Immunodeficiency due to conditions classified elsewhere

**Excludes1:** - certain disorders involving the immune mechanism (D80-D83, D84.0, D84.1, D84.9) - human immunodeficiency virus [HIV] disease (B20)

**Code first:** - underlying condition, such as: - chromosomal abnormalities (Q90-Q99) - diabetes mellitus (E08-E13) - malignant neoplasms (C00-C96)