CYP1B1 and autosomal recessive disease: PCG has been traditionally viewed as an autosomal recessive disease caused by homozygous or compound heterozygous mutations in a major gene, CYP1B1, which account for 30-50% of cases worldwide (Wiggs and Pasquale, 2017; Aung and Khor, 2016; Lewis et al., 2017).