A rare genetic disease characterized by the association of Fanconi syndrome and nephrocalcinosis in addition to neonatal hyperinsulinism and macrosomia. Patients display a phenotype of proximal tubulopathy characterized by generalized aminoaciduria, low molecular weight proteinuria, glycosuria, hyperphosphaturia and hypouricemia. There are also additional features not normally seen in Fanconi syndrome (apart from nephrocalcinosis), namely renal impairment, hypercalciuria with relative hypocalcemia and hypermagnesemia. [from SNOMEDCT_US]