title: A novel pathogenic variant in PRF1 associated with hemophagocytic lymphohistiocytosis.
abstract: Familial Hemophagocytic Lymphohistiocytosis type 2 (FHL2) results from mutations in PRF1. We described two unrelated individuals who presented with FHL, in whom severely impaired NK cytotoxicity and decrease perforin expression was observed. DNA sequencing of PRF1 demonstrated that both were not only heterozygous for the p.54R > C/91A > V haplotype but also presented with the novel variant p.47G > V at the perforin protein. Perforin mRNA was found to be increased in a individual with that genotype. A carrier of the novel variant also demonstrated altered perforin mRNA and protein expression. Phylogenetic analysis and multiple alignments with perforin orthologous demonstrated a high level of conservation at Gly47. PolyPhen-2 and PROVEAN predicted p.47G > V to be "probably damaging" and "deleterious", respectively. A thermodynamic analysis showed that this variant was highly stabilizing, decreasing the protein internal energy. The ab initio perforin molecular modeling indicated that Gly47 is buried inside the hydrophobic core of the MACPF domain, which is crucial for the lytic pore formation and protein oligomerization. After the in silico induction of the p.47G > V mutation, Val47 increased the interactions with the surrounding amino acids due to its size and physical properties, avoiding a proper conformational change of the domain. To our knowledge, this is the first description supporting that p.47G > V is a pathogenic variant that in conjunction with p.54R > C/91A > V might result in the clinical phenotype of FHL2.
authors.affiliation: Grupo de Inmunodeficiencias Primarias, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia.
authors.forename: Camilo Andrés Pérez
authors.initials: CA
authors.lastname: Romero
authors.forename: Isaura Pilar
authors.initials: IP
authors.lastname: Sánchez
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gutierrez-Hincapié
authors.forename: Jesús A
authors.initials: JA
authors.lastname: Álvarez-Álvarez
authors.forename: Jaime Andres
authors.initials: JA
authors.lastname: Pereañez
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Ochoa
authors.forename: Carlos Enrique
authors.initials: CE
authors.lastname: Muskus-López
authors.forename: Ruth G
authors.initials: RG
authors.lastname: Eraso
authors.forename: Carolina
authors.initials: C
authors.lastname: Echeverry
authors.forename: Catalina
authors.initials: C
authors.lastname: Arango
authors.forename: José Luis Franco
authors.initials: JL
authors.lastname: Restrepo
authors.forename: Claudia Milena
authors.initials: CM
authors.lastname: Trujillo-Vargas
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D019295:Computational Biology; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D015536:Down-Regulation; D005260:Female; D006801:Humans; D007223:Infant; D007694:Killer Cells, Natural / Q000502:physiology*; D051359:Lymphohistiocytosis, Hemophagocytic / Q000175:diagnosis* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D010375:Pedigree; D054353:Perforin / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D055815:Young Adult
chemical_list: C510468:PRF1 protein, human; D054353:Perforin