Hatem El-Shanti

An Autoinflammatory Disease with Deficiency of the Interleukin-1–Receptor Antagonist

BACKGROUND Autoinflammatory diseases manifest inflammation without evidence of infection, high-titer autoantibodies, or autoreactive T cells. We report a disorder caused by mutations of IL1RN, which encodes the interleukin-1-receptor antagonist, with prominent involvement of skin and bone. METHODS We studied nine children from six families who had neonatal onset of sterile multifocal osteomyelitis, periostitis, and pustulosis. Response to empirical treatment with the recombinant interleukin-1-receptor antagonist anakinra in the first patient prompted us to test for the presence of mutations and changes in proteins and their function in interleukin-1-pathway genes including IL1RN. RESULTS We identified homozygous mutations of IL1RN in nine affected children, from one family from Newfoundland, Canada, three families from The Netherlands, and one consanguineous family from Lebanon. A nonconsanguineous patient from Puerto Rico was homozygous for a genomic deletion that includes IL1RN and five other interleukin-1-family members. At least three of the mutations are founder mutations; heterozygous carriers were asymptomatic, with no cytokine abnormalities in vitro. The IL1RN mutations resulted in a truncated protein that is not secreted, thereby rendering cells hyperresponsive to interleukin-1beta stimulation. Patients treated with anakinra responded rapidly. CONCLUSIONS We propose the term deficiency of the interleukin-1-receptor antagonist, or DIRA, to denote this autosomal recessive autoinflammatory disease caused by mutations affecting IL1RN. The absence of interleukin-1-receptor antagonist allows unopposed action of interleukin-1, resulting in life-threatening systemic inflammation with skin and bone involvement. (ClinicalTrials.gov number, NCT00059748.)

Mutations in the CCN gene family member WISP3 cause progressive pseudorheumatoid dysplasia

Members of the CCN (for CTGF, cyr61/cef10, nov) gene family encode cysteine-rich secreted proteins with roles in cell growth and differentiation. Cell-specific and tissue-specific differences in the expression and function of different CCN family members suggest they have non-redundant roles. Using a positional-candidate approach, we found that mutations in the CCN family member WISP3 are associated with the autosomal recessive skeletal disorder progressive pseudorheumatoid dysplasia (PPD; MIM 208230). PPD is an autosomal recessive disorder that may be initially misdiagnosed as juvenile rheumatoid arthritis. Its population incidence has been estimated at 1 per million in the United Kingdom, but it is likely to be higher in the Middle East and Gulf States. Affected individuals are asymptomatic in early childhood. Signs and symptoms of disease typically develop between three and eight years of age. Clinically and radiographically, patients experience continued cartilage loss and destructive bone changes as they age, in several instances necessitating joint replacement surgery by the third decade of life. Extraskeletal manifestations have not been reported in PPD. Cartilage appears to be the primary affected tissue, and in one patient, a biopsy of the iliac crest revealed abnormal nests of chondrocytes and loss of normal cell columnar organization in growth zones. We have identified nine different WISP3 mutations in unrelated, affected individuals, indicating that the gene is essential for normal post-natal skeletal growth and cartilage homeostasis.

Autoinflammatory bone disorders.

Purpose of reviewThis review provides an update on clinical, genetic, and immunologic aspects of the autoinflammatory bone disorders. Recent findingsChronic noninfectious inflammation of the bone is a clinical feature of both chronic recurrent multifocal osteomyelitis and (to a lesser degree) cherubism. The genes responsible for Majeed syndrome (LPIN2), murine chronic multifocal osteomyelitis (pstpip2), and cherubism (SH3BP2 and possibly PTPN11) have been identified. Murine models of both chronic recurrent multifocal osteomyelitis and cherubism have demonstrated that the bone inflammation is mediated by hematopoietically derived cells and can occur in the absence of a functioning adaptive immune system. As the immunologic defects become better defined, the cells of the myeloid lineage are emerging as the primary players. SummaryChronic multifocal osteomyelitis and cherubism are hereditary chronic inflammatory disorders in which bone is the primary inflammatory target. Recent genetic and immunologic discoveries demonstrate involvement of the innate immune system, which places these entities in the category of autoinflammatory disorders.

Spectrum of mutations and carrier frequency of familial Mediterranean fever gene in the Algerian population

OBJECTIVES FMF is characterized by recurrent self-limiting episodes of fever and painful polyserositis. We aimed to study the spectrum and distribution of MEFV mutations in an Algerian patient cohort using a comprehensive mutation detection method. Using the same methodology, we also studied the carrier rate in an unaffected ethnically matched control cohort. METHODS We recruited 71 unrelated subjects clinically diagnosed with FMF from various clinics in the central region of Algeria. Two hundred and thirty control subjects were recruited as well. Mutation detection in MEFV was performed by re-sequencing the promoter region, the entire coding sequence and all exon-intron boundaries. RESULTS We detected eight different mutations located in exons 10 (p.M694I, p.M694V, p.A744S, p.M680I, p.I692Del), 9 (p.I591T), 3 (p.P369S/p.R408Q) and 2 (p.E148Q). Out of the 71 patients, 31 carried at least one mutation. While the 71 patients are expected to have 142 mutant chromosomes, only 50 were identified. p.M694I (17.6%) is the most common mutation, followed by p.M694V (5%), p.E148Q (4.2%), p.A744S (3.5%) and p.M680I (3%). One novel variant was identified in the promoter region in the heterozygous state in three patients and in two controls. The carrier rate of the identifiable mutations is estimated to be 1 : 5. CONCLUSION This study describes the MEFV mutational spectrum and distribution in the Algerian population. It shows that p.M694I is the most common MEFV mutation in Algerians. It also shows that, similar to other Arabic populations, <50% of mutant chromosomes are identified, even when employing comprehensive strategies.