Yang Wen-kuang, director of the cancer laboratory at the National Health Research Institute and a planner for the Genetic Medicine Technology Program, explains that sufferers from severe combined immunodeficiency disorders lack the genes responsible for producing adenosine deaminase (ADA), an enzyme which is required by lymphocytes in the blood to metabolize adenosine. Without the enzyme, the lymphocytes die off and are unable to provide an immune function.
協助規劃國家「基因醫藥衛生科技」計畫、國家衛生研究院癌症合作實驗室主任楊文光指出，嚴重聯合免疫缺乏症患者由於遺傳性的基因缺損，血液中的淋巴細胞缺乏該基因產生的酵素（腺甘酸去胺酵素），因而無法代謝腺甘酸，淋巴細胞很快死亡，不能發揮其細胞性和體液性的免疫機能。