Abstract Objective To investigate the genotypes of the pathogenic gene COL4A5 and the characteristics of clinical phenotypes in children with Alport syndrome (AS). Methods A retrospective analysis was performed for the genetic testing results and clinical data of 19 AS children with COL4A5 gene mutations. Results Among the 19 children with AS caused by COL4A5 gene mutations, 1 (5%) carried a new mutation of the COL4A5 gene, i.e., c.3372A>G(p.P1124=) and presented with AS coexisting with IgA vasculitis nephritis; 3 children (16%) had large fragment deletion of the COL4A5 gene, among whom 2 children (case 7 had a new mutation site of loss51-53) had gross hematuria and albuminuria at the onset, and 1 child (case 13 had a new mutation site of loss3-53) only had microscopic hematuria, while the other 15 children (79%) had common clinical phenotypes of AS, among whom 7 carried new mutations of the COL4A5 gene. Among all 19 children, 3 children (16%) who carried COL4A5 gene mutations also had COL4A4 gene mutations, and 1 child (5%) had COL4A3 gene mutations. Among these children with double gene mutations, 2 had gross hematuria and proteinuria at the onset. Conclusions This study expands the genotype and phenotype spectrums of the pathogenic gene COL4A5 for AS. Children with large fragment deletion of the COL4A5 gene or double gene mutations of COL4A5 with COL4A3 or COL4A4 tend to have more serious clinical manifestations.
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