Familial Hemophagocytic Lymphohistiocytosis: A Rare Mutation of STXBP2 in Exon 19

Familial hemophagocytic lymphohistiocytosis (FHLH) is a fulminant rapidly progressive disorder characterized by uncontrolled immune system activation. Over the last decade, STXBP2 mutations have been reported as causative. We report a baby with typical clinical features and supportive laboratory findings, who had a homozygous missense variation in exon 19 of STXBP2 that results in an amino acid substitution of aspartic acid for glycine. Adding to the currently scant literature on this variation may contribute to the database pool and help to confirm assertion of pathogenicity in FHLH.