A 7-year-old boy has been an inpatient for 1.5 months. He had been brought to the hospital with complaints of edemas all over his body, low urine output, and headache. Clinical urinalysis: proteins – 7.1 g/L, leukocytes - 1-2 in the vision field, erythrocytes 3-4 in the vision field. During the course of treatment the edemas gradually dissipated, headache abated, diuresis normalized. Daily urine proteins – 3 g/L. Biochemical blood test: total protein – 43.2 g/L, urea – 5.2 mmol/L, cholesterol – 9.2 mmol/L. What glomerulonephritis syndrome is the most likely to be present in the patient?