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OBJECTIVE: To describe biochemical findings and the spectrum of mevalonate kinase (MVK) gene mutations as well as an associated TNFRSF1A low-penetrance variant in a series of patients with clinical features of the hyperimmunoglobulinemia D with periodic fever syndrome (HIDS). METHODS: The MVK gene was sequenced in 8 children and 1 adult (including 2 siblings) fulfilling the clinical criteria for HIDS. In addition, sequencing of exons 2, 3, 4, and 6 of the TNFRSF1A gene was performed in patients with only one or no MVK mutation. Mevalonate kinase (MK) enzyme activity in leukocytes and renal excretion of mevalonic acid were also measured. RESULTS: Mutations in the coding region of the MVK gene were detected in 6 patients, and the most common mutation was V377I. Among these patients were 2 novel mutations, both of which were located in exon 6. These novel mutations resulted in the substitution of tryptophan (TGG) by a stop codon (TGA) at amino acid position 188 (W188X) and in the exchange of valine (GTG) for alanine (GCG) at amino acid position 203 (V203A). In 1 patient, a combination of one MVK (V377I) mutation and one TNFRSF1A (R92Q) mutation was present. The patient's clinical phenotype resembled a mixture of variant-type HIDS and tumor necrosis factor receptor-associated periodic syndrome (TRAPS). Her IgD values varied between normal and slightly increased, and the MK activity was in the low-normal range, while urinary mevalonate concentrations were always normal. CONCLUSION: The genotype findings indicate that a relatively small number of genes may be involved in the clinical manifestation of HIDS, with low-penetrance TNFRSF1A variants possibly influencing the HIDS phenotype or MVK mutations contributing to TRAPS. [ABSTRACT FROM AUTHOR]

PFAPA syndrome is characterized by periodic episodes of high fever, aphthous stomatitis, pharyngitis, and/or cervical adenitis. It is of unknown etiology and manifests usually before 5 years of age. We determined serum and intracellular cytokine levels in six PFAPA patients (4 males, 2 females, mean age 8 years (+/- 1.2 SEM), range 4-13) during the symptom-free period as well as 6-12 hours and 18-24 hours after fever onset. Values were compared to age-matched, healthy controls. Febrile PFAPA attacks led to a significant increase in IL-6 and IFN-gamma serum concentrations compared to symptom-free periods and to controls, with IL-1beta, TNF-alpha and IL-12p70 levels being significantly higher than in controls. Lymphocytic IFN-gamma and CD8+ IL-2 production was consistently significantly elevated compared to healthy children. During the asymptomatic period, serum concentrations of IL-1beta, IL-6, TNF-alpha and IL-12p70 were significantly increased compared to controls. Intracellular TNF-alpha synthesis was not elevated at any time point. Soluble TNFRp55 levels were even lower in between febrile episodes, reaching values comparable to controls during attacks, whereas soluble TNFRp75 levels increased during attacks compared to healthy children. Anti-inflammatory IL-4 in serum was at all times lower in PFAPA patients compared to controls with no difference in levels of intracellular IL-4 and IL-10 or serum IL-10. The observed increase of pro-inflammatory mediators, even between febrile attacks, suggests a dysregulation of the immune response in PFAPA syndrome, with continuous pro-inflammatory cytokine activation and a reduced anti-inflammatory response.

The hyperimmunoglobulinemia D and periodic fever syndrome (HIDS) is an autosomal recessively inherited autoinflammatory disease caused by mutations in the mevalonate kinase (MVK) gene on chromosome 12q24, which lead to a depressed enzymatic activity of mevalonate kinase (MK). TNF-receptor associated periodic syndrome (TRAPS), on the other hand, is the most frequent autosomal dominantly inherited periodic fever syndrome due to mutations in exons 2-4 and 6 of the TNFRSF1A gene on chromosome 12p13.2. We describe a girl with heterozygosity for the common MVK V377I mutation and for a novel T(1132) --> C transition, leading to the exchange of serine (TCC) by proline (CCC) at amino-acid position 378. Interestingly, our patient presented only with mild clinical features typical of HIDS and slightly increased immunoglobulin D levels, but a distinctly diminished MK activity. The girl was also heterozygous for the TNFRSF1A R92Q low-penetrance mutation, which may have significant proinflammatory effects. However, at the time of presentation, the patient had no TRAPS-associated symptoms.