A new frameshift variation of PAX2 gene in a child with focal segmental glomerulosclerosis and literature review

Objective To understand the clinical and pathological characteristics of hereditary chronic kidney disease in children and explore the pathogenic gene mutation sites and the relationship between gene mutation and clinical phenotype, in order to achieve early diagnosis and early prevention.Methods A child patient with suspected hereditary chronic kidney disease who were admitted to Xuzhou Children's Hospital Affiliated to Xuzhou Medical University were enrolled. Clinical data were collected from the patient and his immediate family members. Renal puncture biopsy was performed. Meanwhile, the second-generation gene sequencing was used to detect gene mutation sites in the patient, his parents and sister, and to identify possible mutation sites. These data were also compared with normal individuals in the family.Results The child patient was a 14-year old boy, who first presented symptoms at 3-year old, with the main clinical manifestations of proteinuria and nocturia, and did not receive normal treatment. Urine proteinuria (PRO) ++-+++, with increasing bedwetting symptoms, which however did not attract much attention from his parents. Two years ago, hepatic and renal functions were examined in local hospitals, and no abnormalities were reported. On August 19, 2019, the patient was admitted to our hospital for bedwetting, and the outpatient test showed urine PRO +++,blood urea nitrogen (BUN) 10.65 mmol/L and creatinine (SCr) 159 μmol/L. Kidney ultrasound indicated shrunken kidneys in both sides. The pathological results of renal biopsy showed focal segmental glomerulosclerosis (FSGS). Gene sequencing indicated a PAX2 gene mutation at the c.143delGp. Gly48Valfs * 35 cleavage site, and there is currently no record in the population. Therefore,it was considered that the patient had a new frameshift mutation in PAX2 gene. Conclusions The patient manifests with chronic kidney disease and diagnosed by renal biopsy with FSGS, with a new frameshift mutation of PAX2 gene through gene sequencing. For child patients with chronic kidney disease of unknown etiology, it is necessary to improve pathological examination in the kidneys and gene sequencing, in order to make a clear diagnosis.