To the editor: IgA nephropathy is the most common chronic primary glomerulonephritis, leading to progressive renal failure in at least one third of patients.1 No association of this disease with the lupus anticoagulant (LA) has been found in the literature. The occurrence of IgA nephropathy in two sisters, one of whom had LA, is reported.



CASE 1



A 26-year-old female patient with a history of acne and recurrent urinary tract infection. She was studied for

gross hematuria after upper respiratory tract infections. Physical examination was normal. Laboratory test results

included: creatinine 1.4 mg/dL, hematocrit 25%, prothrombin activity 87%, APTT 44.7 seconds , fibrinogen

434 mg/dL. Immunological test results included: IgG 1260 mg/dL (N: 751-1560), IgA 667 mg/dL (N:82-453),

IgM 190 mg/dL (N: 46-304), C3 88 mg/dl (N: 79-152), C4 27.8 mg/dl (N: 16- 38), negative ANA. Urine sediment

showed 6-10 RBCs/field. Proteinuria in a 24-hour sample was 3 g/day. A renal pathology study confirmed the

existence of IgA nephropathy. As the patient had a prolonged cephalin time, a hypercoagulability study was performed, showing a positive result for IgM anticardiolipin antibodies, 50.7 MPL/mL (N < 11).



CASE 2



A 29-year-old female patient with personal and clinical history similar to her sister (case 1). Physical examination

was normal. Results of laboratory blood tests included: Creatinine 1 mg/dL. Normal complete blood count. Coagulation: Prothrombin activity 84%, APTT 39.5 sec. Negative LA and anticardiolipin antibodies. Immunological

tests showed the following values: IgG 1470 mg/dL, IgA 388 mg/dL, IgM 417 mg/dL, C3 100 mg/dL, C4 28.6 mg/dL. ASLO, ANA, and anti-DNA antibodies were negative. Urine sediment showed more than 40 RBCs/field. No protein

was found in a 24-hour urine sample. Renal biopsy confirmed the existence of nephropathy with IgA mesangial

deposits.



DISCUSSION



IgA nephropathy is characterized by IgA mesangial deposits associated to a proliferative mesangial glomerulonephritis. Its pathogenesis is not fully known, but there is increasing evidence of the formation of immune complexes containing IgA that would be deposited in mesangium and would induce glomerular damage.2



The primary antiphospholipid syndrome (PAPS) is characterized by recurrent thrombosis, multiorgan damage, and abortion, as well as the presence of LA and/or anticardiolipin antibodies.



LAs are antibodies directed against plasma proteins such as b2-glycoprotein I, prothrombin, or annexin V.3,4 In

case 1, a basic coagulation study detected a prolonged cephalin time, and a subsequent hypercoagulability study

was positive for LA anticardiolipin antibodies, but there were no associated clinical signs consistent with PAPS.



Association of LA and anticardiolipin antibodies with various autoimmune and rheumatic diseases (SLE, scleroderma, psoriatic arthritis¿) has been reported in the literature,5 but there are no reports of an association with IgA nephropathy, except in cases having, in addition to LA, the clinical signs of PAPS.6 It is also possible that this patient initially had or may have subsequently developed a Schönlein-Henoch glomerulonephritis or a lupus nephropathy.



These are both conditions with mesangial IgA deposits that pathologists are sometimes unable to differentiate from pure mesangial glomerulonephritis. In the reported cases, the finding of LA alone, without other signs of PAPS, in only one of the sisters (with the same nephropathy and the same clinical sign of hematuria following upper respiratory tract infections) raises the question whether this association was incidental or its occurrence was related to a common immune pathogenetic mechanism.