What is the effect of adenosine deaminase deficiency (ADA) on red blood cells?

Adenosine deaminase deficiency (ADA) is an autosomal recessive metabolic disorder that causes immunodeficiency. Without treatment, this condition is fatal and, due to the severity of the disease, requires early and consistent treatment.
This deficiency directly affects the red blood cells of an affected individual through the inhibition of the enzyme Adenosylhomocysteine hydrolase, which catalyses hydrolysis of AdoHcy to adenosine and homocysteine, and through the over-accumulation of the nucleotide deoxyadenosine triphosphate, which is used in cells for DNA synthesis or replication.
Particularly, red blood cells in the thymus and the spleen are often highly affected by adenosine deaminase deficiency. Particularly, the amount of accumulation of deoxyadenosine triphosphate in red blood cells of ADA-deficient patients is used as a measuring tool to assess the severity of this metabolic disorder