Definition is a rhetorical mode that can be used in something smaller or shorter than a full paper. You can use extended definition for several paragraphs only in a paper of much greater length. You also can add to a paper a one-paragraph definition--like a brief encyclopedia definition.
Immunodeficiency: Therapies include thymus transplantation and adoptive transfer of mature T cells (ATMTC) for individuals with complete DiGeorge syndrome and appropriate prophylaxis measures and monitoring autoimmune complications for incomplete or partial DiGeorge syndrome.
Using the FISH test for 22q11.2, it was discovered that about 95% of patients with DiGeorge syndrome and VCFS have a deletion. This special FISH test for 22q11.2 deletions is available in many clinical laboratories that look at chromosomes (referred to as cytogenetics laboratories).