ITK Gene Mutation: Effect on Survival of Children with Severe Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is characterized by deadly hyperinflammatory syndrome, but data on severe HLH with multi-organ dysfunction in children are scant. The authors report a retrospective study of 8 cases with severe HLH from a pediatric intensive care unit (PICU) over a 1-y period and found that Epstein barr virus (EBV) -infection was the most common etiology. All patients had genetic analysis, which showed that four patients with EBV -infection had one homozygous mutation, c.985+75G>A (at position chr5:156667232) in exon10 of the ITK gene with poor survival rates. ITK + mutation group had higher percentages of CD3+ CD8+ T cells (36.0 ± 8.4 %) than those in ITK - mutation group (28.8 ± 5.5 %), while they had similar levels of CD3+ CD4+ T cells. ITK + mutation group had lower proportion of CD3- CD19+ B cells (16.3 ± 2.9 %) and CD16+ CD56+ NK cells (8.4 ± 2.6 %) than ITK - mutation group (29.6 ± 5.1 % and 15.9 ± 9.0 % respectively). Most importantly, patients with EBV infection with c.985+75G>A mutation in ITK had lower survival rates than ITK - mutation group which it may be related with cellular immune dysfunction.