In this task, you will be given a sentence. You need to reconize the name of the disorder or disease. Disease is a disorder of structure or function in a human, animal, or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury. Although there might be several correct answers, you need to write one of them.

 Patients were selected because they were heterozygous or homozygous for C2 deficiency .
C2 deficiency