In fact, arthrogryposis has been reported in many diseases discussed in this review article: SMARD1 due to mutations in IGHMBP2, XL-SMA due to mutations in UBA1, SP-SMA due to mutations in TVPV4, SMA-LED1 due to mutations in DYNC1H1, and SMA-LED2 due to mutations in BICD2. Here, UBA1 is linked to proximal spinal muscular atrophy.