Comparison of effects of simvastatin versus atorvastatin on high-density lipoprotein cholesterol and apolipoprotein A-I levels.
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Anticholesteremic Agents↗
Biomedical subjects
L Ose
Publications and source records attributed to L Ose.
Lipid-altering efficacy and safety of simvastatin 80 mg/day: long-term experience in a large group of patients with hypercholesterolemia. World Wide Expanded Dose Simvastatin Study Group.
BACKGROUND: Elevated levels of low-density lipoprotein (LDL) cholesterol promote the development of atherosclerosis and coronary heart disease. HYPOTHESIS: Simvastatin 80 mg/day will be more effective than simvastatin 40 mg/day at reducing LDL cholesterol and will be well tolerated. METHODS: Two similar, randomized, multicenter, controlled, double-blind, parallel-group, 48-week studies were performed to evaluate the long-term lipid-altering efficacy and safety of simvastatin 80 mg/day in patients with hypercholesterolemia. One study conducted in the US enrolled patients meeting the National Cholesterol Education Program (NCEP) LDL cholesterol criteria for pharmacologic treatment. In the other multinational study, patients with LDL cholesterol levels > or = 4.2 mmol/l were enrolled. At 20 centers in the US and 19 countries world-wide, 1,105 hypercholesterolemic patients, while on a lipid-lowering diet, were randomly assigned at a ratio of 2:3 to receive simvastatin 40 mg (n = 436) or 80 mg (n = 669) once daily for 24 weeks. Those patients completing an initial 24-week base study were enrolled in a 24-week blinded extension. Patients who had started on the 80 mg dose in the base study continued on the same dose in the extension, while those who had started on the 40 mg dose were rerandomized at a 1:1 ratio to simvastatin 40 or 80 mg in the extension. RESULTS: There was a significant advantage in the LDL cholesterol-lowering effect of the 80 mg dose compared with that of the 40 mg dose, which was maintained over the 48 weeks of treatment. The mean percentage reductions (95% confidence intervals) from baseline in LDL cholesterol for the 40 and 80 mg groups were 41% (42, 39) and 47% (48, 46), respectively, for the 24-week base study, and 41% (43, 39) and 46% (47, 45), respectively, after 48 weeks of treatment (p < 0.001 between groups). Larger reductions in total cholesterol and triglycerides were also observed with the 80 mg dose compared with the 40 mg dose at Weeks 24 and 48. Both doses were well tolerated, with close to 95% of patients enrolled completing the entire 48 weeks of treatment. Myopathy (muscle symptoms plus creatine kinase increase > 10 fold upper limit of normal) and clinically significant hepatic transaminase increases (> 3 times the upper limit of normal) occurred infrequently with both doses. There was no significant difference between the groups in the number of patients with such increases, although there were more cases for both with the 80 mg dose. CONCLUSIONS: Compared with the 40 mg dose, simvastatin 80 mg produced greater reductions in LDL cholesterol, total cholesterol, and triglycerides. Both doses were well tolerated.
Adult↗
Does maternal or paternal heredity affect carotid atherosclerosis in children with familial hypercholesterolaemia?
Maternal hypercholesterolaemia has recently been shown to increase the number of fatty streaks in the foetal aorta, as well as subsequent progression of fatty streaks to more advanced lesions. We compared carotid intima-media thickness by B-mode ultrasonography in children who inherited familial hypercholesterolaemia from their mothers or fathers, hypothesizing that children whose mothers were hypercholesterolaemic during pregnancy had increased atherogenesis compared with children whose mothers did not have familial hypercholesterolaemia. We found that carotid intima-media thickness and prevalence of plaque did not differ between children with familial hypercholesterolaemia who inherited FH maternally or paternally.
Adolescent↗
A functional polymorphism in the promoter region of the microsomal triglyceride transfer protein (MTP -493G/T) influences lipoprotein phenotype in familial hypercholesterolemia.
