However, there are several reasons that support genetic testing for patients with a confirmed diagnosis of BS, such as the high prevalence of affected parents among BrS patients, the rarity of cases caused by spontaneous mutations (approximately 1%), the significant likelihood of disease manifestation (around 30% of individuals with an SCN5A mutation exhibit ECG changes characteristic of BS, which increases to approximately 80% with the use of sodium channel blockers), and the limited effectiveness of ECG changes in diagnosing at-risk relatives [130]. The gene discussed is SCN5A; the disease is Bloom syndrome.