“…Carbamoyl phosphate synthetase I (CPS1) deficiency (CPS1D) is a rare autosomal recessive urea cycle disorder, characterized by hyperammonemia with the incidence of 1/50,000 to 1/300,000 (Díez-Fernández et al, 2015). CPS1D is currently divided into two types of neonatal onset and late onset, whereas CPS1D with severe manifestations of hyperammonemia is common in neonatal-onset patients (Choi et al, 2017; Rokicki et al, 2017; Yang et al, 2017; Zhang et al, 2018). Typically, the neonatal-onset patient with CPS1D appears to be healthy at birth, but deteriorates rapidly into severe hyperammonemia, presenting poor feeding, vomiting, hypotonia, irritability, seizures, hypothermia, lethargy, coma, apnea, and even death after first feeding (Funghini et al, 2012; Choi et al, 2017; Rokicki et al, 2017; Zhang et al, 2018).…”