GH1 and Costello syndrome: Some children with neonatal hypoglycaemia should be specially monitored for episodes of severe recurrent hypoglycaemia that can relapse several times from birth to childhood in specific syndromes driven by hyperinsulinism (e.g., congenital hyperinsulinism, Beckwith–Wiedmann syndrome, Soto syndrome), insufficient energy supply (i.e., inborn errors of metabolism that result in deficiencies in glycogen, amino acids, or free fatty acids), or deficiency in cortisol or growth hormone (e.g., Costello syndrome, hypopituitarism, congenital adrenal hyperplasia) [23,40,70].