Abstract
Alport syndrome (AS) is a hereditary kidney disorder of type IV collagen caused by pathogenic variants in the <i>COL4A3</i>, <i>COL4A4</i>, and <i>COL4A5</i> genes. Previously several cases of digenic AS, caused by two pathogenic variants in two of the three <i>COL4A</i> genes, have been reported. Patients with digenic AS may present with a more severe phenotype compared to patients with single variants, depending on the percentage affected type IV trimeric collagen chain. We report a newly discovered case of trigenic AS. A 52-year-old female presented with hematuria at the age of 24 years and developed hypertension by the age of 30. Over the years, she developed chronic kidney disease; the most recent eGFR was 44 mL/min/1.73 m<sup>2</sup>. She has symmetric high-tone sensorineural hearing loss. Full genetic analysis revealed a heterozygous pathogenic variant c.2691del in <i>COL4A3,</i> a heterozygous pathogenic variant c.1663dup in <i>COL4A4,</i> and a complete heterozygous deletion of <i>COL4A5</i>. We describe the first patient with AS caused by pathogenic variants in all three <i>COL4A</i> genes, designated trigenic AS. This case report emphasizes the importance of examining all three <i>COL4A</i> genes, even in patients with a mild Alport phenotype, for optimal follow-up of the patient and adequate genetic counseling of family members.