title: Functional characterization of two low-density lipoprotein receptor gene mutations in two Chinese patients with familial hypercholesterolemia.
abstract: BACKGROUND
  Familial hypercholesterolemia (FH) is an autosomal dominant disease that primarily results from mutations in the low-density lipoprotein receptor (LDLR) gene. We investigated two unrelated Chinese FH patients using gene screening and functional analysis to reveal the pathogenicity and the mechanism by which these mutations cause FH.
  
  
  METHODS
  First, the LDLR gene was sequenced in these patients. Then, mutant receptors were transfected into human embryo kidney 293 (HEK-293) cells, and a confocal laser-scanning microscope was used to observe the localization of mutant proteins. Further, the expression and the internalization activity were analyzed by flow cytometry. Finally, LDLR protein expression and stability was detected by western blot.
  
  
  RESULTS
  Two different LDLR class 2B mutations were detected in two patients. The C201F mutation is a known mutation. However, the G615V mutation is novel. Flow cytometry showed that the expression and internalization activity of the mutant LDLRs were reduced to 73.6% and 82.6% for G615V and 33.2% and 33.5% for C201F, respectively.
  
  
  CONCLUSIONS
  This study identified two LDLR mutations in Chinese patients with FH and analyzed the relationship between the genotype and phenotype of these patients. We found that these mutant LDLRs were defective in transport, which led to a reduction in cholesterol clearance. These results increase our understanding of the mutational spectrum of FH in the Chinese population.
authors.affiliation: Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital Affiliated with Capital Medical University, Beijing, China.
authors.forename: Haihong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital Affiliated with Capital Medical University, Beijing, China.
authors.forename: Shengyuan
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital Affiliated with Capital Medical University, Beijing, China.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital Affiliated with Capital Medical University, Beijing, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Pan
authors.affiliation: Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital Affiliated with Capital Medical University, Beijing, China.
authors.forename: Shiwei
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital Affiliated with Capital Medical University, Beijing, China.
authors.forename: Luya
authors.initials: L
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D015153:Blotting, Western; D004252:DNA Mutational Analysis; D004705:Endocytosis; D005260:Female; D005434:Flow Cytometry; D057809:HEK293 Cells; D006801:Humans; D006938:Hyperlipoproteinemia Type II / Q000235:genetics*; D008077:Lipoproteins, LDL / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D055550:Protein Stability; D011973:Receptors, LDL / Q000235:genetics*
chemical_list: D008077:Lipoproteins, LDL; D050505:Mutant Proteins; D011973:Receptors, LDL