Association of ANCA-associated vasculitis-rheumatoid arthritis overlap syndrome in four patients: rituximab may be the right choice?

OBJECTIVES

There have been few reports on the association of rheumatoid arthritis (RA) with anti-neutrophil cytoplasmic antigen (ANCA)-associated systemic vasculitides.

METHODS

Here we present four cases of RA overlapping with Wegener's granulomatosis (WG), microscopic polyangiitis (MPA) and Churg-Strauss syndrome (CSS). All these cases had both the diagnosis of RA and that of ANCA-associated vasculitis.

RESULTS

After we tried corticosteroids, multiple immunosuppressive drugs, sometimes plasmapheresis, rituximab was introduced to 3 out of 4 cases. Rituximab therapy was found to be effective in these three overlap cases. In the fourth case, rituximab was and will be considered; however, the patient has not given consent.

CONCLUSION

To our knowledge, this is the first report on RA+CSS association. Common pathogenic background, such as genetic predisposition and ANCA may account for the development of RA+vasculitis overlaps. In DMARD-refractory cases, such as the ones presented here, biologics, especially rituximab may be highly effective.

Association of renal ectopia with Fabry's disease in 3 patients

PURPOSE

Fabry's disease is a rare, inherited lysosomal storage disorder characterized by decreased activity of the lysosomal hydrolase alpha-galactosidase A and impaired degradation of globotriaosylceramide, which accumulates in the lysosomes of virtually every cell in the body. Kidney damage is a prominent feature of the disease but to our knowledge renal ectopia as a comorbidity has not been previously reported. We present clinical and genetic features in 2 female and 1 male patient with Fabry's disease and renal ectopia.

MATERIALS AND METHODS

The diagnosis of Fabry's disease was made by measuring alpha-galactosidase A activity in blood leukocytes and by mutational analysis of the alpha-galactosidase A gene. The anatomical location of the kidneys was defined by native and single bolus 3-phase coronal computerized tomography angiography. To determine the possible genetic association of Fabry's disease and renal ectopia we performed a genetic analysis of informative, closely linked microsatellite markers surrounding the gene.

RESULTS

All patients carried the c.469C>T mutation in the alpha-galactosidase A gene, causing premature stop codon (Glu157X). In all 3 patients downward dislocation of the right kidney (pelvic kidney) was found in association with double renal arteries. We noted that a haplotype telomeric to the alpha-galactosidase A gene cosegregated with renal ectopia in 3 family members, suggesting the existence of a gene for X-linked renal ectopia in the region of DXS1001-DXS1073.

CONCLUSIONS

To our knowledge this is the first report of an association of renal ectopia with Fabry's disease.

Novel sequence variants of the alpha-galactosidase A gene in patients with Fabry disease

We carried out molecular studies of 15 unrelated Hungarian families diagnosed with Fabry disease (FD). Genetic analysis of the alpha-galactosidase A gene was performed in 22 hemizygous males and 34 females. One of the female patients with severe disease phenotype showed homozygosity for the recurrent c.644A>G mutation due to parental consanguinity. The c.644A>G mutation that has previously been found mostly in patients with the cardiac variant of FD, was associated with renal but not cardiac involvement in this female and in two other family members. In nine families, eight novel sequence variants such as small deletions (c.363delT, c.477delT, c.746delAC) and single nucleotide changes (c.107T>C, c.493G>C, c.796G>T, c.866T>G, c.871G>A) were found in addition to six previously described private mutations. This report contributes to the identification of novel disease-causing mutations in FD, and increases our knowledge on demographics and molecular characteristics of this rare lysosomal storage disorder. This is the first comprehensive overview of molecular genetic features of Hungarian patients with FD.

