Reverse phenotyping allowed correct identification of 15 patients with Dent disease, six patients with Lowe syndrome, five patients with methylmalonic aciduria (CblC type), five patients with NPHP, two patients with Fabry disease, one patient with Alport syndrome, one patient with C3 nephropathy, one patient with hyperoxaluria, one patient with rhabdomyolysis syndrome, one patient with UMOD-associated FSGS, one patient with TTC21B-associated FSGS and one patient with APE-associated Lipid nephropathy, respectively. The gene discussed is TTC21B; the disease is Methylmalonic aciduria.