Hereditary motor and sensory neuropathy type VIA with optic nerve pallor in two sisters with pathologic myopia: a case series and review

Purpose: Hereditary Motor Sensory Neuropathy Type VIA with Optic Atrophy (HMSN6A) is a rare variant subtype of mitofusin 2 (MFN2) associated Charcot-Marie-Tooth disease, with ophthalmic manifestations largely limited to optic atrophy. We report a case series of two sisters with HMSN6A corresponding to known variants in the MFN2 gene. The proband's mother, maternal aunt, and maternal grandfather were also reportedly affected with the condition, although not examined at our institution. The clinical presentations of the proband and her sister are reviewed in detail. In addition, a comprehensive review of ophthalmic findings from prior reported cases of HMSN6A is provided.

Observations: HMSN6A is a neurologic disorder characterized by a motor sensory axonal neuropathy and optic atrophy. A range of additional ophthalmic manifestations have been reported in the literature. We highlight the proband and her sister who demonstrate this phenotype but also manifested other ocular abnormalities from an early age. In addition to optic nerve pallor, both sisters had additional ophthalmic features of bilateral pathologic myopia, limited vision, nystagmus, and strabismus.

Conclusions and importance: This case series and review describe the ophthalmologic findings of HMSN6A and provides incentive to further investigate the correlation between molecular findings and the phenotype.