Severe Shwachman-Diamond syndrome phenotype caused by compound heterozygous missense mutations in the SBDS gene

OBJECTIVE

A 5-month-old male infant presenting with recurrent respiratory tract infections, chronic diarrhea, and failure to thrive was found to be pancytopenic. Bone marrow and x-ray examinations were consistent with Shwachman-Diamond syndrome (SDS). Genomic DNA sequencing, restriction fragment analysis, and studies of the mutant proteins were performed to gain further knowledge on the molecular pathology of SDS.

MATERIALS AND METHODS

Exons 1 to 5 of the SBDS gene were amplified and sequenced. COS-7 cells were transfected with expression vectors containing wild-type cDNA or mutant cDNAs generated by site-directed mutagenesis. Protein expression of SBDS variants were examined by Western blotting. Pulse-chase assay and densitometry were used to study protein stability.

RESULTS

Two novel missense mutations (c.362A > C in exon 3, and c.523C > T in exon 4) of the SBDS gene were identified in the patient. These mutations result in p.N121T and p.R175W amino acid replacements and correspond to amino acid residues that are highly conserved in SBDS proteins. In vitro expression studies revealed a markedly decreased half-life of the p.R175W protein, whereas stability of the p.N121T mutant was not significantly reduced compared to that of the wild type.

CONCLUSION

This is the first report of compound heterozygous missense mutations occurring in patients with SDS. These mutations may not eliminate SBDS expression but may result in impaired protein stability and protein function leading to severe disease.

Molecular pathology and clinical manifestations of Fabry disease

A Fabry-kór X-kromoszómához kötött öröklődésmenetű, több szervet érintő, ritka, lysosomalis tárolási betegség, amelyet a GAL gén mutációja, az α-galaktozidáz A-enzim elégtelen működése okoz. Az enzimhiány következtében lipid lebontási termékek (glikoszfingolipidek) halmozódnak fel a kiserek endothel sejtjeiben, a simaizomsejtekben, a leukocytákban, és a fibroblastokban. A betegséget a bőrön, a szemben, az idegrendszerben, a vesében és a szívben sokszínű szervi eltérések jellemzik. A Fabry-kór leggyakoribb klinikai megjelenési formái az acroparesthesia, az angiokeratoma, a corneahomály, valamint különféle cardialis, renalis és cerebrovascularis megbetegedések. A 2003 óta Magyarországon is elérhető enzimpótló kezeléssel a betegség progressziója lassítható. A szerzők közleményükben 31 beteg férfi és hordozó nő klinikai adatait foglalják össze. A 31 főből 15 férfi, 16 nő, az elhunytak száma 5 fő (4 férfi, 1 nő). A nők egynegyede tünetmentes. A 7 gondozott család mindegyikében sikerült azonosítani a betegségokozó mutációt; 3 családban új mutáció igazolódott. Enzimpótló kezelésben 12 beteg részesül, közülük 8 férfi, 4 nő.

Characterization of a new disease-causing mutation ofSH2D1Ain a family with X-linked lymphoproliferative disease

Males with an expressed mutation in the SH2D1A gene that encodes an SH2 domain protein named SH2D1A or SAP (NP_002342; signaling lymphocyte activating molecule [SLAM]-associated protein), have an X-linked syndrome characterized by an increased vulnerability to infection with Epstein-Barr virus (EBV). We evaluated two related male patients with fatal infectious mononucleosis (FIM) and mutation in the SH2D1A gene. Sequence analysis revealed a hemizygous c.47G>A mutation in one of the patients, and heterozygosity for this mutation in the genomic DNA from his mother and maternal grandmother. This mutation resulted in p.G16D amino acid change in the sequence of the SAP protein. To analyze the effect of this missense mutation on protein function cDNA was generated by site-directed mutagenesis and expressed in COS cells. We found that half-life of the p.G16D protein was comparable to that of wild type SAP. However, the mutant protein was defective in binding to its physiological ligands SLAM and 2B4. These results suggest that a defect in ligand binding contributes to the loss of function of the SAP protein in patients carrying p.G16D mutation.