From both Patients 5 and 6, their PBMC specimens from Visits 2 were MD/PRD-positive and both had relatively high mtDNA copy numbers, 669 and 478 copies/cell, respectively; compared to the Visit 1 (one month post-induction therapy) PBMC specimens which were MD/PRD-negative and had mtDNA values of 127 and 156 copies/cell, respectively. The gene discussed is PEPD; the disease is Menkes disease.