ClinVar

Description

The c.540+265 G>A variant in the OTC gene has been reported previously in association with neonatal onset ornithine transcarbamylase (OTC) deficiency in hemizygous males (Ogino et al. 2007; Engel et al. 2008). mRNA analysis of c.540+265 G>A found that this variant results in an insertion of 135 bases in intron 5, creates a new splice acceptor site and leads to the creation of a new in-frame Stop codon, which causes loss of normal protein function through nonsense-mediated mRNA decay (Ogino et al. 2007; Engel et al. 2008). The c.540+265 G>A variant was not observed in approximately 6500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project. In summary, we interpret c.540+265 G>A to be a pathogenic variant, and its presence is consistent with the diagnosis of OTC deficiency in this individual. Approximately 20% of females who are heterozygous for variants in the OTC gene are clinically symptomatic with disease severity similar to males with partial deficiency (Yamaguchi et al., 2006; Tuchman et al., 2002).