Familial Hemophagocytic Lymphohistiocytosis type 3 (FHL3) is a genetic disorder caused by mutations in UNC13D gene, coding the granule priming factor Munc13-4 that intervenes in NK and T cell cytotoxic function. Here we report the case of a 17-month-old girl with prolonged symptomatic EBV infectious mononucleosis and clinical symptoms of hemophagocytic syndrome. In vitro functional analysis pointed to a degranulation defect. The genetic analysis of UNC13D gene identified initially a heterozygous mutation (c.753 + 1G > T) in the donor splice-site that resulted in exon 9 skipping (maternal allele). Mutations in other genes were considered, but additional analysis of UNC13D cDNA revealed in the paternal allele a heterozygous transition from G to A (c.2448 - 13G > A) at the 3' acceptor splice-site in intron 25, generating a new acceptor splice-site that leads to a frameshift and a premature STOP codon. Allele specific amplification of the cDNA confirmed the absence of a functional mRNA from the paternal allele. This case illustrates an atypical compound heterozygous UNC13D mutation affecting the RNA splicing that generates a typical FHL3 phenotype. © 2014 Elsevier Inc.
- Degranulation defect
- Familial Hemophagocytic Lymphohistiocytosis type 3 (FHL3)
- RNA splicing defects
- UNC13D gene
Alsina, L., Colobran, R., De Sevilla, M. F., Català, A., Viñas, L., Ricart, S., Plaza, A. M., Lois, S., Juan, M., Pujol-Borrell, R., & Martinez-Gallo, M. (2014). Novel and atypical splicing mutation in a compound heterozygous UNC13D defect presenting in Familial Hemophagocytic Lymphohistiocytosis triggered by EBV infection. Clinical Immunology, 153(2), 292-297. https://doi.org/10.1016/j.clim.2014.04.019