Clinical characteristics of patients with positive genetic testing for peripheral neuropathies at a tertiary Brazilian neuromuscular outpatient clinic in an university hospital

Objective: To determine prevalent clinical and epidemiological characteristics among patients with positive genetic testing for peripheral neuropathies. Background: Diagnosing peripheral neuropathies frequently necessitates genetic testing. Yet, there is no established protocol to guide neurologists in discerning the appropriate circumstances for requesting genetic testing in a brazilian population. Methods: Seventy-one patients were tested at an outpatient clinic for neuromuscular diseases in Brazil. Only patients with positive genetic tests were included. The prevalence of mutations was registered. Clinical characteristics were retrieved from electronic records (i.e., symptoms, physical exam, and nerve conduction study). Descriptive analyses were conducted. Results: Thirty patients had a positive genetic test. All patients had a Charcot-Marie-Tooth (CMT) disease phenotype. The mean age of diagnosis was 46 years old. Most patients had a mutation in the PMP22 (9/30, 30%), ALMS1 (4/30, 13%), and SH3TC2 (3/30, 10%) genes. Of the nine patients with PMP22 mutation, six (66%) presented numbness, six (66%) had imbalance, and five (55%) presented weakness. Pes cavus and distal atrophy were each reported by two patients (2/9, 22%). Conclusion: Our study highlights key clinical characteristics among patients with positive genetic testing for hereditary neuropathies. We found CMT phenotype was the most prevalent among study participants, with numbness, imbalance, and weakness being recurrent clinical manifestations. Notably, most patients only disclosed diagnosis later in adulthood. This result emphasizes the need to rapidly identify prevalent mutations, symptoms, and associated conditions to order genetic testing for hereditary neuropathies.