UBA1 and X-linked distal arthrogryposis multiplex congenita: Up to December 2020, the UBA1 (Ubiquitin-Like Modifier-Activating Enzyme 1), encoding one of the two E1 enzyme isoforms that initiates ubiquitylation in cell’s cytoplasm, had been associated to the X-linked infantile spinal muscular atrophy in patients with germline mutations.