Patau syndrome, also known as trisomy 13, is caused by having an extra copy of chromosome 13 in some or all of the body's cells.
Here's a more detailed explanation:
Understanding Chromosomes and Trisomy
Normally, each cell in the human body contains 23 pairs of chromosomes, totaling 46. These chromosomes carry our genes, which determine our traits. We inherit one set of 23 chromosomes from each parent.
In Patau syndrome (trisomy 13), there is an error during cell division, resulting in an extra, or third, copy of chromosome 13. This extra genetic material disrupts normal development, leading to the characteristics of Patau syndrome.
Types of Trisomy 13
There are three main types of trisomy 13:
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Full Trisomy 13: This is the most common type, where every cell in the body has the extra chromosome 13.
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Mosaic Trisomy 13: In this case, only some of the body's cells have the extra chromosome 13. The severity of the syndrome can vary depending on the percentage of cells with the extra chromosome.
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Partial Trisomy 13 (Translocation): Part of chromosome 13 is attached to another chromosome. While the individual has only two copies of chromosome 13 material, the extra piece causes Patau syndrome. This can sometimes be inherited from a parent who carries a balanced translocation.
Causes of the Extra Chromosome
The presence of the extra chromosome 13 is usually due to a random event during the formation of eggs or sperm. This event is called nondisjunction, where chromosomes fail to separate properly. The risk of nondisjunction increases with the mother's age, but it can happen at any age. In cases of translocation, where a piece of chromosome 13 is attached to another chromosome, this can be inherited from a parent. However, de novo translocations, or new translocations, can also arise spontaneously.
In summary, Patau syndrome arises from an error in chromosome segregation, leading to an extra copy (or part) of chromosome 13 in the body's cells. This excess genetic material disrupts normal development and causes the various features associated with the syndrome.
