Hyper IgM Syndrome with low IgM and thrombocytosis: an unusual case of immunodeficiency

Area of Science:

• Immunology
• Genetics
• Pediatrics

Background:

• Hyper-IgM syndrome (HIGM) is a group of primary immunodeficiencies characterized by defects in immunoglobulin class switching.
• X-linked hyper-IgM syndrome (X-HIGM) specifically results from mutations in the CD40 ligand (CD40L) gene.

Observation:

• A 5-year-old male presented with recurrent oral and perianal ulcers, intermittent fever, and chronic diarrhea.
• Despite the absence of typical respiratory infections, laboratory findings included low serum IgG, IgA, and IgM levels, along with persistent thrombocytosis.

Findings:

• The clinical presentation and laboratory results led to the consideration of X-linked hyper-IgM syndrome (X-HIGM).
• Genetic testing confirmed a diagnosis of hyper-IgM syndrome due to CD40L deficiency.

Implications:

• This case highlights the diverse clinical manifestations of CD40L deficiency, emphasizing the importance of considering X-HIGM even without classic respiratory symptoms.
• Accurate diagnosis of CD40L deficiency is crucial for appropriate management and genetic counseling.
• Understanding the role of CD40L in B-cell maturation and immune regulation is vital for developing targeted therapies.