Genetic variations in familial hypercholesterolemia and cascade screening in East Asians

Background Familial hypercholesterolemia (FH) is a monogenic disorder of lipoprotein metabolism leading to an increased risk of premature cardiovascular disease. Genetic testing for FH is not commonly used in Asian countries. We aimed to define the genetic spectrum of FH in Hong Kong and to test the feasibility of cascade genetic screening. Methods Ninety‐six Chinese subjects with a clinical diagnosis of FH were recruited, and family‐based cascade screening incorporating genetic testing results was performed. Results Forty‐two distinct mutations were identified in 67% of the index FH cases. The majority of causative mutations were in the LDLR gene. The three commonest mutations in the LDLR gene were NM_000527.4(LDLR): c.1241 T>G, NM_000527.4(LDLR): c.1474G>A, and NM_000527.4(LDLR): c. 682G>A, and nine novel variants were identified. The NM_000384.2(APOB): c.10579 C>T variant of the APOB gene was found in 5% of the index subjects. The presence of causative mutation significantly increased the odds of successful family recruitment for screening with an OR of 3.7 (95% CI: 1.53–9.11, p = 0.004). Conclusion Approximately two‐third of the subjects in this clinically ascertained sample of patients with FH had a discrete genetic basis. Genetic identification improves the response rate and efficiency of family screening. This study investigated the genetic spectrum in a clinically ascertained cohort of Chinese patients with familial hypercholesterolemia in Hong Kong. The three most common mutations altogether accounted for a combined frequency of 21% among the cohort. We assessed the feasibility of cascade screening to identify untreated patients and showed that having an identifiable genetic cause increases the performance of systematic family tracing.