HADHB mutations cause infantile-onset axonal Charcot-Marie-Tooth disease: A report of two cases

Mitochondrial trifunctional protein deficiency (MTPD) is a rare disorder caused by mutations in the HADHA and I-IADHB genes. Here, we report on two Han Chinese patients with HADHB mutation-associated infantile axonal Charcot-Maric-Tooth disease (IACMT). Both patients were unrelated. Case 1 was a 19-year-old man, and case 2 was a 5-year-old boy. Both had delayed motor development and slowly-progressing distal muscle weakness with areflexia and foot deformities. The electrophysiology findings were compatible with axonal polyncuropathy in both patients. Blood tandem mass spectrometry showed increased concentrations of multiple acykarnitines. Nerve biopsies showed axonal neuropathy with a moderate loss of myelinated fibers. Gene analysis identified two compound heterozygous mutations (c.184A>G/c.340A>G and c.488G>A/c.1175C>T, respectively) in the HADHB gene. The c.488G>A mutation was novel. This study broadens the phenotype of MTPD and suggests that the genetic testing of patients suffering from IACMT should include the HADHB gene.