Rationale:We report a rare case of hypertrophic cardiomyopathy (HCM) caused by a heterozygous variant in TTR gene.Patient concerns:The proband had been vomiting without obvious inducement since the age of 27, accompanied by the expulsion of stomach contents. At the age of 28, she began to suddenly syncope.Diagnosis:Cardiac magnetic resonance showed thickening of the right ventricular lateral wall and ventricular septum. The left ventricular diastolic function was limited. Targeted Sanger sequencing validates the presence of mutation p.Leu75Pro in TTR gene.Interventions and outcomes:After admission to hospital for syncope, she was given metoprolol tablets 25 mg bid, spironolactone tablets 20 mg qd, and trimetazidine 20 mg tid. Her symptoms improved after taking the medicine.Lessons:The results of this case show that HCM caused by TTR mutation is not easy to be identified and treatment is easy to be delayed. Therefore, high-risk patients with amyloidosis should be evaluated as soon as possible. Timely diagnosis of HCM caused by TTR mutation before irreversible organ damage is essential for proper treatment and better outcomes.