A novel UBA1 gene mutation in a patient with infantile respiratory distress syndrome.

UBA1 is an E1 ubiquitin-activating enzyme that initiates the ubiquitylation of target proteins and is thus a key component of the ubiquitin signaling pathway. Three disorders are associated with pathogenic variants of the UBA1 gene: vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome, lung cancer in never smokers (LCINS), and X-linked spinal muscular atrophy (XL-SMA, SMAX2). We here report a case of infantile respiratory distress syndrome followed by continuing neuromuscular symptoms. We identified a de novo hemizygous mutation, c.1660 C > T (p.Pro554Ser), in exon 15 of the UBA1 gene in this baby. This missense mutation was located with the AAD (active adenylation domain) of the protein, a known hotspot of SMAX2 mutations. This case lends support to the genotype-phenotype correlation regarding the UBA1 mutation and its related diseases.