Rapid LightCycler assay for identification of the perforin codon 374 Trp --> stop mutation in patients and families with hemophagocytic lymphohistiocytosis (HLH)

BACKGROUND: Recently, point mutations in the Perforin gene on chromosome 10q21 have been described to be the cause of hemophagocytic lymphohistiocytosis (HLH) in a subset of patients. Small deletions, missense, or nonsense mutations were found in both coding exons of the gene. One mutation was found apparently independently in different families of Turkish origin. This Trp374stop mutation is located within a cystein-rich epidermal growth factor (EGF) precursor type domain in exon 3 of the Perforin gene. PROCEDURE: To detect this mutation, we developed a rapid "fluorescence resonance energy transfer" (FRET) assay on the LightCycler based on the different melting behavior of mutated and wild-type sequences. RESULTS: In seven out of 20 analyzed patients with defined HLH history, this Trp374stop mutation was detectable within the different genotypes. Additionally, one out of 90 alleles tested in 45 healthy Turkish controls had this mutation. DISCUSSION: We present a rapid and reliable test for the most common Perforin (Trp374stop) mutation in HLH suitable for genetic testing and prenatal diagnosis. The mutation was detected in a large proportion of Turkish patients. Furthermore, a rapid and precise diagnosis of HLH will shorten the initiation of therapy in this subset of patients.