Clinical Outcomes of a Cohort Study on Patients with CD40L Deficiency

CD40 ligand (CD40L) deficiency is an X-linked form of hyper Immunoglobulin M syndrome (XHIGM) that is caused by mutations of CD40Lgene. The aim of the present study was to investigate the clinical and molecular basis of this disorder in a group of Iranian patients with a long period of follow-up.

A total number of 21 patients diagnosed with X-HIGM, who were referred to and followed up at Children’s Medical Center (Pediatrics Center of Excellence affiliated to Tehran University of Medical Sciences, Tehran, Iran), were included in this retrospective cohort study. The medical and immunologic evaluations of patients were followed by mutation analysis to confirm the diagnosis.

The median age of all participants was 7.50 (4.87-16.25) years. The median age at the time of disease onset was 8.00 (6.00-13.50) months. The majority of patients showed their first manifestation before 4 years of age. The median age of diagnosis was 23.00 (12.50-48.00) months, with a median diagnostic delay of 9.00 (1.50-28.00) months. Anemia was the most common hematologic manifestation, occurring in 71.4% of the patients. The median serum IgM concentration was 206 (82-335) mg/dL. Elevated IgM levels were observed in fifteen patients based on age-references and six patients had normal IgM levels. The mutation analysis among patients with the CD40L mutations revealed 15 missense, 5 frameshift-nonsense, and 1 splice-site mutation. Eight patients (38%) died during the study period. Respiratory infection such as pneumonia were the main cause of death in the 5 patients.

Earlier diagnosis of X-HIGM may provide effective management and lead to patients’ survival and better quality of life. Moreover, using whole-exome sequencing for detection of patients with HIGM phenotype is strongly recommended to differentiate it from intrinsic humoral immunity defects and to initiation the appropriate therapeutic procedures and management.