Quiz Form

Question Date: 08/07/2023

Question: 38-years-old lady presented with insidious onset gradually progressive weakness in bilateral lower limbs since 10 years. She was a poor runner in school. She had wasting in intrinsic foot, hammer toes and pes cavus, which disappeared on standing. Neurological examination showed impaired joint position and vibration sense in both her feet till ankle. Similar foot deformities found in her 3 sisters and in her father. Nerve conduction study showed absent SNAPs and low amplitude CMAPs with conduction velocity 28 m/sec with uniform slowing. Which gene is most likely abnormal?

Options:

• GARS
• GJB1
• TRPV4
• PMP22

Correct Answer: PMP22

Explaination: The demyelinating form of CMT, CMT1 has low conduction velocity and uniform slowing. PMP22 duplication is the most common defect found in CMT1A.

Reference: Klein, C. J. Charcot-Marie-Tooth Disease and Other Hereditary Neuropathies. CONTINUUM: Lifelong Learning in Neurology 26, 1224 (2020).