Neonatal nonketotic hyperglycinemia: a case report and literature review / 中国新生儿科杂志

ABSTRACT

Objective:To study the phenotypes and genotypes of neonatal nonketotic hyperglycinemia (NKH).Methods:A neonate with severe NKH admitted to our hospital was retrospectively analyzed. Using keywords 'glycine cleavage enzyme', 'glycine decarboxylase', 'nonketotic hyperglycinemia' and 'glycine encephalopathy' (both in Chinese and English), multiple medical databases were searched until December 31, 2022. The clinical phenotypes and genotypes of neonatal NKH were summarized.Results:For our case, the neonate was lethargy and had no appetite on the second day of life, followed by recurrent seizures and irregular breathing, requiring mechanical ventilation. She died at 3 weeks of age. Two compound heterozygous variants were found in GLDC gene from whole exome sequencing , one was c.848C>G(p.A283G) of maternal origin and one was c.1607G>A(p.R536Q) of paternal origin. The former was a novel mutation. A total of 54 cases (including this case) were collected. The main clinical manifestations included poor feeding, decreased muscle tone, hiccups, progressive lethargy, irregular breathing, apnea and neonatal seizures. 42 cases (77.8%) had GLDC gene mutations, 9 cases (16.7%) had AMT gene mutations, 2 cases (3.7%) had LIAS gene mutations and 1 case (1.9%) had GCSH gene mutations. Conclusions:Neurological manifestations are most common in neonatal NKH with wide clinical variations. GLDC gene mutations are the predominant pathogenic mutations.