Based on previous studies, the four PEX2 variants chosen by us show a range in clinical severity for classic PBD-ZSD (Shimozawa et al., 1992, 1999; Mandel et al., 1994; Imamura et al., 1998; Fujiwara et al., 2000; Gootjes et al., 2004; Mignarri et al., 2012). The gene discussed is PEX2; the disease is peroxisome biogenesis disorder.