COL4A4 and Alport syndrome: In our study, 1 patient who was clinically diagnosed as having renal disease in pregnancy had pathogenic variants in COL4A3 and COL4A4. Pathogenic mutations in COL4A3, COL4A4, and COL4A5 interfere with the synthesis and/or formation of collagen IV alpha-3-4-5 protomers and networks, resulting in a primary basement membrane disease called Alport syndrome.30