Two patients were diagnosed with a GAMT deficiency (both of consanguineous descent and with Arab and Caucasian ethnicity from Syria and Albania, respectively) and four with a CRTR deficiency (three Caucasian ethnicity from Balkan region and Switzerland, and one Ashkenazi from Israel). The gene discussed is SLC6A8; the disease is hyperinsulinemic hypoglycemia, familial, 4.