XRCC4 protein is aĀ TETRAMER that resembles the shape of a DUMBBELL containing two globular ends separated by a long, thin stalk. The tetramer is composed of twoĀ dimers, and each dimer is made up of two similarĀ subunits. The first subunit (L) contains amino acid residues 1 – 203 and has a longer

Adenosine deaminase deficiencyĀ (ADA deficiency) is aĀ metabolic disorderĀ that causesĀ immunodeficiency. It is caused by mutations in theĀ ADA gene. It accounts for about 10–15% of all cases ofĀ autosomalĀ recessiveĀ forms ofĀ severe combined immunodeficiencyĀ (SCID) among non-inbredĀ populations