A patient with Pitt–Hopkins syndrome with concomitant common variable immunodeficiency.

In patients with 18q deletion syndrome (18q‐), immunodeficiency, autoimmunity, and allergies have been described in a subset. Pitt–Hopkins syndrome represents a specific subset of patients with 18q‐ who have a proximal deletion involving the TCF4 gene or a TCF4 variant. Immunodeficiency has been reported in the overall 18q‐ population; however, immunodeficiency with Pitt‐Hopkins syndrome has not been highlighted. This case report details the immunologic evaluations and the associated infections seen in a young adult with Pitt–Hopkins syndrome to underscore the challenges of managing adults with a complex phenotype who develop frequent infections. This patient with Pitt–Hopkins syndrome ultimately fulfilled the diagnostic criteria for common variable immunodeficiency. Immunoglobulin replacement has led to a somewhat improved infection pattern, although she continues to have aspiration events leading to pneumonia. This case highlights the clinical evolution of Pitt–Hopkins syndrome and serves as a reminder that immunodeficiency can occur in this syndrome. [ABSTRACT FROM AUTHOR]