Which are the causes of Pallister-Killian Syndrome / Tetrasomy 12p?

Pallister-Killian Syndrome, also known as Tetrasomy 12p, is a rare genetic disorder caused by the presence of extra genetic material on the short arm of chromosome 12. This condition is characterized by a wide range of physical and developmental abnormalities.

The exact cause of Pallister-Killian Syndrome is not well understood. It is believed to occur sporadically, meaning it is not typically inherited from parents. The condition is caused by a random error during early embryonic development, known as a mosaic chromosomal abnormality. Mosaicism refers to the presence of two or more genetically distinct cell lines within an individual's body. In the case of Pallister-Killian Syndrome, some cells have the normal chromosomal makeup, while others have the extra genetic material on chromosome 12.

The extra genetic material in Pallister-Killian Syndrome is a result of a specific genetic alteration called isochromosome 12p. This alteration occurs when a chromosome breaks and then reattaches in a mirror image fashion, resulting in two copies of the short arm of chromosome 12 instead of one. The presence of this extra genetic material disrupts normal development and leads to the characteristic features of the syndrome.

While the exact cause of the chromosomal error leading to Pallister-Killian Syndrome is unknown, certain risk factors may increase the likelihood of its occurrence. Advanced maternal age at the time of conception has been associated with an increased risk of chromosomal abnormalities in general, including mosaic conditions like Pallister-Killian Syndrome. However, it is important to note that the majority of children born to older mothers do not have this syndrome.

Pallister-Killian Syndrome affects individuals of all ethnic backgrounds and both sexes equally. The condition is typically diagnosed based on clinical features and confirmed through genetic testing, such as a chromosomal analysis of skin cells.

It is important to note that Pallister-Killian Syndrome is a rare disorder, and the information available about its causes and risk factors is limited. Ongoing research is being conducted to further understand the underlying mechanisms and genetic factors involved in the development of this syndrome.