FIELD : medicine.SUBSTANCE : invention relates to the field of medicine, in particular to nephrology, and is intended to predict the presence of the X-linked type of inheritance of a frequent mutation of the COL4A5 gene in a patient with clinical signs of Alport syndrome. In particular, if the age of manifestation of hematuria is not less than 49 months, but there is no proteinuria, or the age of manifestation of proteinuria is at least 18 years, the presence of the COL4A5 c.1871G>A, p.Gly624Asp mutation is predicted. If the age of manifestation of hematuria is less than or equal to 48 months, if the patient has proteinuria, the age of manifestation of proteinuria is up to 18 years, the patient is not expected to have mutations COL4A5 c.1871G>A, p.Gly624Asp.EFFECT : invention provides an effective diagnosis of Alport syndrome by the presence of a mutation of the COL4A5 gene.1 cl