Whole-exome resequencing distinguishes cystic kidney diseases from phenocopies in renal ciliopathies.

Rare single-gene disorders cause chronic disease. However, half of the 6000 recessive single gene causes of disease are still unknown. Because recessive disease genes can illuminate, at least in part, disease pathomechanism, their identification offers direct opportunities for improved clinical management and potentially treatment. Rare diseases comprise the majority of chronic kidney disease (CKD) in children but are notoriously difficult to diagnose. Whole-exome resequencing facilitates identification of recessive disease genes. However, its utility is impeded by the large number of genetic variants detected. We here overcome this limitation by combining homozygosity mapping with whole-exome resequencing in 10 sib pairs with a nephronophthisis-related ciliopathy, which represents the most frequent genetic cause of CKD in the first three decades of life. In 7 of 10 sibships with a histologic or ultrasonographic diagnosis of nephronophthisis-related ciliopathy, we detect the causative gene. In six sibships, we identify mutations of known nephronophthisis-related ciliopathy genes, while in two additional sibships we found mutations in the known CKD-causing genes SLC4A1 and AGXT as phenocopies of nephronophthisis-related ciliopathy. Thus, whole-exome resequencing establishes an efficient, noninvasive approach towards early detection and causation-based diagnosis of rare kidney diseases. This approach can be extended to other rare recessive disorders, thereby providing accurate diagnosis and facilitating the study of disease mechanisms.

Systemic lupus erythematosus with severe nephritis that mimicked Henoch-Schoenlein purpura.

INTRODUCTION: Systemic lupus erythematosus (SLE) belongs to a family of related autoimmune rheumatic disorders that are capable of affecting multiple organs, and they are all associated with a variety of autoantibodies. Henoch Schoenlein purpura (HSP) is a sort of systemic vasculitis that is not associated with auto-antibodies and can affect different organs including the kidneys. CASE REPORT: A 12 year-old girl presented with abdominal pain, low grade fever, swollen and tender feet and left hand, skin rash on the lower extremities, and high blood pressure. Initial laboratory tests revealed severe proteinuria, microscopic hematuria and low C3 level. Renal biopsy showed diffuse proliferative glomerulonephritis with IgA, fibrinogen and C3 deposits. The case was accordingly diagnosed as HSP with severe IgA nephropathy. Treatment was started with mycophenolate mofetil (MMF) and pulse methylprednisolone followed by prednisolone. The patient improved and treatment was discontinued after 5.5 months. One month after withdrawal of her medications, the patient presented again with serositis and recurrent proteinuria. Both antinuclear antibodies (ANA) and anti dsDNA were positive. At this point she was diagnosed to have SLE disease and immunosuppressive treatment was restarted. Following this, symptoms disappeared, proteinuria regressed and anti-dsDNA titer dropped. CONCLUSION: This case presented with features of HSP and was later-on diagnosed to have SLE. This kind of clinical overlapping has not been reported in the literature to the best of our knowledge.

Lupus cystitis in an Omani girl.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple organs involvement. Bladder involvement (Lupus cystitis) is a rare manifestation of SLE, and occurs in association with gastrointestinal manifestations. We report a case of lupus interstitial cystitis with bladder irritation and bilateral hydroureteronephrosis in an adolescent female who was treated with intravenous methylprednisolone pulse therapy followed by oral prednisolone and mycofenolate mofetil (MMF). Her symptoms ameliorated, and the hydroureteronephrosis improved. She was presented again with systemic flare up of the disease together with hydrouretronephrosis, but without bladder irritation symptoms. The diagnosis of lupus cystitis was confirmed by radiographic abnormalities, cystoscopy and bladder biopsy.