Phenotypic variation among familial hypercholesterolemics heterozygous for either one of two Afrikaner founder LDL receptor mutations

Two common founder-related gene mutations that affect the low-density lipoprotein receptor (LDLR) are responsible for approximately 80% of familial hypercholesterolemia (FH) in South African Afrikaners. The FH Afrikaner-1 (FH1) mutation (Asp206-->Glu) in exon 4 results in defective receptors with approximately 20% of normal activity, whereas the FH Afrikaner-2 (FH2) mutation (Val408-->Met) in exon 9 completely abolishes LDLR activity (< 2% normal activity). We analyzed the contribution of these mutations and other factors on the variation of hypercholesterolemia and clinical features in Afrikaner FH heterozygotes. The type of FH mutation, plasma triglyceride levels, and age of patients each contributed significantly to the variation in hypercholesterolemia, whereas smoking status, high-density lipoprotein cholesterol levels, and gender had no influence. Although all FH heterozygotes had frank hypercholesterolemia, patients with the FH1 mutation had significantly lower cholesterol levels than those with the FH2 mutation. FH1 heterozygotes also tended to have milder clinical features. The differences between the two FH groups could not be explained by a difference in the common apolipoprotein E variants. This study demonstrates that mutational heterogeneity in the LDLR gene influences the phenotypic expression of heterozygous FH.     

Incidence of familial defective apolipoprotein B-100 in cases of patients diagnosed with familial hypercholesterolemia

Familial Hypercholesterolemia (FH) and Familial Defective Apolipoprotein B-100 (FDB) are monogenic, autosome, dominantly inherited diseases appearing as type II/a primary hypercholesterolemia. The frequency of the heterozygositic forms is 1:700-1:500 in European population. Both forms of hypercholesterolemia causes early onset coronary heart diseases (CHD). According to the recommendations of the international MED-PED program (Make Early Diagnoses--Prevent Early Death), we found 73 FH cases and their 377 first relatives (parents, siblings, children) were also assessed. 156 patients were diagnosed clinically FH (131 alive and 25 deceased), and 31.8% of the males and 32.4% of females suffered from early onset CHD. One family with FH consists of 5.46 members on the average and there are 2.39 FH patients in one family. In our FH cohort four patients with FDB (R3500Q mutation) were diagnosed with allelspecific PCR, and the mutation was detectable also in 9 cases out of 11 living family members. The plasma total cholesterol level of the FDB patients--especially at younger age--was very close to the normal values, which is in contrast to the findings in FH patients. Nevertheless, FDB can be one of the independent causes of the early onset CHD. Therefore, in families with high frequency of cardiovascular diseases the R3500Q mutation has to be considered.     

Angiotensin-converting enzyme DD genotype and cardiovascular disease in heterozygous familial hypercholesterolemia

BACKGROUND: Controversy exists as to whether the deletion/deletion genotype (DD) of the ACE gene polymorphism increases the risk of myocardial infarction (MI). Studies have suggested that the ACE DD genotype is associated with increased plaque instability. We hypothesized that the ACE DD genotype may increase the risk of myocardial infarction and coronary heart disease (CHD) in patients with heterozygous familial hypercholesterolemia (FH) or familial defective apolipoprotein B-100 (FDB) who, as a group, are at high risk of having lipid-rich plaques in their coronary arteries. METHODS AND RESULTS: We determined the ACE genotypes and incidence of MI or surgical intervention for CHD in 213 adult patients with heterozygous FH or FDB. The incidence of MI in 35 male patients who carried the ACE DD genotype was 2.5 times that observed in male patients with the II or DI genotypes, and the incidence of CHD in male patients with the DD genotype was 2.2 times higher than in those who had ACE DI+II. The potential effects of ACE genotype on CHD could not be directly compared in female patients because of a disparity in the smoking history of the genotypic groups. From logistic regression analysis, the estimated odds ratio associated with the ACE DD genotype was 2.57 for MI and 2.21 for CHD adjusted for age, sex, and smoking history. CONCLUSIONS: The ACE DD genotype is associated with an increased risk of MI and CHD in patients with heterozygous FH or FDB. Determination of the ACE genotype in asymptomatic FH and FDB patients provides an additional means to identify those patients at greatest risk for the premature development of CHD.     

