GNPAT and porphyria cutanea tarda: Compared to the European (non-Finnish) EXAC population, GNPAT D519G was significantly enriched in patients with fPCT (p = 0.0014) but not in patients with sPCT (p = 0.4477) (Table 2) Within the two PCT populations, GNPAT D519G was significantly more frequent in fPCT (29.3%) compared to sPCT (18.0%) (p = 0.004).