Genetically confirmed familial hypercholesterolemia in outpatients with hypercholesterolemia

Background Familial hypercholesterolemia （FH） is an autosomal dominant disorder of lipoprotein metabolism which can lead to premature coronary heart disease （pCHD）. There are about 3.8 million potential FH patients in China, whereas the clinical and genetic data of FH are limited. Methods Dutch Lipid Clinic Network （DLCN） criteria was used to diagnose FH in outpatients with hypercholesterolemia. Resequencing chip analysis combined with Sanger sequencing validation were used to identify mutations in the definite FH patients according to DLCN criteria. In silico analysis was conducted in mutations with previously unknown pathogenicity. Then, the novel mutant receptors were transfected into human embryo kidney 293 （HEK-293） cells. The binding and the internalization activities of the mu- tant receptors were analyzed by flow cytometry. Results The prevalence of definite FH in outpatients with hypercholesterolemia in this study is 3.2%. Using genetic testing, one homozygous FH （HoFH）, one heterozygous FH （HeFH） and three compound heterozygous FH patients were confirmed. Eight mutations in low-density lipoprotein receptor （LDLR） gene were identified, in which c.357delG was a novel mutation and co-segregated with the FH phenotype. Bioinformatic analysis confirmed that c.357delG was a pathogenic mutation. Furthermore, when compared with the wild-type LDLRs by flow eytometry analysis, the binding and internalization activities of c.357delG mutant LDLRs were reduced by 35% and 49%, respectively. Conclusions This study identified eight LDLR gene mutations in five patients with definite FH, in which c.357delG is a novel pathogenic mutation. These findings increase our understanding of the genetic spectrum of FH in China.

Familial Hypercholesterolemia with Two Mutations in LDLR Gene: A Case Report and Literature Review

We report a case of Familial hypercholesterolemia (FH) with two mutations in low density lipoprotein receptor (LDLR) gene and speculate the correlation between the newly discovered mutation type of LDLR gene and FH. We collected and analyzed the clinical data of the proband in the case and her immediate family members, and detected the LDLR, Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK-9) and Apolipoprotein B (Apo B) gene in the peripheral blood of all the participants. We found that the curative effect of the patient is limited, but no obvious complication was detected. Genetic testing results pointed out that there were two mutations in the patient’s LDLR gene. One was p.W483* mutation in exon 10 (c. 1448 G > A), another was p.T534I mutation in exon 11 (c. 1601 C > T). The p. W483* mutation in exon 10 was detected in the father and sister, additionally p. T534I mutation in exon 11 was detected in the mother. Both the two LDLR gene mutations are inherited from her parents. We hypothesize that the patient in this case was a complex heterozygote. The newly discovered mutation gene (T534I) may be one of the important causes of dyslipidemia in patients, and its adverse effects are more serious than W483* which have been reported. Also, we predict that the T534I mutation will not cause serious early onset of cardiovascular complications.

Proprotein convertase subtilisin/kexin type 9 inhibitor non responses in an adult with a history of coronary revascularization:A case report

BACKGROUND Familial hypercholesterolemia(FH)is an autosomal dominant disorder that is characterized by severely increased low-density lipoprotein(LDL)cholesterol levels.At the same time,elevated LDL levels accelerated the development of coronary heart disease.Several classes of drugs are currently in use to treat FH.Proprotein convertase subtilisin/kexin type 9 inhibitor(PCSK9i)is novel one of these.CASE SUMMARY This manuscript reports a case of FH that responded modestly after treatment with PCSK9i and statin drugs.Of even more concern is that the patient frequently admitted to the hospital during a 12-year follow-up period.Subsequently,we identified a heterozygous mutation,1448G>A(W483X)of the LDL receptor(LDLR)in this patient.The serum levels of PCSK9(proprotein convertase subtilisin/kexin type 9)in the patient was 71.30±26.66 ng/mL,which is close the average level reported in the literature.This LDLR mutation affects LDLR metabolism or structure,which may make it unsuitable for use of PCSK9i.CONCLUSION Our outcome demonstrates that LDLR-W483X represents a partial loss-of-function LDLR and may contribute to PCSK9i ineffective. In the meanwhile, additional measures aretherefore required (particularly with gene sequencing or change the treatment plan) must beinitiated as early as possible. Genetic testing for clinically challenging cases who do not respond toPCSK9i therapy is very helpful.