COL4A4 and Alport syndrome: In addition, as the screening for CNVs using NGS data may not sufficiently detect CNVs of small size (smaller than 1,000 bp), we add MLPA analysis for the patients who are strongly suspected of having Alport syndrome from their clinical findings even if any pathogenic variants in COL4A3/COL4A4/COL4A5 genes were not detected by NGS and RNA sequencing.