However, mutations in the β subunit of mitochondrial trifunctional protein (MTP) (HADHB) causing CMT have been detected in only six patients to date: compound heterozygous mutations in two CMT siblings with early onset axonal sensorimotor neuropathy (11), two unrelated infantile axonal CMT patients (12), and a homozygous mutation in two siblings with axonal CMT (13). This evidence concerns the gene HADHB and Charcot-Marie-Tooth disease.