Karyotyping in Dehradun

What is a Karyotyping?

Karyotyping examines a person's chromosomes directly under the microscope. Cells, usually white blood cells, are cultured in the laboratory until they divide, arrested at the stage where chromosomes are most visible, then stained, photographed and arranged in order so that number and structure can be assessed. The culture step is why the report takes two to three weeks rather than days. It detects abnormalities of number, such as the extra chromosome 21 of Down syndrome or the missing X of Turner syndrome, and large structural changes such as translocations, deletions and inversions. Its limitation is resolution: it sees large-scale changes but cannot detect small deletions or single-gene mutations, for which chromosomal microarray or gene sequencing is needed. In reproductive medicine its commonest use is in couples with recurrent miscarriage, where one partner may carry a balanced translocation, meaning all the genetic material is present but rearranged. Such a person is entirely healthy but produces a proportion of unbalanced eggs or sperm, which explains repeated losses and opens specific options.

Why take this test?

Karyotyping is advised for recurrent pregnancy loss, generally after three or more miscarriages, where both partners are tested to look for a balanced translocation. It is used in the investigation of infertility, particularly in men with very low or absent sperm counts and in women with premature ovarian insufficiency or primary absence of periods. It is indicated in a child with developmental delay, multiple congenital abnormalities, unexplained short stature, or ambiguous genitalia, and in a newborn with features suggesting a chromosomal syndrome. It is also used on products of conception after a miscarriage to establish whether a chromosomal cause was responsible, which is often reassuring for the couple. Because the results carry genetic implications for family members and for future pregnancies, testing should be accompanied by genetic counselling rather than the report simply being handed over, and your doctor will usually arrange that alongside.

• Three or more miscarriages, with both partners tested
• Infertility, especially very low or absent sperm counts
• Premature ovarian insufficiency or primary absence of periods
• A child with developmental delay or multiple congenital abnormalities
• Unexplained short stature or ambiguous genitalia
• Investigating products of conception after miscarriage

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