The precise prevalence of Alport syndrome in the US is uncertain, but estimates of the prevalence of heterozygous pathogenic variants in these genes are ~1 in 100 individuals for either COL4A3 or COL4A4, and ~1 in 2000 individuals for hemizygous or heterozygous variants in COL4A5 (Gibson et al., 2021). Here, COL4A4 is linked to Alport syndrome.