[Clinical and genetic features of persistent asymptomatic microscopic hematuria in children]

Objective: To explore clinical and genetic features of persistent asymptomatic microscopic hematuria in children. Methods: A retrospective case analysis of 135 individuals admitted to Xi 'an Children's Hospital with persistent asymptomatic microscopic haematuria between January 2016 to December 2023 was conducted. The demographic characteristics, kidney pathology and gene results of 135 individuals were analyzed. One hundred and thirty-five individuals were divided into 2 groups (positive group and negative group) according to family history of glomerulogenic hematuria in first-degree relatives. The differences of hematuria remission, proteinuria and gene variation were compared between the 2 groups. Two independent sample t test, Wilcoxon rank sum test, Pearson Chi-square, Yates' corrected Chi-squared test or Fisher exact test were used for comparison between groups. Results: All 135 children, with 48 males and 87 females, were 8.5 (6.5, 9.5) years old at first presentation. Kidney biopsy was performed in 73 cases (54.1%). Kidney pathology showed mild lesions in 41 cases (56.2%), thin basement membrane disease (TBMD) in 24 cases (32.9%), typical pathological features of Alport syndrome in 5 cases (6.8%), and other manifestations in 3 cases (4.1%). The positive group comprised 52 individuals, whereas the negative group consisted of 83 individuals. The positive group demonstrated a higher susceptibility in proteinuria and gene variation, while the negative group exhibited a greater rate of hematuria remission (χ²=5.00, 5.27, 8.52, all P<0.05). Whole exome sequencing was performed in 80 individuals and 18 individuals (22.5%) had a pathogenic or likely pathogenic variant in COL4A3-5. COL4A5 was the most common gene afected, accounting for 11 cases. The 135 individuals were followed up for 4.2 (2.9, 5.1) years, of which 31 cases (22.9%) had complete hematuria remission at 2.1 (1.4, 2.7) years. Up to March 2024, there were also 7 individuals (5.2%) with varying degrees of proteinuria, and 3 individuals (2.2%) with proteinuria progressed to chronic kidney insufficiency. Conclusions: The most common kidney pathological types in children with persistent asymptomatic microscopic hematuria are minor lesions and TBMD. Children with microscopic hematuria whose first-degree relatives have a family history of hematuria are more likely to have proteinuria and gene variants. COL4A3-5 genetic screening could be considered a priority in these children.