Moreover, deficiency in the co-chaperone DNAJC12 was recognized as a cause of inherited HPA with symptoms like BH4 deficiency [46]. DNAJC12 helps control the folding, degradation, and translocation of hydroxylases so that a DNAJC12 deficiency could lead to inappropriate folding of PAH [46]. This evidence concerns the gene DNAJC12 and pulmonary arterial hypertension.