Familial hypercholesterolemia in China half a century: A review of published literature

AIMS

To investigate the status of familial hypercholesterolemia (FH) research and the characteristics of patients with FH in China.

METHODS

Published papers in Chinese or English language from PubMed, SinoMed and CNKI databases from 1971 to March 2018 were searched using 'Familial hypercholesterolemia', 'Chinese' and 'Han' as keywords. A systematic review of studies on familial hypercholesterolemia was then conducted.

RESULTS

A total of 391 articles were found, in which 22% were in English and 78% were in Chinese; approximately 43% are case reports and 34% are genetic reports according to the study type; 52% discussed the status of the disease and 11% investigated the subclinical status according to the study content. Furthermore, 96% of the articles were published by tertiary hospitals and 46% were conducted by cardiologists. The first expert consensus was issued in February 2018. Of the 163 case reports published before 2018, 48.7% used the Chinese FH clinical diagnostic criteria and 34.4% did not clearly indicate the diagnostic criteria. The incidence rates of low-density lipoprotein receptor (LDLR) and apolipoprotein B (APOB) mutations were 82% and 9%, and proprotein convertase subtilisin/kexin type 9 (PCSK9) mutations were rare in Chinese patients with FH. However, the data on lipid-lowering treatment rates, compliance rates and cardiovascular events in FH remain insufficient.

CONCLUSIONS

Large-scale epidemiological investigation of FH has not been demonstrated, the recognition of FH remains rudimentary, and the guidelines are incomplete in China. The diagnosis and management of Chinese FH needs to be improved.

Mutation detection in Chinese patients with familial hypercholesterolemia

Background

Familial hypercholesterolemia (FH) is the first molecularly and clinically characterized genetic disease of lipid metabolism. It is an autosomal dominant disorder with significantly elevated levels of total cholesterol and low density of lipoprotein cholesterol in serum, which would lead to extensive xanthomas and premature coronary heart disease. Mutations in low density lipoprotein receptor (LDLR), proprotein convertase subtilisin/kexin type 9 and Apo lipoprotein B-100 (APOB) have been identified to be the underlying cause of this disease.

Methods

Genetic testing and reports of the mutations in the Chinese population are still limited. In this study, 11 unrelated Chinese FH families were enrolled to detect the candidate gene variants by DNA direct sequencing.

Results and conclusion

We identified 12 mutations (11 in LDLR and one in APOB) in ten FH families. Three novel LDLR mutations (c.516C>A/p.D172E, c.1720C>A/p.R574S and c.760C>T/p.Q254X) were identified and co-segregated with the affected individuals in the families. Our discoveries not only further supports the significant role of LDLR in FH, but also expands the spectrum of LDLR mutations. These new insights will contribute to the genetic diagnosis and counseling of FH patients.

The distribution and characteristics of LDL receptor mutations in China: A systematic review

Familial hypercholesterolemia (FH) is a common and serious dominant genetic disease, and its main pathogenic gene is the low-density lipoprotein receptor (LDLR) gene. This study aimed to perform a systematic review of LDLR mutations in China. Using PubMed, Embase, Wanfang (Chinese), the Chinese National Knowledge Infrastructure (Chinese), and the Chinese Biological and Medical database (Chinese), public data were limited to December 2014. The Medical Subject Headings terms and the following key words were used: “familial hypercholesterolemia”, “Chinese”, “China”, “Hong Kong”, and “Taiwan”. A total of 74 studies including 295 probands with 131 LDLR mutations were identified. Most of the mutations were located in exon 4 of LDLR and approximately 60% of the mutations were missense mutations. Thirty new mutations that were not recorded in the LDLR databases were found. In silico analysis revealed that most of the mutations were pathogenic. The primary LDLR mutations were C308Y, H562Y, and A606T, and all of the mutations had functional significance. Prevalence data suggest that there are nearly 3.8 million FH patients in China, although reported numbers are much smaller, suggesting that FH is widely misunderstood. This systematic review provides information that is specific to China for inclusion in the international FH database.

Identification of the gene defect responsible for severe hypercholesterolaemia using whole-exome sequencing

Familial hypercholesterolaemia (FH) is a serious genetic metabolic disease. We identified a specific family in which the proband had typical homozygous phenotype of FH, but couldn’t detect any mutations in usual pathogenic genes using traditional sequencing. This study is the first attempt to use whole exome sequencing (WES) to identify the pathogenic genes in Chinese FH. The routine examinations were performed on all parentage members, and WES on 5 members. We used bioinformatics methods to splice and filter out the pathogenic gene. Finally, Sanger sequencing and cDNA sequencing were used to verify the candidate genes. Half of parentage members had got hypercholesterolaemia. WES identified LDLR IVS8[−10] as a candidate mutation from 222,267 variations. The Sanger sequencing showed proband had a homozygous mutation inherited from his parents, and this loci were cosegregated with FH phenotype. The cDNA sequencing revealed that this mutations caused abnormal shearing. This mutation was first identified in Chinese patients, and this homozygous mutation is a new genetic type of FH. This is the first time that WES was used in Chinese FH patients. We detected a novel genetic type of LDLR homozygous mutation. WES is powerful tools to identify specific FH families with potentially pathogenic gene mutations.

Novel mutations of low-density lipoprotein receptor gene in China patients with familial hypercholesterolemia

Familial hypercholesterolaemia (FH) is an autosomal dominant genetic disorder, associated with elevated level of serum low-density lipoprotein-cholesterol (LDL-C), which can lead to premature cardiovascular disease (CVD). Mutations in low density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) have been identified to be the underlying cause of this disease. Genetic research of FH has already been extensively studied all over the world. However, reports of FH mutations in the Chinese population are still limited. In this paper, 20 unrelated FH families were enrolled to detect the candidate gene variants in Chinese FH population by DNA direct sequencing. We identified 12 LDLR variants in 13 FH probands. Importantly, we first reported two unique mutations (c.2000_2000 delG/p.C667LfsX6 and c.605T>C/p.F202S) in LDLR gene. Our discoveries expand the spectrum of LDLR mutations and contribute to the genetic diagnosis and counseling for FH patients.