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Clinically applicable mutation screening in familial hypercholesterolemia
H Nissen1, P Guldberg, A B Hansen
1Department of Clinical Chemistry, Odense University Hospital, Denmark.
Insights
A new denaturing gradient gel electrophoresis (DGGE) assay accurately identifies mutations causing familial hypercholesterolemia (FH) and familial defective apo B-100 (FDB). This sensitive method aids in precise diagnosis and improved patient management.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- Familial hypercholesterolemia (FH) and familial defective apo B-100 (FDB) are clinically similar genetic disorders caused by mutations in the LDLR or apo B-100 genes, respectively.
- Traditional diagnostic methods for FH can be inaccurate, hindering precise prognostic evaluation and genetic counseling.
- Existing genetic screening methods are often too complex for routine clinical application.
Purpose of the Study:
- To develop a rapid, sensitive, and clinically applicable mutation screening assay for FH and FDB.
- To improve diagnostic accuracy and facilitate differentiated prognostic and therapeutic evaluations for affected families.
Main Methods:
- A novel mutation screening assay utilizing denaturing gradient gel electrophoresis (DGGE) was designed.
- The assay targets the LDLR promoter, all 18 LDLR exons and splice sites, and the codon 3500 region of apo B-100.
- Identified mutation hotspots are subsequently confirmed by sequencing.
Main Results:
- The DGGE-based assay can pinpoint mutation locations within 24 hours.
- The assay demonstrated high sensitivity, detecting 27 different mutations and polymorphisms across the targeted regions (excluding LDLR exon 16).
Conclusions:
- A simple, sensitive, and clinically applicable DGGE mutation screening assay can identify the underlying genetic cause in most FH/FDB families.
- This assay provides a valuable tool for more accurate prognostic and therapeutic management of patients with FH and FDB.
Abstract:
Mutations in the LDL receptor (LDLR) gene and the codon 3500 region of the apolipoprotein (apo) B-100 gene result in the clinically indistinguishable phenotypes designated familial hypercholesterolemia (FH) and familial defective apo B-100 (FDB), respectively. Introduction of genetic diagnosis in phenotypic FH families may remove the diagnostic inaccuracies known from traditional clinical/biochemical FH diagnosis and allow more differentiated prognostic evaluations and genetic counseling of FH/FDB families. Previous genetic screening methods for FH have, however, been too cumbersome for routine use, however. To overcome these problems, we designed a mutation screening assay based on the highly sensitive denaturing gradient gel electrophoresis (DGGE) technique. The setup allows within 24 hr to pinpoint if and where a potential mutation is located in the LDLR promoter, the 18 LDLR gene exons and corresponding intronic splice site sequences, or in the codon 3500 region of apo B-100. The pinpointed region is subsequently sequenced. As an evaluation of the sensitivity, we demonstrated the ability of the assay to detect 27 different mutations or polymorphisms covering all the examined regions, except LDLR exon 16. In conclusion, a simple, but sensitive, clinically applicable mutation screening assay based on the DGGE principle may reveal the underlying mutation in most FH/FDB families and offer a tool for a more differentiated prognostic and therapeutic evaluation in FH/FDB.