Alport syndrome is a hereditary kidney disease characterized clinically by hematuria, sensorineural deafness, and progressive renal dysfunction. Although it can have various inheritance patterns, it is primarily inherited in an X-linked dominant manner, with the defective gene located at Xq22 on the long arm of the X chromosome. The fundamental defect in this syndrome is an abnormality in the α5 chain of type IV collagen in the basement membrane.

bubble_chart Clinical Manifestations

The disease can occur in both sexes, but symptoms are typically more pronounced in males. Renal function often progressively declines, with most patients developing chronic renal failure by the age of 20–30. The onset is usually marked by hematuria, and although proteinuria is generally absent initially, it gradually increases as the disease progresses. Approximately half of the cases are accompanied by high-frequency sensorineural deafness. About one-third of affected children exhibit ocular abnormalities, with characteristic features including conical lens and macular lesions. As the condition advances, hypertension and declining renal function develop, eventually leading to uremia. Additionally, some cases may present with esophageal, bronchial, or genital leiomyomas, thrombocytopenia, and giant platelet disorders. A positive family history is often reported.

bubble_chart Auxiliary Examination

1. Urinalysis: Presence of hematuria, sometimes accompanied by varying degrees of proteinuria. Urinary sediment may reveal red blood cells, white blood cells, and casts.
2. Blood generation and transformation and renal function tests: May show hyperprolinemia hematuria, with renal function decline in the late stage [third stage], eventually leading to uremic changes.
3. Renal pathology: Light microscopy may show no specific changes initially, but in the late stage [third stage], glomerulosclerosis, tubular atrophy, interstitial fibrosis, and occasionally foam cells may be observed. Electron microscopy reveals characteristic changes: layered and thickened basement membrane with a basket-weave pattern. Immunofluorescence typically shows no deposition of Ig or complement. In recent years, immunofluorescence or immunohistochemistry for type IV collagen α5 chain has been used, showing negative results in patients, discontinuous linear positivity along the basement membrane in female carriers, and continuous linear deposition in healthy individuals. Skin biopsy exhibits similar changes.

bubble_chart Treatment Measures

There is no specific treatment for this condition. Regular attention should be paid to preventing infections and protecting renal function. Blood pressure should be controlled in patients with hypertension. For those reaching end-stage renal failure, symptomatic and dialysis treatments are required. After kidney transplantation, a few cases may develop anti-basement membrane nephritis in the transplanted kidney. Genetic counseling should be provided for this condition, and gene carriers can be identified through the expression of type IV collagen α5 chain in skin biopsies.

bubble_chart Differentiation

It should be differentiated from other common causes of hematuria in children, especially familial benign hematuria, which is characterized by thin glomerular basement membranes on renal biopsy and a benign clinical course.