Approximately 80% of Col2a1-Cre; Csgalnact1flox/—; Csgalnact2flox/— double cKO mice, which were deficient in both Csgalnact1 and Csgalnact2 in chondrocytes, immediately died after birth because of respiratory failure, and the remaining ∼20% of the double KO mice could start spontaneous respiration (Shimbo et al., 2017). The gene discussed is CSGALNACT2; the disease is respiratory failure.