NLRP3-associated autoinflammatory diseases: Phenotypic and molecular characteristics of germline versus somatic mutations

Abstract

Background: NLRP3-associated autoinflammatory diseases (NLRP3-AIDs) include conditions of various severities, due to germline or somatic mosaic NLRP3 mutations. Objective: To identify mosaic-versus germline-specific NLRP3 mutations' characteristics, we reinterpreted all the mutations reported in NLRP3-AIDs and performed an in-depth study of 3 novel patients. Methods: The pathogenicity of all reported mosaic/germline mutations was reassessed according to international recommendations and their location on the NLRP3 3dimensional structure. Deep-targeted sequencing and NLRP3inflammasome-activation assays were used to identify the disease-causing mutation in 3 patients. Results: We identified, in 3 patients, mosaic mutations affecting the same NLRP3 amino acid (Glu569). This residue belongs to 1 of the 2 mosaic mutational hot spots that face each other in the core of the NLRP3 ATPase domain. The review of the 90 NLRP3 mutations identified in 277 patients revealed that those hot spots account for 68.5% of patients (37 of 54) with mosaic mutations. Glu569 is affected in 22% of the patients (12 of 54) with mosaic mutations and in 0.4% of patients (1 of 223) with germline mutations. Only 8 of 90 mutations were found in mosaic and germinal states. All of the germline mutations were associated with a severe phenotype. These data suggest that mutations found only in mosaic state could be incompatible with life if present in germinal state. None of the 5 most frequent germline mutations was identified in mosaic state. Mutations found only in germinal state could, therefore, be asymptomatic in mosaic state. Conclusions: The phenotypic spectrum of NLRP3-AIDs appears to be related to the germinal/mosaic status and localization of the underlying mutations.

Computational Modeling of NLRP3 Identifies Enhanced ATP Binding and Multimerization in Cryopyrin-Associated Periodic Syndromes

“…However, they differed in the WHD subdomain: FCAS and MWS, which are the hereditary and milder CAPS, have a higher proportion of mutations within the WHD subdomain than CINCA/NOMID. Consistent with other studies (136)(137)(138), somatic mosaic mutations occur mostly in the NBD and HD2 subdomains ( Figure 1E). We confirmed two previously-reported mutational hotspots in the NBD subdomain between Gly303 to Gly309 and within the HD2 domain (136) and identified a third mutational hotspot that straddles the HD1 and WHD subdomains (boxed areas, Supplementary Figure 1A).…”

“…Consistent with other studies (136)(137)(138), somatic mosaic mutations occur mostly in the NBD and HD2 subdomains ( Figure 1E). We confirmed two previously-reported mutational hotspots in the NBD subdomain between Gly303 to Gly309 and within the HD2 domain (136) and identified a third mutational hotspot that straddles the HD1 and WHD subdomains (boxed areas, Supplementary Figure 1A). Due to fewer non-CAPS NLRP3-AID reports, we were unable to determine whether these NLRP3-AIDs had unique mutational hotspots or domain mutational enrichments of significance ( Supplementary Figures 1B-E).…”

“…As observed in other studies (136,141), we found that mutations with the lowest p-weighted scores (log(p w ) < −2, corresponding to p w < 0.01), which are expected to be the most severely-disruptive to NLRP3 structure and function, occur in the NACHT domain between Glu250 and Arg550 with a mutational hotspot including the Arg262 site ( Figure 2A). Arg262 is the most cited mutation site (17, 59-61, 64, 66, 69, 93, 96, 136), is shared between all CAPS, and has a wide variance of reported substitutions.…”

“…Supplementary Figure 1) and analyzed the proportion of mutations between all NLRP3-AIDs ( Figure 1E). We confirmed the high frequency of mutation, 83% (147/177 mutations), in NACHT ( Figure 1A) (136,137). In all three CAPS, we found two shared mutational hotspots: the first between the Walker A and Walker B motifs from Cys261 and Thr268, and the second within the WHD between Asn479 to Glu527 (hotspots 1 and 2, Figures 1B-D).…”

Familial Mediterranean Fever and COVID-19: Friends or Foes?

“…In addition, differently from MEFV, the most common human NLRP3 mutations-R260W, D303N, T348M, and L355P-which represent more than 40% of the total mutation burden for this gene (53,54), were never present as wild type amino acid residues in all bat species and pangolin ( Figure 5).…”