A more recent (2021) consensus by experts convened by the ISPG considers that current evidence does support the use of PGx testing for cytochrome P450 genes CYP2D6 and CYP2C19 to inform selection and dosing of commonly used antidepressant and antipsychotic medication, as well as testing for HLA-A and HLA-B when using carbamazepine, HLA-B for oxcarbazepine, PYP2C9, and HLA-B for phenytoin, and when a mitochondrial disorder or a urea cycle disorder is suspected, POLG, OTC, and CSP1 for valproate use (Bousman et al., 2021). Here, HLA-B is linked to urea cycle disorder.