The microsomal triglyceride transfer protein (MTP) has a key function in intracellular apolipoprotein (apo) B lipidation and secretion of very low density lipoprotein (VLDL). A recently discovered functional polymorphism in the promoter of the MTP gene (-493G/T) affects the plasma concentration of low density lipoprotein (LDL) cholesterol and the VLDL distribution between large and small particle species in healthy men. This phenotype is likely to be explained by an effect on VLDL synthesis. Against this background, we studied the effect of the MTP-493G/T polymorphism in a large cohort (217 men and 211 women) with heterozygous familial hypercholesterolemia (FH). A 40% to 50% lower serum triglyceride level was observed in homozygous carriers of the MTP-493 T allele (T/T, 0.93+/-0.34; G/T, 1.54+/-1.40; and G/G, 1.56+/-1.24 mmol/L; T/T vs G/T P=0.04, T/T vs G/G P=0.02). In contrast to the situation in healthy subjects, the MTP promoter polymorphism did not have a significant effect on the LDL cholesterol levels in FH subjects, although the same trend was observed (T/T, 7.31+/-1.87; G/T, 7. 80+/-2.12; and G/G, 7.91+/-2.31 mmol/L, NS). Adjustment for the apo E gene polymorphism by inclusion of subjects homozygous for the apo E3 allele only revealed a reciprocal high density lipoprotein cholesterol-elevating effect (T/T, 1.41+/-0.73; G/T, 1.18+/-0.27; and G/G, 1.16+/-0.29 mmol/L; T/T vs G/T P=0.06, T/T vs G/G P=0.04). This effect seemed to be sex-specific because it was accounted for by the female patients. In conclusion, the LDL cholesterol-lowering effect of the rare MTP gene promoter variant (MTP-493T) present in healthy subjects is shifted to a triglyceride-lowering effect in FH. These data suggest that the MTP gene has a role in modulating the clinical phenotype of FH.
Adolescent↗
Cerivastatin gender effect: sub-analyses of results from a multinational, randomised, double-blind study. Cerivastatin Study Group.
We previously reported the results of a multicentre, randomised, double-blind, parallel-group study comparing the efficacy and safety of cerivastatin 0.4 mg/day and cerivastatin 0.2 mg/day in patients with primary hypercholesterolaemia. Exploratory analysis in this study suggested a gender difference in the 0.4 mg group: mean low-density lipoprotein cholesterol (LDL-C) decreased by 44.4 +/- 8.9% in women, compared with a mean decrease of 37.0 +/- 0.9% in men (p < 0.046). This paper reports the results of further sub-analyses from this study. Overall in the per-protocol (PP) population, 71.5% (n = 73) of women taking cerivastatin 0.4 mg had an LDL-C decrease of > 40%, compared with 38.0% (n = 76) of men taking the same dose. In the cerivastatin 0.2 mg PP population, 34% (n = 17) of women had an LDL-C decrease of > 40%, compared with 19% (n = 18) of men. Mean LDL-C/HDL-C ratio decreased by 43% from baseline to the end of the study in the cerivastatin 0.4 mg PP group: -41.3% in males vs. -48.3% in females. In the cerivastatin 0.2 mg group, the decrease in LDL-C/HDL-C ratio from baseline to endpoint did not markedly differ between genders: -37.0% for males vs. -37.3% for females. Categorial analysis of the LDL-C/HDL-C ratio found that 90% of PP patients taking cerivastatin 0.4 mg, and 84% of PP patients taking cerivastatin 0.2 mg, had a low CHD risk (defined as a LDL-C/HDL-C ratio < or = 3) after 8 weeks of treatment. The 6th and 95th percentiles of the distribution of LDL-C reduction from baseline revealed that 90% of PP patients taking cerivastatin 0.4 mg had an LDL-C reduction of between 22% and 56%. The mean LDL-C reduction for this 90% subset of patients was 40.1%. The same analysis for PP patients taking cerivastatin 0.2 mg found that 90% had an LDL-C reduction of between 13% and 49%. The mean LDL-C reduction in this 90% subset of patients was 31.5%. Of the patients taking cerivastatin 0.4 mg and valid for treatment according to National Cholesterol Education Program (NCEP) criteria, 71% (149/211) achieved NCEP targets for LDL-C at Week 16.
Adult↗
Application of simple lipid treatment goals in patients with atherosclerotic disease.
BACKGROUND AND AIM: In this multicentre observational study the "5-4-3-2-1" guideline (total cholesterol < 5.0 mmol/L, the ratio of total to high-density lipoprotein cholesterol < 4, low-density lipoprotein cholesterol < 3.0 mmol/L, triglycerides < 2.0 mmol/L and high-density lipoprotein cholesterol > 1.0 mmol/L) was compared with the new European recommendations (total cholesterol < 5.0 mmol/L and low-density lipoprotein cholesterol < 3.0 mmol/L) ("5-3") and a treatment criterion of low-density lipoprotein cholesterol < 3.0 mmol/L and triglycerides < 1.5 mmol/L ("3-1.5"), as patients with triglycerides > 1.5 mmol/L may have an increased risk of premature cardiovascular disease. METHODS AND RESULTS: In 1997/98, 2134 patients in general practice with established atherosclerotic disease on a lipid-lowering therapy were monitored. The "5-4-3-2-1" guideline was met in 19.2% and the "5-3" guideline in 36.2% and 22.5% fulfilled the "3-1.5" criterion. Our data showed a good conformity between the "5-4-3-2-1" guideline and the "3-1.5" criterion. Of the patients who achieved the "5-3" guideline approximately 50% still had unfavourable values of HDL-cholesterol and TG, while only 15% of those who fulfilled the "3-1.5" criterion had HDL-cholesterol < or = 1.0 mmol/L. CONCLUSIONS: A treatment goal of LDL-cholesterol < 3.0 mmol/L and fasting TG < 1.5 mmol/L markedly raised the proportion of patients with desirable levels of HDL-cholesterol and the ratio of total cholesterol to HDL-cholesterol and should be recommended in secondary prevention, especially in diabetic patients.