The impact of consanguinity and inbreeding on perinatal mortality in Karachi, Pakistan

Abnormal interaction between low density lipoprotein receptors (LDLR) and their ligands, apolipoprotein E and B, causes decreased catabolism of lipoproteins which carry these apolipoproteins (VLDL, IDL and/or LDL) and thereby increased plasma concentrations of these. In familial hypercholesterolemia (FH), abnormal interaction is due to mutations in the LDLR gene, and in type III hyperlipidemia due to mutations in the apo E gene. A few mutations in the apolipoprotein B (apo B) gene have been described, of which the apo B-3,500Arg-Gln seems by far the most frequent, that causes defective binding to normal LDLR. The metabolic disorder associated with these mutations has been named familial defective apolipoprotein B-100 (FDB). The frequency of the apo B-3,500Arg-Gln mutation is particularly high in Central Europe (Switzerland) with lower frequencies south of the Alpes, in Russia and in Scandinavia. We found an incidence of 1/1250 of the mutation in Denmark (III), employing a DNA based assay optimized to allow detection of the mutation in very small amounts of DNA (I). Since other mutations in the receptor binding domain of the apo B-100 have been described, we developed another DNA based assay, employing DGGE technique, to screen for other mutations in the region of amino acid 3,456 to 3,553 (II). However, no other mutations but the apo B-3,500Arg-Gln have so far been detected in Danish hypercholesterolemic patients. In a study of 5 Danish families with FDB (46 heterozygous FDB patients and 57 unaffected relatives) we found that FDB patients had significantly increased mean cholesterol and LDL cholesterol concentrations, but with a wide range of variation and with approximately 30% having cholesterol concentrations below the 95th percentile for the general population (IV). This was confirmed in a compilation of data on 205 FDB patients from the Netherlands, Germany and Denmark (V). In this study we also compared the biochemical and clinical features of FDB with those of 101 Danish FH patients in whome FDB had been ruled out. Our data support, that the LDL cholesterol elevation is less pronounced in FDB than in FH and that the age-specific prevalence of atherosclerotic cardiovascular disease (CVD) is lower in FDB than in FH. In the compiled study of 205 FDB heterozygotes (V), we found that age, gender and genetic variation in the LDLR gene explained a considerable part of the between-individual variation in total and LDL cholesterol. We conducted a prospective study of the lipid lowering effect of pravastatin and gemfibrozil in 30 Danish FDB patients (VI). Together with other, retrospective, studies, we conclude that the cholesterol lowering effect of HMG-coA-reductase inhibitors, anion binding resins and nicotinic acid is fully comparable to that observed when treating FH patients and type IIa hypercholesterolemic patients, without clinical signs of FH.     

Screening for known mutations in the LDL receptor gene causing familial hypercholesterolemia

Familial hypercholesterolemia (FH) is caused by defective low density lipoprotein (LDL) receptors and is characterized by hypercholesterolemia and premature coronary heart disease. Two strategies can be used to identify the mutation in the LDL receptor gene underlying FH. One strategy is to search for novel mutations by DNA sequencing with or without prior mutation screening. The other strategy is to screen for known mutations. In this study we employed the latter strategy to screen 75 unrelated, Norwegian FH subjects for 38 known mutations. Three of the 38 mutations were detected in our group of FH subjects. Two subjects had FH-Padova, one had FH-Cincinnati-2 and one had FH-Gujerat. When additional unrelated FH heterozygotes were screened for the three mutations, the gene frequencies were 1.3%, 1.0% and 3.0%, respectively. In addition to identifying known mutations we also detected a novel stop codon in codon 541 (S541X). We conclude that screening for known mutations in the LDL receptor gene should be used as a complementary strategy to screening for novel mutations in order to understand the molecular genetics of FH.     

