CARD9 Deficiency Mimicking Hyper-IgE Syndrome
Caspase recruitment domain-containing protein 9 (CARD9) deficiency is a rare primary immunodeficiency characterized by a profound susceptibility to invasive fungal infections. Given its significant phenotypic overlap with hyper-IgE syndrome (HIES)—most notably, markedly elevated serum IgE levels—misdiagnosis remains...