<unk>  has an autosomal recessive pattern of inheritance. The enzyme adenosine deaminase is encoded by the ADA gene on chromosome 20. ADA deficiency is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome (chromosome 20 is an autosome), and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder. Age of onset and severity is related to some 29 known genotypes associated with the disorder.
Adenosine deaminase deficiency
Adenosine deaminase 2 deficiency
Adenine phosphoribosyltransferase deficiency
Guanidinoacetate methyltransferase deficiency
Galactose-1-phosphate uridylyltransferase deficiency
Methylenetetrahydrofolate reductase deficiency
Mevalonate kinase deficiency
Adenosine monophosphate deaminase deficiency type 1