is usually performed to detect genetic abnormalities that a developing baby has.

This test is useful for the following reasons:

• To find trisomies, monosomies, etc.
• Determine the number of chromosomes.
• Check for chromosome structural alterations, such as deletions, duplications, translocations, etc.

Karyotyping test requires a blood sample. A tourniquet (elastic) band is placed tightly on the upper arm. The patient is then asked to make a fist. This helps in the build-up of blood filling the veins. The skin is disinfected before needle insertion and the blood sample is collected in vacutainer.

Adults may need Karyotyping testing if they:

• Have issues getting pregnant or their partner pregnant. Occasionally infertility in men or women can be caused by a genetic defect.
• Have certain blood disorders or cancers. Chromosome changes can occur due to illnesses, including multiple myeloma, lymphoma, leukaemia, or anaemia. Karyotyping can detect these anomalies and help with treatment.
• Have a family history of particular genetic illnesses. Chromosome analysis can reveal whether one has abnormal chromosomes and how likely it is to be passed on to offspring.

Complete Process

• Karyotype testing can be performed using almost any tissue or cell from the body. 
• A blood sample drawn from a vein is typically used for a karyotype test.

Blood sample from a vein

The healthcare worker taking the blood will:

i. Tie an elastic band across the upper arm to prevent blood flow. This enlarges the veins underneath the band, making it easier to insert a needle.

ii. Use alcohol to clean the needle site.

iii. Insert the needle into the vein. They might use more than one needle.

 iv. Affix a tube to the needle to fill it with blood.

v. Untie the band from the arm when enough blood has been collected.

vi. Place a cotton ball or gauze pad above the needle site once the needle is removed.

vii. Bandage the area after applying pressure to the site.

• A placenta or amniotic fluid sample could be used for testing during pregnancy. Cells from the fetus are extracted utilising chorionic villus sampling or amniocentesis.
• In addition, a Karyotype Test may be performed via a bone marrow aspiration.

Precautions to Be Taken

There is no particular preparation needed for this test. One can get advice from a genetic counsellor or a specialist doctor to make sound decisions. Before choosing to get a genetic test, request genetic counselling.

After The Test

A blood test carries no substantial risks, although one could experience the following:

• Light bleeding at the site of the vein puncture.
• Soreness inside the arms.

Abnormal karyotype test results could indicate that the parent or the child has atypical chromosomes. This could be an indication of genetic illnesses and disorders, like:

• Edwards syndrome, also referred to as trisomy 18, results in severe problems with the heart, kidneys, and lungs.
• Down syndrome, trisomy 21, results in intellectual disabilities and developmental delays.
• Turner syndrome inhibits female traits from developing in girls and women.
• Patau syndrome results in low birth weight and poor development in the womb.

Results as expected are 46XX or 46 XY. Abnormal results are reviewed with the clinician and made public if they are the consequence of a hereditary abnormality or disorder.

A normal karyotyping result does not necessarily rule out the potential of a genetic disease that is not amenable to karyotyping. In these situations, confirmation using additional techniques is required. Cell growth may be impacted in some circumstances when there is a lag in transportation or problems with sample integrity (clotted/haemolysed), as karyotyping necessitates the culture of live cells. A second sample may be needed in certain circumstances.

It could be done on the following individuals:

• a fetus using chorionic villi or amniotic fluid (placental tissue).
• If a woman's findings from one or maybe more pregnancy screening tests are abnormal.
• If a pregnant woman is undergoing an amniotic fluid study because it is believed that she has a higher-than-average risk of having a child with a congenital disability.
• if a known chromosomal issue runs in the family
• a woman or a couple should evaluate their chromosomal makeup before getting pregnant, especially if the woman has had a history of infertility or miscarriage.

When a woman experiences miscarriage or infertility, when a newborn has congenital abnormalities, when an adult exhibits symptoms of a genetic condition, or when a fetus is suspected to have a chromosomal abnormality, chromosome analysis may be prescribed.

When a chromosomal issue has been identified in a kid or another family member, other members of the family may also be requested to go for chromosome test.

When a person has leukemia, lymphoma, myeloma, refractory anemia, or other forms of cancer, it may be required to look for acquired chromosomal abnormalities.

if the family history has a known chromosomal abnormality.

No special preparation is required.

Depending on the results, doctors may recommend other forms of genetic testing for further prognosis.

G-Banding

Chromosome Analysis

Karyotype Genetic Test