Evaluation of tire-derived fuel for use in nitrogen oxide reduction by reburning

BACKGROUND: Recently, a mutation in the lipoprotein lipase (LPL) gene (N291S) has been reported in 2% to 5% of individuals in western populations and is associated with increased triglyceride (TG) and reduced HDL cholesterol (HDLC) concentrations. METHODS AND RESULTS: Here we report a significant alteration in biochemical and clinical phenotype in subjects with familial hypercholesterolemia (FH) who are heterozygous for this N291S LPL mutation. Sixty-four FH heterozygotes carrying the N291S mutation had significantly a higher TG level (P=.004), a higher ratio of total cholesterol to HDLC (P<.001), and lower HDLC concentrations (P=.002) compared with 175 FH heterozygotes without this LPL mutation. Moreover, the N291S mutation conferred a significantly greater risk for developing cardiovascular disease in FH heterozygotes compared with FH heterozygotes without this LPL mutation (odds ratio, 3.875; P=.006). CONCLUSIONS: These data provide evidence that a common LPL variant (N291S) significantly influences the biochemical phenotype and risk for cardiovascular disease in patients with FH.     

Immune reconstitution following transplantation of selected hematopoietic stem cells

We have evaluated whether low density lipoprotein (LDL) receptor activity of stimulated lymphocytes, as measured by an improved flow cytometric assay, may be used to diagnose familial hypercholesterolemia (FH). Cells were isolated from 75 children suspected from strict clinical criteria to be FH heterozygotes and from 29 normal children. DNA from the FH patients were also subjected to molecular genetic analysis of the LDL receptor gene in order to confirm the clinical diagnosis. A molecular genetic diagnosis of FH was obtained in 68 of the 75 patients; 67 of these had a low (below 70% of normal) receptor activity and 1 had a borderline (71%) activity. By contrast, 28 of the normal children showed a normal (above 80%) and 1 a borderline (78%) receptor activity. Of the 7 patients in whom no mutation in the LDL receptor gene was found, 4 showed a normal, 1 a borderline, and 2 showed a low activity. In summary, measurement of LDL receptor activity allowed us to separate between genetically diagnosed FH heterozygotes and healthy children. The combined use of LDL receptor activity measurements and molecular genetic analysis allows us both to diagnose and exclude FH in children suspected to suffer from this disease.     

Sib-pair analysis detects elevated Lp(a) levels and large variation of Lp(a) concentration in subjects with familial defective ApoB

Whether or not Lp(a) plasma levels are affected by the apoB R3500Q mutation, which causes Familial Defective apoB (FDB), is still a matter of debate. We have analyzed 300 family members of 13 unrelated Dutch index patients for the apoB mutation and the apolipoprotein(a) [apo(a)] genotype. Total cholesterol, LDL-cholesterol, and lipoprotein(a) [Lp(a)] concentrations were determined in 85 FDB heterozygotes and 106 non-FDB relatives. Mean LDL levels were significantly elevated in FDB subjects compared to non-FDB relatives (P < 0.001). Median Lp(a) levels were not different between FDB subjects and their non-FDB relatives. In contrast, sib-pair analysis demonstrated a significant effect of the FDB status on Lp(a) levels. In sib pairs identical by descent for apo(a) alleles but discordant for the FDB mutation (n = 11) each sib with FDB had a higher Lp(a) level than the corresponding non-FDB sib. Further, all possible sib pairs (n = 105) were grouped into three categories according to the absence/presence of the apoB R3500Q mutation in one or both subjects of a sib pair. The variability of differences in Lp(a) levels within the sib pairs increased with the number (0, 1, and 2) of FDB subjects present in the sib pair. This suggests that the FDB status increases Lp(a) level and variability, and that apoB may be a variability gene for Lp(a) levels in plasma.     

