Here we like to introduce the concept of a mutation type-dependent pattern of transmission based on which severely damaging COL4a3 and a4 chains mutations in heterozygous state are sufficient to determine an autosomal dominant ATS while hypomorphic mutations need to cosegregate together or in association with variants in other genes of the extracellular matrix or podocyte cytoskeleton in order for a fully penetrant phenotype to develop. Here, COL4A3 is linked to Andersen-Tawil syndrome.