Clinical Reasoning: A 19-Year-Old Woman With Progressive Weakness and Numbness in Her Arms and Legs.

Acute worsening of chronic weakness and numbness can have diagnostic challenges when trying to distinguish between acquired and hereditary conditions. We present the case of a 19-year-old patient who had acute worsening of chronic symmetric sensory and motor neuropathy with no response to intravenous immunoglobulin. Her story highlights the diagnostic approach for patients with atypical features of acquired vs genetic neuropathies and the importance of interpreting a "pathogenic" gene variant in this clinical context. Readers will explore the diagnostic steps our group has considered to reach our final diagnosis and the management of patients with complex neuropathy.