# Case Report: A simple case of drug-induced secondary antibody deficiency or a rare primary immune deficiency?

## TL;DR

This case report discusses a patient with antibody deficiency, highlighting the challenge of determining if it is due to a rare genetic condition or a medication side effect.

## Contribution

The case emphasizes the value of genetic testing in diagnosing complex immune deficiencies and guiding patient care.

## Key findings

- Distinguishing between primary and secondary antibody deficiency can be challenging.
- Genetic assessment can reveal underlying causes in patients with complex immune phenotypes.
- Accurate diagnosis impacts long-term management of antibody deficiency.

## Abstract

Antibody deficiency may be primary, because of an underlying inborn error of immunity, or secondary, due to another disease process or medication, leading to decreased antibody production or increased antibody loss. Secondary antibody deficiency is much more common than primary. It can, however, be difficult to distinguish primary from secondary, and both should be considered when assessing patients with hypogammaglobulinaemia. The case presented highlights the importance of confirming the underlying pathophysiology in patients presenting with antibody deficiency, the contribution of genetic assessment to the care of patients with complex phenotypes, and the impact this can have on long-term patient management.