,6 Consequently, heterozygous PAX2 variants can cause kidney and eye anomalies as well as hearing loss, an autosomal dominant disorder known as RCS or papillorenal syndrome.5, 6, 7 Mice with a heterozygous PAX2 LOF variant present with developmental defects, including kidney manifestations, similar to human RCS8 with increased apoptosis and reduced branching of the ureteric bud in fetal kidneys.9 The gene discussed is PAX2; the disease is renal coloboma syndrome.