Neonatal diagnosis of familial hypercholesterolemia in newborns born to a parent with a molecularly defined heterozygous familial hypercholesterolemia

This study was designed to compare blood lipid levels in newborn individuals with molecularly defined heterozygous familial hypercholesterolemia [FH] to those in non-affected babies and to clarify the value of lipid determinations in assessment of diagnosis of FH at birth and 1 year of age. Twenty-five babies were born to 21 parents with DNA-documented heterozygous FH. Analysis of their cord blood samples revealed 11 newborns with the FH-North Karelia [FH-NK] mutation, 3 newborns with the FH-Helsinki [FH-HKI] mutation, and 11 nonaffected newborns. Cord serum total [TC] and LDL cholesterol [LDL-C] levels (mean +/- SD) in affected newborns (2.60 +/- 0.70 and 1.77 +/- 0.56, respectively) were significantly (P < .001) higher than those in nonaffected ones (1.54 +/- 0.23 and 0.78 +/- 0.15, respectively) and another cohort of 30 randomly selected control samples from apparently healthy newborns (1.84 +/- 0.46 and 1.03 +/- 0.30, respectively). However, there was overlapping of individual lipid levels in these three groups precluding the use of TC or LDL-C determinations in neonatal diagnosis of FH. In contrast, 1 year follow-up samples from 10 affected and 7 nonaffected individuals, as well as additional samples collected from another group of 8 affected and 9 nonaffected individuals, indicated that serum cholesterol levels showed much greater increment in children with FH. Thus, at the age of 1 year the mean serum TC and LDL-C levels in the affected infants (8.38 +/- 1.18 and 7.02 +/- 1.07, respectively) were much higher (P < .001) than the corresponding levels (4.40 +/- 0.66 and 2.89 +/- 0.68, respectively) in the nonaffected infants, and the individual ranges of TC and LDL-C levels were nonoverlapping in these two groups. Serum HDL cholesterol [HDL-C] levels in 1-year-old children with FH (0.95 +/- 0.14) were approximately 20% lower than those of their similar at birth. In conclusion, phenotypic expression of heterozygous FH, as defined by molecular analysis of genomic DNA, is evident in serum LDL-C (but not HDL-C) levels already at birth, but for diagnostic purposes blood lipid determinations carried out at the age of 1 year are highly superior to those performed at birth.     

Improved detection of familial hypercholesterolemia by determining low density lipoprotein receptor expression in mitogen-induced proliferating lymphocytes

In view of the presence of some 190 mutations in the low density lipoprotein receptor (LDL-R) gene and a lack of simple detection methods, we have developed an improved assay system for detecting familial hypercholesterolemia (FH) using mitogen-induced proliferating lymphocytes. Freshly isolated mononuclear cells were cultured for 3 days in RPMI 1640 supplemented with 10% human lipoprotein-deficient serum (LPDS) and 1% phytohemagglutinin (PHA). LDL-R expression was measured by flow cytometry using a monoclonal anti-LDL-R antibody or DiI-LDL. Mitogenic responses were monitored by cell size (FSC), interleukin-2 receptor (IL2-R) expression, and stimulation index (SI). The LDL-R expression in PHA-stimulated lymphocytes was significantly higher than lymphocytes or monocytes cultured without PHA (15.2- and 3.6-fold, respectively). The gradation of the LDL-R expression was highly correlated to FSC, IL2-R expression, and SI (r > 0.9 in each case). However, no difference in FSC, IL2-R expression, or SI existed between 30 clinically diagnosed FH and 42 normolipemic control subjects. The significantly lower LDL-R expression in the FH group (45.2 +/- 15.3% versus 100 +/- 14.1%; unpaired t test, P < 0.0001) indicated the presence of genetic defects. Normocholesterolemic first degree relatives and non-FH hypercholesterolemic subjects demonstrated normal LDL-R expression as did the controls. The assay carries an efficiency of 97% and both sensitivity and specificity of 98.5%. Measurement of low density lipoprotein receptor expression in phytohemagglutinin- and lipoprotein-deficient serum-stimulated lymphocytes offers a simple method for detecting familial hypercholesterolemia with improved sensitivity.     

