Genetic Testing Yield and Clinical Characteristics of Hypertrophic Cardiomyopathy in Understudied Ethnic Groups: Insights From a New Zealand National Registry

Background: Aotearoa/New Zealand has a multiethnic population. Patients with hypertrophic cardiomyopathy (HCM) are enrolled in the national Cardiac Inherited Diseases Registry New Zealand. Here, we report the characteristics of Cardiac Inherited Diseases Registry New Zealand HCM probands with and without pathogenic or likely pathogenic (P/LP) genetic variants for HCM, and assess genetic testing yield and variant spectrum by self-identified ethnicity.

Methods: Probands with HCM and enrolled in Cardiac Inherited Diseases Registry New Zealand who have undergone clinical genetic testing over a 17-year period were included. Clinical data, family history, and genetic test results were analyzed.

Results: Of 336 probands, 121 (36%) were women, 220 (66%) were European ethnicity, 41 (12%) were Māori, 26 (8%) were Pacific people, and 49 (15%) were other ethnicities. Thirteen probands (4%) presented with sudden death and 19 (6%) with cardiac arrest. A total of 134 (40%) had a P/LP variant identified; most commonly in the MYBPC3 gene (60%) followed by the MYH7 gene (24%). A P/LP variant was identified in 27% of Māori or Pacific probands versus 43% European or other ethnicity probands (P=0.022); 16% of Māori or Pacific probands had a variant of uncertain significance identified, compared with 9% of European or other ethnicity probands (P=0.092). Women more often had a P/LP variant identified than men (48% versus 35%; P=0.032), and variant-positive probands were younger at clinical diagnosis than variant of uncertain significance/variant-negative probands (39±17 versus 50±17 years; P<0.001) and more likely to have experienced cardiac arrest or sudden death events over their lifetime (P=0.002).

Conclusions: Carriage of a P/LP variant in HCM probands is associated with presentation at younger age, and cardiac arrest or sudden death events. Māori or Pacific probands were less likely to have a P/LP variant identified than European or other ethnicity probands.