Background— Screening for familial hypercholesterolemia (FH) within affected families is often based on cutoff values for low-density lipoprotein cholesterol (LDL-C). However, the diagnostic accuracy of LDL-C levels is influenced by the magnitude of the LDL-C overlap between FH patients and unaffected relatives. The purpose of the current study was to assess to what extent this overlap is influenced by the severity of specific FH mutations. Methods and Results— Individuals were eligible if they underwent family screening for FH between 2003 and 2010. The entire cohort was then compared with those who were investigated for the presence of the most severe mutations (class 1). The area under the receiver operating characteristics curve and the sensitivity of the 90th percentile of LDL-C were calculated for both cohorts. We included 26 406 individuals, of whom 9169 (35%) carried an FH-causing mutation. In the entire cohort at baseline, mean LDL-C was 4.63±1.44 mmol/L for FH carriers (n=5372) and 2.96±0.96 mmol/L for unaffected relatives (n=15 148); P<0.001. The corresponding operating characteristics curve (95% CI) was 86.6% (85.9%–87.2%), and the cutoff level of LDL-C above the 90th percentile showed a sensitivity of 68.5%. The operating characteristics curve and sensitivity significantly improved when the 5933 individuals tested for class 1 mutations were assessed separately; 96.2% (95.3%–97.1%) and 91.3%, respectively. Conclusions— In summary, the overlap in terms of LDL-C levels between those with molecularly proven FH and unaffected relatives is to a large extent because of the high prevalence of modestly severe LDL-receptor mutations in the Netherlands.

Background In the Netherlands, a screening programme was set up in 1994 in order to identify all patients with familial hypercholesterolaemia (FH). After 15 years of screening, we evaluated the geographical distribution, possible founder effects and clinical phenotype of the 12 most prevalent FH gene mutations. Methods Patients who carried one of the 12 most prevalent mutations, index cases and those identified between 1994 and 2009 through the screening programme and whose postal code was known were included in the study. Low-density lipoprotein cholesterol (LDL-C) levels at the time of screening were retrieved. The prevalence of identified FH patients in each postal code area was calculated and visualised in different maps. Results A total of 10,889 patients were included in the study. Mean untreated LDL-C levels ranged from 4.4 to 6.4 mmol/l. For almost all mutations, a region of high prevalence could be observed. In total, 51 homozygous patients were identified in the Netherlands, of which 13 true homozygous for one of the 12 most prevalent mutations. The majority of them were living in high-prevalence areas for that specific mutation. Conclusions Phenotypes with regard to LDL-C levels varied between the 12 most prevalent FH mutations. For most of these mutations, a founder effect was observed. Our observations can have implications with regard to the efficiency of molecular screening and physician’s perception of FH and to the understanding of the prevalence and distribution of homozygous patients in the Netherlands.

Niacin, the first lipid lowering drug shown to improve survival after myocardial infarction, decreases LDL and increases HDL cholesterol levels. These effects cannot fully be explained by its suspected mechanism of action, inhibition of lipolysis and hepatic VLDL synthesis. Niacin has also been shown to interfere with the cyclic AMP (cAMP)/protein kinase A (PKA) pathway and massively stimulate prostaglandin D2 (PGD2) formation. The major metabolite of PGD2, 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), was recently identified as the most potent endogenous PPARγ activator. We, therefore, studied the effects of niacin on the PPARγ- and cAMP-dependent expression of receptors promoting reverse cholesterol transport. The transcription of PPARγ-, HDL-, LDL- and scavenger-receptors and the sterol exporter ABCA1, were measured by quantitative RT-PCR and cellular cholesterol efflux and PPARγ activation studied in macrophage and hepatocyte models. Niacin stimulated the translocation of PPARγ and the transcription of PPARγ, CD36 and ABCA1 in monocytoid cells, whereas the LDL-receptor (LDL-R) was unchanged. Thereby niacin enhanced HDL-mediated cholesterol efflux from the cells resulting in a reduced cellular cholesterol content. The niacin effect on CD36 but not on ABCA1 was prevented by cyclooxygenase inhibition, whereas the niacin effect on ABCA1 but not on CD36 was prevented by PKA inhibition, suggesting mediation by the 15d-PGJ2/PPARγ and the cAMP/PKA pathways, respectively. These new actions of niacin on several key effectors of reverse cholesterol transport out of the vessel wall provide a rational to expect regression of atherosclerosis and test the combination of niacin with statins for an overadditive clinical benefit.

Objective : In this double-blind, randomized, placebo-controlled, dose-finding study we assessed the short-term efficacy and safety of increasing dosages of magnesium pyridoxal-5′-phosphate glutamate (MPPG) compared to placebo in patients with familial hypercholesterolaemia (FH). Twenty-three patients of either sex, over the age of 18 years and suffering from heterozygous FH, were treated with MPPG for a period of 16 weeks. Results: Baseline characteristics and lipoprotein profiles of the patients were comparable in the two treatment groups. Overall compliance was 90%. Neither after the first 8 weeks treatment period with 450 mg MPPG daily nor after the second 8 weeks treatment period with 600 mg MPPG daily were statistically significant changes in plasma total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol or triglyceride levels observed between the treatment and placebo groups. Plasma levels of lipoprotein (Lp)(a), apolipoprotein (apo) A 1 , apo B 100 , very low density lipoprotein (VLDL) cholesterol and VLDL triglyceride also did not change. Conclusion: Although it has been demonstrated that MPPG improves lipoprotein levels in patients with different forms of dyslipidaemia, MPPG is not effective for the treatment of FH patients.