In other diseases, such as Brugada syndrome, the role of a clear mono- genic disease-causing mutation is less certain, and the genotype does not provide therapeutic or prognostic information for the proband.S4.2.6-5,S4.2.6-10 S4.2.6-12 In ar- rhythmogenic right ventricular cardiomyopathy, some CLINICAL STATEMENTS AND GUIDELINES desmosomal mutation positive individuals do not de- velop disease, indicating that additional mutations and environmental interactions likely influence the clinical development of disease.S4.2.6-13 S4.2.6-16 Importantly, the absence of an identified disease-causing genetic muta- tion does not exclude the presence of disease, and as such, ongoing monitoring and decision-making are done based on the clinical phenotype. Genotyping is frequent- ly most useful when a pathogenic mutation is identified in the proband, such that screening can be applied to relatives who are in a preclinical phase, allowing institu- tion of lifestyle changes, therapy, or ongoing monitoring for those who are gene mutation positive.S4.2.6-7 Refer to Section 7.9 for disease-specific recommendations. In young patients (<40 years of age) without structural heart disease who have unexplained cardiac arrest, unex- plained near drowning, or recurrent exertional syncope, genetic testing may be important to identify an inherited arrhythmia syndrome as a likely cause.S4.2.6-17 S4.2.6-23 Recommendation-Specific Supportive Text 1. 