A Korean Case of β-Ureidopropionase Deficiency Presenting with Intractable Seizure, Global Developmental Delay, and Microcephaly.

β-Ureidopropionase deficiency (OMIM #613161) is a rare autosomal recessive inborn error of metabolism due to mutations in the UPB1 gene, which encodes the third enzyme involved in the pyrimidine degradation pathway. A total of 28 cases have been reported, mainly presenting with seizures, microcephaly, and intellectual disabilities. However, 11 of them were asymptomatic cases (Nakajima et al., J Inherit Metab Dis 37(5):801-812, 2014). We report on a 9-year-old female presenting with intractable epilepsy, microcephaly, and global developmental delay. She was homozygous for p.R326Q (c.977G>A) and heterozygous for p.G31S (c.91G>A) in the UPB1 gene, detected by targeted next-generation sequencing test and subsequently confirmed by biochemical analysis of urine, plasma, and cerebrospinal fluid (CSF) using reversed-phase HPLC, combined with electrospray tandem mass spectrometry. We report a first Korean female case with β-ureidopropionase deficiency.