The p.R63W mutation in the hepatocyte nuclear factor-4 alpha (HNF4A) results in macrosomia and atypical Fanconi syndrome, in addition to hyperinsulinaemic hypoglycaemia (HI).
We report six patients heterozygous for the p.R76WHNF4A mutation who have Fanconi syndrome and nephrocalcinosis in addition to neonatal hyperinsulinism and macrosomia.