Three Consecutive Cases of Familial Hemophagocytic Lymphohistiocytosis, Including a Case Due to Maternal Uniparental Disomy.

We have experienced 3 consecutive cases of familial hemophagocytic lymphohistiocytosis (FHL). All affected infants had mutations in exon 3 of the perforin gene. The first had a homozygous mutation, c.1168C>T (p.R390*), caused by maternal uniparental isodisomy. The second and third had compound heterozygous mutations: c.781G>A (p.E261K) and c.1491T>A (p.C497*); c.1724G>T (p.C242G) and p.R390*, respectively. FHL is very rare in Northern Japan but should be suspected if infants exhibit prolonged fever. This is the first report of a relationship of p.R390* with FHL caused by uniparental isodisomy, and the second reported case of FHL type 2 with this form of inheritance.