Reduced coronary flow reserve in familial hypercholesterolemia

Familial hypercholesterolemia (FH) presents the highest risk for coronary artery disease (CAD) among patients with hyperlipidemia. Therefore, early detection of coronary arterial atherosclerosis is important for the treatment of FH patients. The aim of this study was to detect early coronary arterial abnormalities that may relate to future atherosclerosis in asymptomatic FH patients by measuring coronary flow reserve (CFR) using PET and 13N-ammonia. METHODS: Twenty-five patients with FH (14 men, 11 women) without a history of myocardial ischemia and 14 control subjects (9 men, 5 women) were studied. Total serum cholesterol (mmole/liter) was 5.33 +/- 0.66 in control subjects and 7.90 +/- 0.77 in FH patients (p < 0.01 versus control subjects). RESULTS: Myocardial blood flow (MBF) at rest and during dipyridamole loading was measured using PET, and CFR was calculated. MBF (ml/min/100 g weight heart) at rest in the FH group (79.0 +/- 20.0) was comparable to that in control subjects (70.0 +/- 17.0). However, MBF during dipyridamole loading was significantly lower in FH patients (163.0 +/- 67.0) than in control subjects (286.0 +/- 120.0, p < 0.01). CFR in FH patients (2.09 +/- 0.62) was also significantly lower than that in control subjects (4.13 +/- 1.38, p < 0.01). CFR showed a gender-specific variance in FH patients (1.85 +/- 0.40 in men versus 2.55 +/- 0.74 in women p < 0.05) but not in control subjects. Significant inverse correlations between CFR and the total plasma cholesterol level as well as plasma LDL cholesterol were observed. CONCLUSION: The CFR was reduced in patients with FH. This abnormality was more prominent in men than in women patients. Noninvasive assessment of CFR by 13N-ammonia PET was useful to detect early abnormalities of the coronary arteries in asymptomatic patients with FH.     

Elevated levels of lipoprotein (a) in children with familial hypercholesterolemia

Lipoprotein(a)[Lp(a)] concentrations and their correlation to total cholesterol (TC), low-density and high-density lipoprotein cholesterol (LDL-C, HDL-C) and triglycerides (TG) were estimated in 20 normal weight children affected with familial hypercholesterolemia (FH) and for comparison in 20 overweight, but otherwise healthy children, matched for sex and age. The mean value of Lp(a) in patients with FH (0.29 g/l, SD = 0.27) was markedly higher than in the control group (0.17g/l, SD = 0.19), but the difference was not statistically significant. However, the frequency distribution of Lp(a) in both groups was different: the proportion of Lp(a) levels above 0.60g/l was significantly greater in patients with FH than in the controls (p < 0.05). These results indicate that even pediatric patients with FH have increased Lp(a) levels. Since Lp(a) elevation above 0.25 to 0.30g/l--in particular in combination with increased LDL concentrations--is is associated with a markedly increased risk of coronary heart disease, cervical atherosclerosis and cerebral infarction, it seems very important to detect these high-risk individuals as early as possible and to treat them appropriately.     

