Optic Neuropathy in Charcot-Marie-Tooth Disease

Area of Science:

• Ophthalmology
• Neurology
• Genetics

Background:

• Charcot-Marie-Tooth disease Type 2A (CMT2A) can affect the optic nerve, but its prevalence and severity compared to other subtypes are unknown.
• Optic nerve involvement is observed in a subset of CMT2A patients.

Purpose of the Study:

• To investigate the prevalence and severity of optic nerve involvement in CMT2A.
• To compare visual acuity and retinal nerve fiber layer (RNFL) thickness in CMT2A patients with other CMT subtypes.

Main Methods:

• High- and low-contrast acuity testing using Sloan letter charts.
• Spectral domain optical coherence tomography (OCT) to measure RNFL and macular thickness.
• Age- and gender-adjusted linear regression analysis for group comparisons.

Main Results:

• One of five CMT2A patients exhibited optic nerve atrophy with reduced acuity (20/160) and RNFL thickness (47.5 μm).
• Other CMT2A patients showed normal acuity and retinal thickness.
• No significant differences in visual acuity or retinal thickness were found between CMT2A, CMT1A, and CMTX1 groups.

Conclusions:

• Optic atrophy is present in some CMT2A patients, but not all, indicating potential mutation-specific effects.
• Low-contrast acuity and OCT may have limited value as universal biomarkers for CMT2A disease severity.
• Optic neuropathy appears specific to certain MFN2 mutations in CMT2A.