Severe combined immunodeficiency disease (SCID)


Good news!   

Your horse is clear of severe combined immunodeficiency disease and does not have the gene mutation.

Your horse cannot pass on the severe combined immunodeficiency disease mutation.

There are no breeding or performance implications.

What is severe combined immunodeficiency disease (SCID)?

Severe combined immunodeficiency disease is an inherited genetic disease caused by the PRKDC gene. This mutation impairs the mechanism necessary to make functional immune cells. Foals usually appear healthy at birth but die of infection within the first 6 months. This is a lethal condition. Sadly, there is no cure or treatment.

Genomic Details

The mutation that causes severe combined immunodeficiency disease (SCID) is a deletion in the PRKDC gene. This is when part of the gene is deleted. A small deletion of on this gene reduces the activity of a protein called DNA-PK. When this happens, there is a reduction in B and T cells that help the immune system to fight infections and viruses. This means the foal completely lacks an immune system, dying before the age of three months.

A horse’s genetic result for severe combined immunodeficiency disease (SCID) is one of three possibilities:

  • Not deleted / Not deleted: Does not have the disease. Does not have the mutation.

  • Not deleted / Deleted: Carrier. Does not have the disease. Carries one gene mutation from one parent. This might be passed to the foal.

  • Deleted / Deleted: Affected. Has the genetic disease. The horse has inherited a gene mutation from each parent. One mutation will be passed to their foal.