We recently reported a cohort of patients affected by hyperinsulinaemic hypoglycaemia (HI) and autosomal recessive polycystic kidney disease (HIPKD) and identified a specific underlying variant in the promotor of PMM2, which was found either in homozygosity or in trans with deleterious variants in PMM2 (Cabezas et al. 2017). The gene discussed is PMM2; the disease is autosomal recessive polycystic kidney disease.