Our findings broaden the scope of phenotypes caused by mutations in NFKB1 and suggest that a subset of autoinflammatory diseases, such as Behçet disease, can be caused by rare monogenic variants in genes of the NF-κB pathway.
Objective: To determine the proportion of children with herpes simplex encephalitis (HSE) displaying TLR3 deficiency, the extent of TLR3 allelic heterogeneity, and the specific clinical features of TLR3 deficiency.
Methods:We determined the sequence of all exons of TLR3 in 110 of the 120 patients with HSE enrolled in our study who do not carry any of the previously described HSE-predisposing mutations of TLR3 pathway genes (TLR3, UNC93B1, TRIF, TRAF3, and TBK1). All the new mutant TLR3 alleles detected were characterized experimentally in-depth to establish the causal relationship between the genotype and phenotype.Results: In addition to the 3 previously reported TLR3-deficient patients from the same cohort, 6 other children or young adults with HSE carry 1 of 5 unique or extremely rare (minor allele frequency ,0.001) missense TLR3 alleles. Two alleles (M374T, D592N) heterozygous in 3 patients are not deleterious in vitro. The other 3 are deleterious via different mechanisms: G743D1R811I and L360P heterozygous in 2 patients are loss-of-function due to low levels of expression and lack of cleavage, respectively, and R867Q homozygous in 1 patient is hypomorphic. The 3 patients' fibroblasts display impaired TLR3 responses and enhanced herpes simplex virus 1 susceptibility. Overall, TLR3 deficiency is therefore found in 6 (5%) of the 120 patients studied. There is high allelic heterogeneity, with 3 forms of autosomal dominant partial defect by negative dominance or haploinsufficiency, and 2 forms of autosomal recessive defect with complete or partial deficiency. Finally, 4 (66%) of the 6 TLR3-deficient patients had at least 1 late relapse of HSE, whereas relapse occurred in only 12 (10%) of the total cohort of 120 patients.Conclusions: Childhood-onset HSE is due to TLR3 deficiency in a traceable fraction of patients, in particular the ones with HSE recurrence. Mutations in TLR3 and TLR3 pathway genes should be searched and experimentally studied in children with HSE, and patients with proven TLR3 deficiency should be followed carefully. TLR3 is one of the most highly conserved TLRs in humans that have evolved under the strongest purifying selection.1 TLR3 recognizes double-stranded RNA (dsRNA), a by-product produced during the viral replication of most viruses, including herpes simplex virus 1 (HSV-1).2 The most common known clinical consequence of human TLR3 deficiency is childhood herpes simplex encephalitis (HSE). Childhood HSE is a rare life-threatening complication of primary infection with HSV-1, a common neurotropic dsDNA virus that is innocuous in most children.3 HSE is the most common form of sporadic viral encephalitis in Western countries. 4,5 The pathogenesis of HSE had long remained unclear. Our recent studies have demonstrated that HSE may result from singlegene inborn errors of TLR3-mediated immunity in some children, 6 with homozygous or
We describe 3 cases of nephropathia epidemica (NE) that confirm that Puumala virus infection may cause hypophyseal injury. Autopsy revealed a hemorrhagic hypophysis positive for Puumala virus antigen in both neuroendocrine stromal and vascular endothelial cells in 1 patient, and 2 patients developed hypophyseal hemorrhage (diagnosed with magnetic resonance imaging) during or shortly after acute NE, both of whom developed panhypopituitarism.
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