[The hyper-IgM syndrome: 13 observations]

Area of Science:

• Immunology
• Genetics
• Pediatrics

Background:

• Hyper-IgM syndrome (HIGM) is a rare primary immunodeficiency characterized by low IgG and IgA with normal or elevated IgM.
• Clinical manifestations predominantly involve recurrent infections of the digestive tract, ears, nose, throat, and lungs.

Purpose of the Study:

• To describe the clinical and immunological characteristics of hyper-IgM syndrome in a Tunisian cohort.
• To identify specific features of HIGM in this population, including genetic forms and associated complications.

Main Methods:

• Retrospective study of medical records from 13 patients (10 boys, 3 girls) from 12 families.
• Diagnosis confirmed by measuring serum immunoglobulin levels (IgG, IgA, IgM) using Mancini's technique.
• Assessment of CD40 ligand expression and cellular immune function in a subset of patients.

Main Results:

• The mean age of onset was 20 months, with recurrent infections being the primary symptom (digestive, respiratory, cutaneous, glandular).
• Constant IgG deficiency and IgA deficiency in 12 patients; elevated IgM in 10 patients.
• CD40 ligand deficiency observed in boys; neurological manifestations in 2 patients; 11 patients had cellular immune deficiency.
• Intravenous immunoglobulin therapy improved infection manifestations; one patient died of Burkitt lymphoma.

Conclusions:

• Primary hyper-IgM syndrome in Tunisia shows a notable frequency of autosomal recessive forms.
• Absence of Pneumocystis carinii pulmonary infections and sclerosing cholangitis was observed.
• Neurological manifestations occurred in 2 cases, suggesting a distinct clinical profile in this cohort.