Analysis of Sequence Variations in the LDL Receptor Gene in Spain: General Gene Screening Or Search for Specific Alterations?(Molecular Diagnostics and Genetics)
Clinical Chemistry 2006, June, 52, 6
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Autosomal-dominant hypercholesterolemias (ADHs 3 MlM603776) are frequently occurring lipid disorders characterized by increased plasma total cholesterol (TC) and LDL-cholesterol (LDL-C) concentrations and premature coronary atherosclerosis. The frequency is -1 heterozygote in 500 persons worldwide, and 1 homozygote in 1 million persons. Cholesterol concentrations of heterozygous patients are twice as high as those in healthy people, and patients present with tendon xanthomas and atherosclerosis in their second or third decade of life. Homozygotes can present in early childhood with a 6-fold increase in LDL-C concentrations, extensive tendon and cutaneous xanthomas, and coronary atherosclerosis, and they frequently die from myocardial infarction before age 20 (1, 2). ADHs have been classified according to the responsible genetic defect. Familial hypercholesterolemia (FH; MIM 143890) is caused by sequence variations in the gene coding for the receptor that clears LDL-C from plasma (LDLR4 gene). More than 900 sequence variations in this gene have been described (3-5) (databases accessible at http//www.umd.necker.fr and http//www.ucl.ak.uk/fh) and are distributed along the entire length of the gene. When the defect is found in the gene that codes for the LDL receptor ligand, APOB, the ADH is known as familial defective apolipoprotein B100 (FDB). Only 3 sequence variants have been described, and they restrict the binding of apolipoprotein B to the LDL receptor (6-8). A third gene causing ADH is the one coding for the proprotein convertase subtilisin kexin 9 (PCSK9), the role of which is not yet well understood. To date, 4 different PCSK9 sequence variations have been described and have led to the identification of a new form of ADH (9). The clinical features of the different ADHs are very similar, although patients with FDB tend to show a milder phenotype than do FH patients (10, 11). Furthermore, it is known that in FH the type of genetic variation correlates with the severity of the phenotype and response to treatment (12-15); therefore, identification of genetic variations causing ADHs has acquired great clinical importance.
- 2,99 €
- Category: Chemistry
- Published: 01 June 2006
- Publisher: American Association for Clinical Chemistry, Inc.
- Print Length: 13 Pages
- Language: English