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.

A descriptive cross-sectional pilot study that included 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 suspected gastroesophageal reflux will be asked for an esophageal phmetry and esophageal manometry, according to the usual clinical practice.

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.

Inclusion Criteria:

• Non-smokers
• Aged between 30 and 99 years
• with chronic and / or refractory cough as the only manifestation or associated with gastroesophageal reflux, who have signed the informed consent will be included.

Exclusion Criteria:

• Other causes of cough other than gastroesophageal reflux: pneumological diseases (asthma, Chronic obstructive pulmonary disease, bronchiectasis, tracheomalacia, cystic fibrosis, residual pleural diseases, interstitial diseases, infectious diseases.)
• Upper airway pathologies (rhinitis, sinusitis)
• Foreign bodies
• Smokers or ex-smokers
• Symptoms of associated respiratory allergies
• Severe associated comorbidity.
• Autoimmune disease or systemic inflammatory disease.
• Active immunodeficiency.
• Neoplastic disease.

A total of 50 patients, non-smokers, aged between 30 and 99 years, with chronic and / or refractory cough as the only manifestation or associated with gastroesophageal reflux, who have signed the informed consent will be included.

Chronic cough will be defined as cough lasting more than 8 weeks that is not related to an acute (3 weeks) or subacute (3-8 weeks) process.

• Study design (from November 2020 to June 2021): In this phase, the protocol will be elaborated, the study materials will be edited, the database design will be carried out, meetings will be held with the researchers to resolve doubts The logistical aspects will be prepared for the start of the study and the project will be presented to the Hospital's ethics committee.
• Recruitment period: one year (study start in June 2021): In this phase, patients will be identified, data will be collected and entered. This phase would end in June 2022.
• Period of analysis of the genetic samples, purification and analysis of the data: this phase is calculated to be carried out in 6 months (June 2022 to December 2022)
• Period of interpretation of the results and writing of memory: for the publication of the results (December 2023 to June 2024).