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Identification of a High‐Frequency Somatic NLRC4 Mutation as a Cause of Autoinflammation by Pluripotent Cell–Based Phenotype Dissection
Author(s) -
Kawasaki Yuri,
Oda Hirotsugu,
Ito Jun,
Niwa Akira,
Tanaka Takayuki,
Hijikata Atsushi,
Seki Ryosuke,
Nagahashi Ayako,
Osawa Mitsujiro,
Asaka Isao,
Watanabe Akira,
Nishimata Shigeo,
Shirai Tsuyoshi,
Kawashima Hisashi,
Ohara Osamu,
Nakahata Tatsutoshi,
Nishikomori Ryuta,
Heike Toshio,
Saito Megumu K.
Publication year - 2017
Publication title -
arthritis and rheumatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.106
H-Index - 314
eISSN - 2326-5205
pISSN - 2326-5191
DOI - 10.1002/art.39960
Subject(s) - induced pluripotent stem cell , biology , somatic cell , mutation , phenotype , exome , genetics , germline mutation , exome sequencing , gene , embryonic stem cell
Objective To elucidate the genetic background of a patient with neonatal‐onset multisystem inflammatory disease (NOMID) with no NLRP3 mutation. Methods A Japanese male child diagnosed as having NOMID was studied. The patient did not have any NLRP3 mutation, even as low‐frequency mosaicism. We performed whole‐exome sequencing on the patient and his parents. Induced pluripotent stem cells (iPSCs) were established from the patient's fibroblasts. The iPSCs were then differentiated into monocyte lineage to evaluate the cytokine profile. Results We established multiple iPSC clones from a patient with NOMID and incidentally found that the phenotypes of monocytes from iPSC clones were heterogeneous and could be grouped into disease and normal phenotypes. Because each iPSC clone was derived from a single somatic cell, we hypothesized that the patient had somatic mosaicism of an interleukin‐1β–related gene. Whole‐exome sequencing of both representative iPSC clones and the patient's blood revealed a novel heterozygous NLRC4 mutation, p.T177A (c.529A>G), as a specific mutation in diseased iPSC clones. Knockout of the NLRC4 gene using the clustered regularly interspaced short palindromic repeat/Cas9 system in a mutant iPSC clone abrogated the pathogenic phenotype. Conclusion Our findings indicate that the patient has somatic mosaicism of a novel NLRC4 mutation. To our knowledge, this is the first case showing that somatic mutation of NLRC4 causes autoinflammatory symptoms compatible with NOMID. The present study demonstrates the significance of prospective genetic screening combined with iPSC‐based phenotype dissection for individualized diagnoses.