Adenosine Deaminase Deficiency: Phenotypic Spectrum

Phenotype 1, 2Proportion of Persons w/ADA DeficiencyComment
Typical early-onset severe combined immunodeficiency (ADA-SCID)~80%Diagnosed in infancy
Less severe "delayed"/"late-onset" combined immunodeficiency (ADA-CID) 315%-20%Diagnosed in older children & adults
Benign "partial ADA deficiency"--Discovered by screening populations or relatives of persons w/ADA-SCID for deficiency of erythrocyte ADA activity

ADA = adenosine deaminase

1.

For other genetic causes of combined immunodeficiency, see Differential Diagnosis.

2.

For ADA enzyme levels associated with these phenotypes, see Genotype-Phenotype Correlations.

3.

ADA-CID may also be referred to as "leaky SCID."

From: Adenosine Deaminase Deficiency

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