Also, in a study by Teresa Bada-Bosch et al. [12], the finding of 31 autosomal dominant AS patients with COL4A3 or COL4A4 variants highlights the common occurrence of multicystic kidney disease (MKD) (52%) and its association with a poorer renal prognosis, as evidenced by a faster eGFR decline, underscoring the clinical relevance of screening for MKD in this population. Here, COL4A3 is linked to mevalonic aciduria.