Clinical and pathological features of children with Alport syndrome in southwest of China

Abstract:

Objective：To analyze the clinical and pathological features of children with Alport syndrome（AS） in southwest of China. Methods：Totally 20 patients with AS in southwest China were retrospectively reviewed and the clinical data were collected. The distri－bution of type Ⅳ collagen α chain in renal and skin tissues was detected by indirect immunofluorescence assay. Clinical and patho－logical features of children with AS were compared among different clinical phenotypes as well. Results：Most children showed micro－scopic hematuria associated with proteinuria as initial symptom. The 24 h urinary protein level was higher in patients with isolated proteinuria than in those with hematuria and proteinuria（H=11.959，P=0.003）. The proportion of uremic patients in the family of chil－dren with proteinuria was（6/16） higher than that in the family of children with hematuria（1/4）. The findings by light microscope mostly revealed mild to moderate mesangial proliferative glomerulonephritis（70.00%）. There was no significant difference in patholog－ical type distribution among AS children with variable clinical phenotypes（χ2=4.149，P=0.900）. About 60% patients with AS had foam cells in kidney interstitium，whose urine protein level was significantly higher than those without foam cells（T=-2.083，P=0.039）. Based on different AS genotypes’ immunofluorescence characteristics of type Ⅳ collagen α5 chains in base membrane，15 patients（75%） were diagnosed as X-linked dominant inherited AS（XLAS） and 5 patients did not determine the inherited types yet according to the deletion of type Ⅳ collagen α5 chains. Two children with AS also detected collagen type Ⅳ α5 chains in epithelial basement membrane and the results were the same as detecting type Ⅳ collagen α5 chains in glomerular basement membrane. Conclusion：In southwest China，hematuria associated with proteinuria is the main initial clinical manifestation in children with AS. The main inheriting type is XLAS（75%）. There was no significant difference in AS children with variable clinical phenotypes，however，the higher the level of proteinuria，the more severe the change in renal tubular interstitial. The diagnosis of XLAS by skin biopsy is consistent with that by renal biopsy and skin biopsy can replace renal biopsy under certain circumstances. Moreover，skin biopsy plays an important role in screening the carriers and making genetic counseling.