Chronic Cough and CANVAS (Cerebellar Ataxia With Neuropathy and Bilateral Vestibular Areflexia Syndrome): Screening for Mutations in Subunit 1 of the Replication Factor Complex: Initial Pilot Study

Chronic cough is a frequent cause of Pneumology consultations. CANVAS syndrome (Cerebellar Ataxia with Neuropathy and bilateral Vestibular Areflexia Syndrome) is a progressive and disabling neurological disease that very frequently occurs with chronic cough. This cough invariably appears as a prodromal symptom that precedes neurological symptoms. The biallelic expansion of AAGGG in RFC1, a causal mutation in CANVAS syndrome, appears with high frequency in the general population. Objectives: Main: To determine the presence of biallelic expansion of AAGGG in RFC1 in patients with chronic cough, regardless of the presence of neurological symptoms. Secondary: Describe the phenotypic, functional and inflammatory characteristics of these patients. and Know the relationship between gastroesophageal reflux and chronic cough in patients with CANVAS. Method: A descriptive cross-sectional pilot study including 50 non-smoking patients between the ages of 30 and 99 years with chronic and / or refractory cough as the only manifestation or associated with gastroesophageal reflux. All patients will undergo the pertinent studies for the diagnosis of chronic cough, those who meet criteria for suspicion of gastroesophageal reflux will be requested an esophageal phmetry and esophageal manometry. Peripheral venous blood sample will be obtained for subsequent genetic analysis. Vibration sensitivity will be studied in all patients regardless of the presence of mutation. Those with alterations in vibratory sensitivity or mutations in RFC1 will be referred to the Neurology Service for a complementary neurological evaluation. For the molecular study of the DNA sample of the patients, two techniques will be used: standard Polymerase chain reaction amplification with primers flanking the intron 2 fragment of the RFC1 gene and amplification using Repeated Primed Polymerase chain reaction in 3 independent reactions.