engleski

Thin glomerular basement membrane associated with iga glomerulonephritis

INTRODUCTION AND AIMS: Thin glomerular basement membrane (TGBM) can be diagnosed as an individual disease but it can also be accidental histopathological finding in many primary and secondary glomerulonephritis. Research suggest TGBM is the consequence of collagen type 4 chains mutations. We aimed to explore the prevalence of thin glomerular membranes (TGBM) in patients with IgA glomerulonephritis (IgA GN). METHODS: 175 patients with IgA nephropathy from our hospital's registry diagnosed between 2007. and 2015. were included in the study. Ultrasound guided kidney biopsy was performed on all patients and samples were analysed using light, immunofluorescent and electron microscopy. We measured glomerular basement membrane thickness and the values were standardised for our nephropathology laboratory: 340±36 nm in males and 301±44 nm in females. Clinical geneticist analysed family history of patients with TGBM for the presence of possible hereditary kidney diseases and/or microhematuria. Genome sequencing is being done in order to detect COL4α mutations in patients with positive family history. We present one patient with completed analysis. RESULTS: 34 (19.4%) of 175 patients had TGBM described on electron microscopy analysis. Out of those 13 (38.2%) were female with median age 40 (IQR=17-62). In group of patients with TGBM median serum creatinine levels were 138umol/l (IQR=64-457umol/l) and daily proteinuria 2.2 grams (IQR=0.05-10g). Family history of kidney disease and/or microhematuria was positive in 8 (23.5%) patients. We present one of those patients, aged 59 at the time of diagnosis who presented with asymptomatic proteinuria and erythrocyturia. Maximal daily proteinuria was 1.5 grams, serum creatinine was 138 umol/l with eGFR 48ml/min/1.73m2. Kidney biopsy revealed IgA GN on immunofluorescent microscopy with mesangial immune deposits on electron microiscopy and thin basement membranes. Patients mother and two brothers had erythrocyturia and one brother had chronic kidney disease. Genome analysis showed patient was hemizygous for COL4α missense mutation c.1871G>A, p.Gly624Asp. CONCLUSIONS: According to research data in up to 20% of IgA GN patients patohistological analysis can reveal presence of concomitant TGBM. It is also important to notice that in IgA GN basement membrane can even have changes described as , Alport like changes“. It is debatable weather TGBM is just patohistological variant in IgA GN or manifestation of separate disease which predisposes to IgA GN. The significance of TGBM as an independant factor in loss of kidney function in IgA GN should be further researched. We suggest importance of detailed family history for erythrocyturia and in selected cases collagen type 4 mutations testing.

iga ; glomerulonephritis ; glomerular basement membrane

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