SNP Shot: Genomic Insights

Adenosine deaminase 2 (ADA2) deficiency is a condition marked by unusual inflammation in different parts of the body. The signs and symptoms can appear at any age, from young childhood through adulthood. The seriousness of the condition also differs from person to person, even within the same family.

Inflammation is a typical immune response to injuries and foreign substances like bacteria. However, in ADA2 deficiency, inflammation occurs abnormally and without a clear cause, damaging the body's tissues and organs, particularly blood vessels. This blood vessel inflammation is called vasculitis. Other areas affected by this abnormal inflammation can include the skin, digestive system, liver, kidneys, and nervous system. Depending on how severe and where the inflammation is, the condition can be disabling or even deadly.

The signs and symptoms of ADA2 deficiency can include recurring fevers that come and go, a net-like, mottled discoloration of the skin known as livedo racemosa, an enlarged liver and spleen (hepatosplenomegaly), and repeated strokes affecting deep brain structures, which can begin in early childhood. In some individuals, ADA2 deficiency leads to further immune system problems, increasing the risk of bacterial and viral infections.

ADA2 deficiency is sometimes referred to as a type of polyarteritis nodosa (PAN), a disorder causing widespread inflammation of blood vessels throughout the body (systemic vasculitis). However, some researchers don't classify ADA2 deficiency as a form of PAN.

Inheritance:

The inheritance pattern of this condition is autosomal recessive. This means that both copies of the relevant gene in each cell must have mutations for the condition to develop. Individuals with autosomal recessive conditions inherit one mutated copy of the gene from each parent, who usually don't show any signs or symptoms of the condition themselves.