[Analysis of PRF1gene variant in a child with late-onset familial hemophagocytic lymphohistiocytosis type 2 and severe central nervous system disease]

Abstract

Objective: To detect genetic mutations in a child with late-onset hemophagocytic lymphohistiocytosis (HLH).

Methods: Clinical data of an 8-year-5-month-old girl with recurrent HLH and severe central nervous system disease was analyzed. Next-generation sequencing was used to detect mutation in the exons and adjacent introns of 17 genes associated with HLH. Suspected mutations were confirmed by Sanger sequencing. Influence of mutations on protein function was predicted with SIFT and PolyPhen-2 software.

Results: The child was found to carry compound heterozygous mutations of the PRF1 gene. Among these, the c.1349C>T (p.Thr450Met) mutation, with a SIFT predictive value of -4.921 (Deleterious variant) and a PolyPhen-2 predictive value of 1.000 (Probably damaging), was inherited from her father and known to be pathogenic. The c.1273dupT (p.Trp425fsX457) mutation was inherited from her mother and previously unreported, which resulted in the deletion of almost the entire C2 domain (amino acid residues 413 to 540) and carboxyl terminal of perforin, which seriously affected the function of the protein.

Conclusion: The c.1349C>T (p.Thr450Met) and c.1273 dupT (p.Trp425fsX457) compound heterozygous mutations of the PRF1 gene probably underlie the disease in this patient.