A new MFN2 gene mutation resulting in hereditary motor and sensory neuropathy type 6, a family report / 中华神经科杂志

ABSTRACT

ObjectiveTo report clinical, pathological and molecular genetic features in a Chinese family with hereditary motor and sensory neuropathy type 6. MethodsThe index case is a 15 years old boy.He developed progressive distal limb weakness at the age of 5.The disease deteriorated slowly,accompanied with contracture of achilles' tendon. At the age of 11 years old he suffered from decrease of visual acuity. At the age of 12, he found the muscular atrophy of both hands without sensory disturbances.Visual evoked potential revealed prolonged latency of bilateral P100. Ophthalmological examination showed bilateral optic atrophy. His mother had the similar symptoms at the age of 7 and reduced visual acuity at the age of 10. Nerve conduction velocity revealed in both pat1ents no compound motor and sensory nerve action potentials in most nerves or slightly reduced nerve conduction velocities with severely reduced amplitudes of the compound motor and sensory nerve action potentials. Sural nerve biopsy was performed on the proband.The sequence of MFN2 gene was analyzed in DNA from the index, his mother and 100 healthy controls.ResultsSural nerve biopsy revealed severe loss of myelinated fibers with few regenerating clusters.Ultrapathological examination showed a few of atypical bulbs of myelinated fibers, occasionally regenerating clusters, mitochondrial swelling and aggregation in a few of axons. A new mutation of W740R mutation in MFN2 gene has been identified in the index case, her mother, but not in 50 healthy controls. Conclusions A novel MFN2 gene mutation result in hereditary motor and sensory neuropathy type 6.Mild visual loss appeares after the lesion of spinal nerves. Demyelination of peripheral nerve appears in the disease.