Genetic variation at the apoA-IV gene locus and response to diet in familial hypercholesterolemia

Plasma lipid response to dietary fat and cholesterol is, in part, genetically controlled. The apolipoprotein A-IV (apoA-IV protein; APOA4, gene) has been shown to influence the response to dietary changes in normolipidemic individuals. The response to diet in subjects with familial hypercholesterolemia (FH) is also variable, and no studies are available on the influence of APOA4 mutations on dietary response in these subjects. We studied the effect of 2 common apoA-IV genetic variants (Gln360-->His and Thr347-->Ser) on the lipid response to the National Cholesterol Education Program type I (NCEP-I) diet in 67 FH heterozygotes (43 women and 24 men). Subjects were studied at baseline (after consuming for 1 month a diet with 35% fat [10% saturated] and 300 mg/d cholesterol) and after 3 months of consuming a low-fat diet. No sex-related differences were found, and results were combined for men and women. The APOA4-360 mutation was assessed in 67 subjects, 51 with genotype 1/1 and 16 with genotype 1/2. The APOA4-2 allele was associated with marginally significantly lower (P=0.049) low density lipoprotein (LDL) cholesterol levels and significantly lower (P=0.027) apoB levels independent of diet effects. After consuming an NCEP-I diet, carriers of the APOA4-2 allele showed a significantly lower reduction in apoB concentration (6.2%) than 1/1 subjects (14.1%; P=0.036); however, no significant differences in response were noted for LDL cholesterol. The APOA4-347 mutation was assessed in 63 individuals, 44 with the A/A allele and 19 with the A/T and T/T alleles. No significant differences were observed in baseline or post-NCEP-I diet values for these 2 groups in total, LDL, and high density lipoprotein cholesterol and plasma apoB levels. After dietary intervention, A/A individuals showed significant reductions in plasma triglyceride and very low density lipoprotein cholesterol levels; no changes were found in carriers of the T allele. Haplotype analysis suggested that in these FH subjects, the APOA4-360-2 allele was associated with lower plasma lipid levels during the NCEP-I diet period, whereas no significant effects were observed for the APOA4-347-T allele.     

Low density lipoprotein receptor mutations in a selected population of individuals with moderate hypercholesterolemia

To evaluate mutations in the low density lipoprotein receptor (LDL-R) gene in moderate primary hypercholesterolemia, a combination of polymerase chain reaction (PCR), single-strand conformation polymorphism (SSCP) and direct sequencing, was used to screen the LDL-R gene in a selected population of 82 unrelated individuals with moderate elevation of plasma LDL-C [mean 4.55 +/- 0.55 mmol/l (176.4 +/- 21.6 mg/dl)]. Four subjects (5%) were found to be heterozygotes for missense mutations in the LDL-R gene. These mutations were located in four different exons (exons 6, 7, 15 and 17) and all alters highly conserved residues of LDL-R protein. None of these mutations were detected in 79 normocholesterolemic individuals. The mutation in exon 15 (T705I) was previously reported in a compound heterozygote for familial hypercholesterolemia (FH). In the proband carrying the mutation in exon 17 (R793Q), an in vivo LDL turnover study was performed and it demonstrated a reduction of LDL catabolism. These findings demonstrate that mutations in the LDL-R may occur in primary moderate hypercholesterolemia. They also extend the concept that some FH patients may present with a mild phenotype.     

E-test to study small inhibitor concentrations, bacterial diversity and to identify presumptively beta-lactamases in strains of Pseudomonas aeruginosa and Acinetobacter baumannii associated with +nosocomial infections

The objectives of the present study were to characterize the surface expression of low density lipoprotein receptor (LDL-R) in Epstein-Barr virus transformed lymphocytes (EBV-L) and to determine the applicability of the cellular system for the study of familial hypercholesterolemia. The EBV-L subsets and LDL-R expression were determined by immuno-cytofluorimetry. The LDL-R expression in EBV-L which consisted of mostly B cells was no different among antigenic subsets. EBV-L cultured in lipoprotein deficient serum demonstrated a 9.3-fold higher LDL-R expression than primary lymphocytes. Lovastatin caused an additional 1.9-and 1.4-fold increase in EBV-L and primary lymphocytes respectively. This difference in lovastatin response is statistically significant (paired t-test, P < 0.001). 54% of the high LDL-R expression in EBV-L was related to the changes in proliferation measured as stimulation index (SI). LDL and lovastatin modulated the LDL-R expression without affecting SI. FH subjects demonstrated 2% (homozygote, n = 1) and 44.6 +/- 12.3% (heterozygotes, n = 35) in LDL-R expression of controls (n = 30). This maintenance of the FH phenotype and the intrinsically high LDL-R expression in EBV-L make the cellular system suitable for the study of FH as well as the regulation of LDL-R.     

