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.
The research group, headed by Dr. Lukas Sommer at the Swiss Federal Institute of Technology, has identified a heretofore unknown role for the TGF cell-to-cell signaling pathway in the pathogenesis of DiGeorge syndrome.
The inherited causes are related to defects in the genes that play a role in lymphocyte development. 1  Some key examples of these diseases are: 2  DiGeorge anomaly. 3  Wiskott-Aldrich syndrome. 4  Severe combined immunodeficiency syndrome. 5  Ataxia-telangiectasia.