Clinical characteristics and gene analysis of a family with autosomal dominant Alport syndrome with the onset of nephrotic syndrome / 中华实用儿科临床杂志

The clinical characteristics, mutation analysis results, and family tree of a patient with autosomal dominant Alport syndrome (ADAS), who had nephrotic syndrome as the first manifestation were examined.The proband was a 11-month-old girl who presented with nephrotic syndromes and gross hematuria.During the treatment course, the patient had steroid resistance and a poor response to Cyclosporine and Cyclophosphamide pulse therapy.Renal biopsy was performed 2 years after disease onset.Under the light microscopy, glomerular segmental mesangio-proliferative lesions were observed.The staining of type Ⅳ collagen showed the loss of the α3 chain in the glomerular basement membrane (GBM) and tubular basement membrane, and α5 chain loss in GBM.Electron microscopy showed uneven thickness of GBM, with obviously delaminated and tearing dense basement membrane (BM) layer, showing a typical lace-like change.The segmental BM was loosened and widened.Her father did not develop microscopic hematuria until 10 years later, while her grandmother had asymptomatic hematuria and proteinuria when the proband was diagnosed.A new mutation in the COL4A4 gene was found in the proband, namely c. 1715delG (p.G572Vfs * 81). Her father and grandmother carried the same mutation, but her mother and sister did not have.The clinical manifestation of ADAS is clinically heterogeneous and its incidence may be higher than what we have expected.

Clinical and genetic diagnosis of a pedigree affected with autosomal recessive Alport syndrome / 中华医学遗传学杂志

Objective@#To explore the genetic basis of a child with chronic kidney disease featuring renal shrinkage and creatinine increase.@*Methods@#Peripheral venous blood samples were taken from the child, his brother and two parents and subjected to whole exome sequencing. Suspected mutations were verified by Sanger sequencing. Bioinformatic analysis was carried out to predict the influence of mutations on the structure and function of the protein product.@*Results@#High-throughput and Sanger sequencing revealed that the child has carried compound heterozygous mutations of the COL4A4 gene, namely c. 4550T>G in exon 47 (inherited from his mother) and c. 199C>T in exon 5 (inherited from his father). Neither mutation was reported previously. Bioinformatic analysis showed that both mutations have located in highly conserved regions. The same mutations were not found in his brother.@*Conclusion@#The compound heterozygous c. 4550T>G and c. 199C>T mutations probably underlie the disease in this child. The findings have enriched the mutation spectrum of the COL4A4 gene.

Research progress of benign familial hematuria / 中华实用儿科临床杂志

Benign familial hematuria,also called thin basement membrane nephropathy,is caused by a heterozygous mutation in the COL4A3 or COL4A4 gene.The prognosis of the patients with benign familial hematuria,who present isolated hematuria without associated with proteinuria and normal renal function,is good in childhood.However,the prognosis of part of the patients with benign familial hematuria,who appear proteinuria,hypertension,chronic renal failure and end-stage kidney disease,is poor in adulthood.Therefore,the patients with benign familial hematuria should be carried on the long-term follow-up,and may be reviewed every 1-2 years for hypertension,proteinuria,and renal impairment.Treatment for benign familial hematuria should include an angiotensin converting enzyme inhibitor to delay the onset of renal failure.

Diagnosis of a boy with sporadic Alport syndrome using next generation sequencing and literature review / 中华实用儿科临床杂志

Objective To study the feasibility of testing three disease-causing genes for Alport syndrome,COL4A3,COL4A4 and COL4AS,in diagnosing patients with sporadic Alport syndrome by using targeted capture and next generation sequencing.Methods The clinical data of a 9-year-old boy suspected with Alport syndrome were collected.Genomic DNA was extracted using standard procedures from the peripheral blood leukocytes of the patient and his parents,respectively.Targeted capture and next generation sequencing and Sanger sequencing were applied to analyze the mutations in the 3 disease-causing genes.Clinical data of cases reported already with autosomal recessive Alport syndrome caused by the mutations in the COL4A4 gene were summarized.Results The patient was presented with neither family history of hematuria nor chronic renal failure.Haematuria and proteinuria were found at the age of 1 year.The patient presented with episodes of macrohaematuria and gradually developed nephrotic-level proteinuria.At the age of 8 years 7 months,bilateral sensorineural hearing loss was diagnosed.So a probable diagnosis of Alport syndrome was postulated.A compound heterozygous pathogenic mutations of 3578-1G ＞ A and 3967 C ＞ T(Q1323X) were identified in the COL4A4 gene in the patient.The mutation of 3578-1G ＞ A was inherited from his father,and the mutation of Q1323X from his mother.The patient was decisively diagnosed with autosomal recessive Alport syndrome.Conclusions The test of COL4A3,COL4A4 and COL4A5 genes can help diagnose patients with sporadic Alport syndrome by using targeted capture and next generation sequencing.