Patients with Griscelli syndrome and normal pigmentation identify RAB27A mutations that selectively disrupt MUNC13-4 binding

Valentina Cetica, Yvonne Hackmann, Samantha Grieve, Elena Sieni, Benedetta Ciambotti, Maria Luisa Coniglio, Daniela Pende, Kimberly Gilmour, Paolo Romagnoli, Gillian M. Griffiths, Maurizio Aricò

Research output: Contribution to journalArticlepeer-review


Background Familial hemophagocytic lymphohistiocytosis (FHL) is a rare and often fatal disorder characterized by defective cellular cytotoxicity and hyperinflammation, and the only cure known to date is hematopoietic stem cell transplantation. Mutations in RAB27A, LYST, and AP3B1 give rise to FHL associated with oculocutaneous albinism, and patients with FHL are usually only screened for mutations in these genes when albinism is observed. A number of patients with FHL and normal pigmentation remain without a genetic diagnosis. Objective We asked whether patients with FHL with immunodeficiency but with normal pigmentation might sometimes have mutations that affected cellular cytotoxicity without affecting pigmentation. Methods We carried out mutation analysis of RAB27A, LYST, and AP3B1 in patients with FHL with pigment dilution, as well as a cohort with no clinical evidence of pigment dilution but no mutations in the other known FHL-related genes (PRF1, STXBP2, and UNC13D). Results We identify patients with Griscelli syndrome type 2 with biallelic mutations in RAB27A in the absence of albinism. All 6 patients carried mutations at amino acids R141, Y159, or S163 of Rab27a that disrupt the interaction of Rab27a with Munc13-4, without impairing the interaction between melanophilin and Rab27a. Conclusion These studies highlight the need for RAB27A sequencing in patients with FHL with normal pigmentation and identify a critical binding site for Munc13-4 on Rab27a, revealing the molecular basis of this interaction.

Original languageEnglish
Pages (from-to)1310-1318e1
JournalJournal of Allergy and Clinical Immunology
Issue number5
Publication statusPublished - May 1 2015


  • cytotoxic T lymphocyte
  • familial hemophagocytic lymphohistiocytosis
  • Griscelli syndrome type 2
  • Hemophagocytic lymphohistiocytosis
  • melanophilin
  • natural killer cells

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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