Based on the bone scan results, the patients were classified as ATTR positive (patients with high myocardial uptake of the radiotracer), AL positive (patients with low/absent myocardial uptake of the radiotracer, however, the patients were confirmed with AL by using other investigations) and non-ATTR (patients with low/absent myocardial uptake of the radiotracer, however the patients were not confirmed with AL cardiac amyloidosis). This evidence concerns the gene TTR and cardiac amyloidosis.