STX11 mutations and clinical phenotypes of familial hemophagocytic lymphohistiocytosis in North America.

Background: Mutations in STX11 are responsible for Familial Hemophagocytic Lymphohistiocytosis (FHLH) type 4, a rare primary immunodeficiency which has previously been observed only in patients of Kurdish, Turkish, and Lebanese ethnic background.

Methods: We reviewed our experience with STX11 mutations among North American patients and studied the impact of patient mutations upon syntaxin 11 expression and NK cell function.

Results: Between 2007 and 2008, 243 patients with HLH (lacking disease-causing mutations in PRF1 and UNC13D) were referred for STX11 mutational analysis.

Macrophage activation syndrome in patients with systemic juvenile idiopathic arthritis is associated with MUNC13-4 polymorphisms.

Objective: Systemic juvenile idiopathic arthritis (JIA) is associated with macrophage activation syndrome. Macrophage activation syndrome bears a close resemblance to familial hemophagocytic lymphohistiocytosis (HLH). The development of familial HLH has been recently associated with mutations in MUNC13-4.