Ambulatory blood pressure and Holter monitoring of emergency physicians before, during, and after a night shift

BACKGROUND: Patients with a mutation in the LDL receptor gene (familial hypercholesterolemia, or FH) are characterized by substantial elevations in plasma LDL cholesterol and are at higher risk of developing coronary artery disease (CAD). Correlates of abdominal obesity may also contribute to the risk of ischemic cardiac events. Whether the hyperinsulinemic-insulin-resistant state of abdominal obesity affects coronary atherosclerosis among FH patients has not been determined. METHODS AND RESULTS: The relation of abdominal adiposity and hyperinsulinemia to angiographically assessed CAD was evaluated in a sample of 120 French Canadian men aged <60 years who were heterozygotes for FH and in a group of 280 men without FH. In the present study, the risk of CAD associated with abdominal obesity, as estimated by the waist circumference, was largely dependent on the concomitant variation in plasma lipoprotein and insulin concentrations. In contrast, the association between fasting insulin and CAD was independent of variations in waist girth, triglyceride, HDL, and apolipoprotein B concentrations (odds ratio, 1.86; P=.0005). However, the most substantial increase in the risk of CAD was observed among abdominally obese (waist circumference >95 cm) and hyperinsulinemic FH patients (odds ratio, 12.9; P=.0009). This increase in risk remained significant even after adjustment for LDL cholesterol or apolipoprotein B concentrations. CONCLUSIONS: Results of the present study provide support for the notion that the hyperinsulinemic-insulin-resistant state of abdominal obesity is a powerful predictor of CAD in men, even in a group of patients with raised LDL cholesterol concentrations due to FH.     

Flow cytometry with a monoclonal antibody to the low density lipoprotein receptor compared with gene mutation detection in diagnosis of heterozygous familial hypercholesterolemia

We used a fluorescence flow cytometry assay with a monoclonal low density lipoprotein (LDL) receptor-specific antibody to detect LDL receptor expression on blood T lymphocytes and monocytes. We prepared peripheral blood mononuclear cells from patients with genetically verified LDL receptor-defective (Trp66-Gly mutation, n = 17) or receptor-negative (Trp23-stop mutation, n = 17) heterozygous familial hypercholesterolemia (FH) and from healthy individuals (n = 24). The cells were stimulated to express the maximum amount of LDL receptor by preincubation in lipoprotein-deficient medium. A dual-labeling technique allowed flow cytometric analysis of LDL receptor expression on cells identified by fluorescently conjugated surface marker antibodies. Knowing the LDL receptor gene mutation of the FH patients allowed us to compare the diagnostic capability of this functional assay with the DNA diagnosis and to validate the assay with molecular genetics instead of clinical indices of heterozygous FH. T lymphocytes expressed more LDL receptors and gave better diagnostic results than monocytes, and cells from patients with either the Trp66-Gly or the Trp23-stop mutation had variable but significantly reduced LDL receptor expression. The data indicate that this fluorescence flow cytometry assay is unsuitable for diagnosis of individual cases of heterozygous FH but that it may be useful for functionally characterizing mutations in the LDL receptor gene.     

