NBAS, a gene involved in cytotoxic degranulation, is recurrently mutated in pediatric hemophagocytic lymphohistiocytosis

Xiaoman Bi, Qing Zhang, Lei Chen, Dan Liu, Yueying Li, Xiaoxi Zhao, Ya Zhang, Liping Zhang, Jingkun Liu, Chaoyi Wu, Zhigang Li, Yunze Zhao, Honghao Ma, Gang Huang, Xin Liu, Qian fei Wang, Rui Zhang

Research output: Contribution to journalLetterpeer-review

Abstract

Hemophagocytic lymphohistiocytosis (HLH), particularly primary HLH (pHLH), is a rare, life-threatening disease. Germline genetic deficiency of 12 known HLH genes impairs cytotoxic degranulation in natural killer (NK) cells or cytotoxic T lymphocytes (CTLs) and contributes to pHLH development. However, no pathogenic mutations in these HLH genes are found in nearly 10% of HLH patients, despite a strong suspicion of pHLH, suggesting that the underlying genetic basis of HLH is still unclear. To discover novel susceptibility genes, we first selected 13 children with ppHLH (presumed primary HLH patients in the absence of detectable known HLH gene variants) and their parents for initial screening. Whole-genome sequencing (WGS) in one trio and whole-exome sequencing (WES) in twelve trios revealed that two ppHLH patients carried biallelic NBAS variants, a gene that is involved in Golgi-to-endoplasmic reticulum (ER) retrograde transport upstream of the degranulation pathway. Additionally, two candidate genes, RAB9B and KLC3, showed a direct relationship with known HLH genes in protein-protein interaction (PPI) network analysis. We analyzed NBAS, RAB9B, KLC3 and known HLH genes in an independent validation cohort of 224 pediatric HLH patients. Only biallelic NBAS variants were identified in three patients who harbored no pathogenic variants in any of the known HLH genes. Functionally, impaired NK-cell cytotoxicity and degranulation were revealed in both NBAS biallelic variant patients and in an NBAS-deficient NK-cell line. Knockdown of NBAS in an NK-cell line (IMC-1) using short hairpin RNA (shRNA) resulted in loss of lytic granule polarization and a decreased number of cytotoxic vesicles near the Golgi apparatus. According to our findings, NBAS is the second most frequently mutated gene (2.11%) in our HLH cohort after PRF1. NBAS deficiency may contribute to the development of HLH via a dysregulated lytic vesicle transport pathway.

Original languageEnglish (US)
Article number101
JournalJournal of Hematology and Oncology
Volume15
Issue number1
DOIs
StatePublished - Dec 2022
Externally publishedYes

Keywords

  • Germline variants
  • Hemophagocytic lymphohistiocytosis
  • NBAS
  • NK-cell
  • Trios

ASJC Scopus subject areas

  • Molecular Biology
  • Hematology
  • Oncology
  • Cancer Research

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