Occurrence of arthritis in hyperimmunoglobulinaemia D

Establishment of a transgenic mouse model with liver-specific expression of secretory immunoglobulin D

Mutation of mevalonate kinase (MVK) is thought to account for most cases of hyperimmunoglobulinemia D syndrome (HIDS) with recurrent fever. However, its mechanism and the relationship between elevated serum immunoglobulin D (IgD) and the clinical features of HIDS are unclear. In this study, we generated by fusion PCR a vector to express high levels of chimeric secretory IgD (csIgD) specifically in the liver. We then generated seven founder lines of transgenic mice by co-microinjection, and verified them using genomic PCR and Southern blotting. We detected the expression of csIgD by reverse transcription PCR, quantitative PCR, western blotting, and enzyme-linked immunosorbent assays. We demonstrated that csIgD could be specifically and stably expressed in the liver. We used flow cytometry to show that overexpression of csIgD in the bone marrow and spleen cells had no effect on B cell development. Morphologic and anatomical observation of the transgenic mice revealed skin damage, hepatosplenomegaly, and nephromegaly in some transgenic mice; in these mice, pathological sections showed high levels of cell necrosis and protein-like sediments in the liver, spleen, and kidney. We demonstrated that the genomic insertion sites of the transgenes did not disrupt the MVK gene on mouse chromosome 5. This transgenic mouse will be useful to explore the pathogenesis of HIDS.

B cell cytopenia in two brothers with hyper-IgD and periodic fever syndrome

We report on two brothers with hyperimmunoglobulinemia D (patient 1: serum immunoglobulin D [IgD] concentration initially 61 IU/ml, later on 340 IU/ml; patient 2: serum IgD concentration 144 IU/ml; normal <100 IU/ml, 97th centile) and periodic fever syndrome (HIDS). Both are compound heterozygous for the mevalonate kinase (MVK) mutations V377I and I268T. They developed significant B cell cytopenia (7%, 129/microl and 11%, 132/microl, respectively; normal ranges 12-22%, 300-500/microl) with hypogammaglobulinemia (IgG 5.48 g/l and IgG 5.22 g/l, respectively; normal range IgG 6-13 g/l). Furthermore, the clinical spectrum shows an interesting atypical autoinflammatory symptomatology. The therapy consisted of prednisone, azathioprine, and intravenous immunoglobulins (IVIG), which results in reduced incidence and severity of febrile attacks.

CONCLUSION

The pathogenesis and clinical presentation of HIDS is still not fully understood and show a great variability. To our knowledge, severe B cell cytopenia in children with HIDS has not been reported before. Furthermore, the therapy of febrile episodes is still performed on an individual basis in affected patients.

Hyper-immunoglobulin A in the hyperimmunoglobulinemia D syndrome

The hyperimmunoglobulinemia D syndrome (HIDS) is an autosomal recessive disorder characterized by recurrent febrile attacks with abdominal, articular, and skin manifestations. Apart from elevated immunoglobulin D (IgD) levels (>100 IU/ml), there are high IgA levels in the majority of cases. Mutations in the gene encoding mevalonate kinase constitute the molecular defect in HIDS. The cause of elevated IgA concentrations in HIDS patients remains to be elucidated. We studied the hyper-IgA response in serum of a group of HIDS patients. Elevated IgA concentrations result from increased IgA1 concentrations. IgA and IgA1 concentrations correlated significantly with IgD concentrations, and levels of IgA polymers were significantly higher than the levels in healthy donors. These results indicate a continuous, presumably systemic, stimulation of IgA in HIDS patients.

Atypical hypergammaglobulinaemia D syndrome with amyloidosis: an overlap with familial Mediterranean fever?

A case of hypergammaglobulinaemia D and periodic fever syndrome, developing an amyloidosis-related nephrotic syndrome, is reported. Since such a complication represents a typical feature of another disease characterized by recurrent febrile attacks, i.e., familial Mediterranean fever, an overlap syndrome between these two rare clinical disorders can be suggested.