Use of cholestyramine in the treatment of children with familial combined hyperlipidemia

We studied the effectiveness of and compliance with the use of cholestyramine in children with heterozygous familial hypercholesterolemia (FH) and familial combined hyperlipidemia (FCHL). During a 10-year period, 673 children (aged 10.5 +/- 4.0 years) were referred for evaluation of hyperlipidemia, of whom 87 (36 with FH; 51 with FCHL) were treated with cholestyramine (8 to 24 gm/day). In both groups, total cholesterol, low-density lipoprotein (LDL)-cholesterol, and apolipoprotein B levels were significantly reduced after cholestyramine use. In those with FH, plasma LDL-cholesterol levels decreased from 258 +/- 35 mg/dl (6.67 +/- 0.90 mmol/L) to 190 +/- 31 mg/dl (4.91 +/- 0.80 mmol/L); in those with FCHL, LDL-cholesterol levels dropped from 207 +/- 40 mg/dl (5.35 +/- 1.03 mmol/L) to 141 +/- 35 mg/dl (3.64 +/- 0.90 mmol/L). High-density lipoprotein-cholesterol levels were not significantly changed after cholestyramine use in either group. In the FCHL group, plasma triglyceride levels increased significantly from 81 +/- 35 mg/dl (0.92 +/- 0.40 mmol/L) to 134 +/- 42 mg/dl (1.52 +/- 0.48 mmol/L). Seven patients were lost to follow-up; 18 discontinued the medication within 1 month. Of the remaining 62 children, 59 had a good response to the drug. Of the 62 patients, 52 discontinued the medication after 21.9 +/- 10 months. Adverse effects included foul taste (73%), nausea with bloating (18%), and constipation. Cholestyramine is effective in reducing LDL-cholesterol levels in children with inherited hyperlipidemia, but the majority of children will not comply with its long-term use.     

Atorvastatin: an effective lipid-modifying agent in familial hypercholesterolemia

Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are the drugs of choice in heterozygous familial hypercholesterolemia (FH), which has a high risk of ischemic heart disease. An open-label study was conducted to test the efficacy and safety of atorvastatin, a new synthetic HMG-CoA reductase inhibitor in proven FH. After a 4-week placebo phase, 22 subjects were randomized to either 80 mg atorvastatin at night (n = 11) or 40 mg twice a day for 6 weeks. The two dosage groups were well matched and had no difference in lipoprotein responses. After 6 weeks, the LDL cholesterol concentration was reduced by 57%, from 8.16 +/- 1.15 to 3.53 +/- 0.99 mmol/L (P < .001). The total cholesterol concentration decreased from 9.90 +/- 1.32 to 5.43 mmol/L (P < .001). HDL cholesterol concentration increased from 1.19 +/- 0.31 to 1.49 +/- 0.43 mmol/L (P < .001). Triglyceride concentrations decreased from 1.34 +/- 0.66 to 0.88 +/- 0.36 mmol/L (P < .01). Three subjects had single, transient increases of serum transaminase of up to twice the upper limit of normal. Apolipoprotein B concentration decreased significantly by 42%. Changes in apolipoproteins AI and (a) were not statistically significant. Nondenaturing gradient gel electrophoresis revealed increases in the size of smaller LDL particles in four subjects. Plasma fibrinogen concentration increased by 44%. The drug was well tolerated. One subject withdrew for personal reasons. Atorvastatin is a powerful and safe lipid-modifying agent for LDL cholesterol; it also modifies HDL cholesterol and triglyceride concentrations, and may suffice as a single agent for many subjects with heterozygous FH.     

Analysis of LDL receptor gene mutations in Italian patients with homozygous familial hypercholesterolemia

The aim of this study was the characterization of mutations of the LDL receptor gene in 39 Italian patients with homozygous familial hypercholesterolemia, who were examined during the period 1994 to 1996. The age of the patients ranged from 1 to 64 years; one third of them were older than 30. Plasma LDL cholesterol level ranged from 10.8 to 25.1 mmol/L. The residual LDL receptor activity, measured in cultured fibroblasts of 32 patients, varied from <2% to 30% of normal and was inversely correlated with the plasma LDL cholesterol level (r=-0.665; P<0.003). The most severe coronary atherosclerosis was observed in those patients with the lowest residual LDL receptor activity (相似文献