Related Experiment Videos
Phenotype expression in familial combined hyperlipidemia
K V Porkka1, I Nuotio, P Pajukanta
1Department of Medicine, HUCH, University of Helsinki, Finland. kimmo.porkka@muikku.huch.fi
Insights
Familial combined hyperlipidaemia (FCHL) diagnosis depends heavily on chosen criteria, impacting affected percentages. Re-evaluating diagnostic standards for FCHL is crucial for accurate identification.
Area of Science:
- Genetics
- Metabolic Disorders
- Cardiovascular Disease
Background:
- Familial combined hyperlipidaemia (FCHL) is a common hereditary disorder linked to early coronary death.
- Affected individuals exhibit elevated serum total cholesterol, triglycerides, or both.
- The underlying genetic and metabolic defects of FCHL remain largely unknown.
Purpose of the Study:
- To investigate the influence of diagnostic criteria on phenotype definition in FCHL.
- To identify factors affecting phenotype expression in Finnish FCHL families.
- To explore potential reliable metabolic markers for FCHL diagnosis.
Main Methods:
- Analysis of 16 large Finnish families (n=255) with FCHL.
- Assessment of diagnostic criteria using different percentile cut-points (90th vs. 95th).
- Lipoprotein particle analysis (VLDL, IDL, LDL, HDL) via ultracentrifugation.
- Linkage analysis to identify genetic associations.
Main Results:
- The choice of percentile cut-points significantly altered FCHL diagnosis rates (45% with 90th vs. 22% with 95th).
- No single ultracentrifugation variable reliably distinguished affected from non-affected family members.
- Linkage analysis did not identify a single discriminating variable.
Conclusions:
- Current diagnostic criteria for FCHL require re-evaluation due to their significant impact on phenotype definition.
- There is a need for a single, reliable metabolic marker for precise FCHL diagnosis.
- Understanding FCHL genetics and metabolism necessitates refined diagnostic approaches.
Abstract:
Familial combined hyperlipidaemia (FCHL) is one of the most common hereditary disorders predisposing to early coronary death. The affected family members have elevations of serum total cholesterol, triglycerides or both. Despite intensive research efforts the genetic and metabolic defects underlying this complex disorder are still unknown. To dissect the metabolism and genetics of FCHL the phenotype of an individual must be precisely defined. We assessed the influence of different diagnostic criteria on the phenotype definition and studied factors affecting the phenotype expression in 16 large Finnish families (n = 255) with FCHL. The fractile cut-points used to define abnormal lipid values had a profound influence on the diagnosis of FCHL. If the 90th percentile cut-point was used, approximately 45% of the family members were affected, in concord with the presumed dominant mode of transmission for FCHL. If the 95th percentile was used only 22% of study subjects were affected. To characterize the metabolic differences or similarities between the different lipid phenotypes, we determined very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) particles separated by ultracentrifugation. In linkage analysis no single ultracentrifugation variable could discriminate reliably affected family members from non-affected family members. Our data emphasizes the need for re-evaluation of FCHL diagnostic criteria. Preferably, the diagnosis should be based on a single, reliable metabolic marker.