In this report, we described three cases of COXPD23 caused by mutations in GTPBP3 from Chinese population, one of them (patient 1) with severe neonatal presentation and a fatal outcome, carrying the novel mutations c.413C > T (p. A138V) and c.509_510del (p. E170Gfs∗42) in compound heterozygotes, and the remaining two (patients 2 and 3) with a mild presentation characterized by developmental delay with no significant improvement of the clinical condition during follow-up. Here, GTPBP3 is linked to Global developmental delay.