Adult↗
Lipid-altering efficacy and safety of simvastatin 80 mg/day: worldwide long-term experience in patients with hypercholesterolemia.
BACKGROUND AND AIM: Clinical data suggesting that larger decreases in low density lipoprotein cholesterol (LDL-C) result in greater reductions in coronary heart disease events have led to the establishment of aggressive LDL-C targets for the treatment of hypercholesterolemia. In view of this, the efficacy and safety of a new maximum dose of simvastatin, 80 mg, were evaluated in 9 studies involving 2819 hypercholesterolemic patients. This report focuses on the combined results from the 4 main or Pivotal studies in which a total of 1936 patients received simvastatin 40 or 80 mg for 36 to 48 weeks. METHODS AND RESULTS: The Pivotal studies had similar randomized, multicenter, controlled, double-blind, parallel-group designs. Their combined results demonstrated a significant advantage in the LDL-C-lowering effect for the 80 mg dose. At week 24, the mean percentage reductions (95% confidence intervals) from baseline in LDL-C for the 40 and 80 mg groups were -39.8% (-40.9, -38.7) and -45.7% (-46.5, -45.0) respectively (p < 0.001, between groups), and larger reductions in total cholesterol and triglycerides were also observed in the 80 mg group. Both doses were well tolerated. No new or unexpected adverse events were observed and the overall clinical event profiles were similar in the two groups. Clinically significant hepatic transaminase increases (> 3 times the upper limit of normal/ULN) and myopathy (muscle symptoms plus creatine kinase increase > 10 times ULN) occurred infrequently with both doses. Simvastatin 80 mg had a comparable efficacy and safety profile in women and men as well as in non-elderly and elderly patients. CONCLUSIONS: Simvastatin 80 mg provides additional LDL-C and triglyceride reductions compared to the 40 mg dose and has an excellent safety and tolerability profile.
Adolescent↗
Effect of Norwegian fish powder on risk factors for coronary heart disease among hypercholesterolemic individuals.
BACKGROUND AND AIM: Numerous studies suggest an association between high intake of fatty fish and reduced risk of coronary heart disease. Very long-chain omega-3 fatty acids are thought to be responsible for the benefits observed, though other fatty fish components may act in concert with them. Norwegian fish powder is a dry herring product that contains essential amino acids, marine omega-3 fatty acids, vitamins and minerals. The aim of the present study was to determine whether it has beneficial effects on risk factors for coronary heart disease in man. METHODS AND RESULTS: A single center, randomized, double-blind, parallel-treatment study was carried out for 12 weeks. Subjects with primary hypercholesterolemia were randomly allocated to 10 g fish powder or placebo (20 tablets/day). Participants were instructed to follow National Cholesterol Education Program (NCEP) Step I Diet during a 4-week diet run-in phase and during the study. Concentrations of lipids, lipoproteins, hemostatic variables and endothelial cell markers were determined before and after supplementation. Our data showed that the fish powder supplement was well tolerated. A significant decrease and increase respectively were observed in plasma alpha-linolenic acid (p = 0.03) and docosahexaenoic acid (DHA) (p = 0.03). Concentrations of lipids, lipoproteins, homocysteine, factor VII, fibrinogen, tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI)-1, soluble intercellular adhesion molecule (ICAM)-1, P-selectin and interleukin (IL)-8 were not beneficially affected. CONCLUSIONS: Fish powder supplementation does not seem an effective approach to improve risk factors for coronary heart disease in hypercholesterolemic subjects following the NCEP Step I Diet.
Adult↗
Effects of high doses of simvastatin and atorvastatin on high-density lipoprotein cholesterol and apolipoprotein A-I.
A randomized, blinded, multicenter clinical trial was performed comparing low- and high-dose simvastatin (40 and 80 mg) with comparable doses of atorvastatin (20 and 40 mg) for effects on plasma concentrations of lipoproteins and apolipoprotein A-I over 12 weeks in 842 patients with elevated low-density lipoprotein cholesterol. The 2 agents reduced low-density lipoprotein cholesterol and triglycerides to a comparable degree, but simvastatin raised high-density lipoprotein cholesterol and apolipoprotein A-I more than atorvastatin, suggesting differences in metabolic effects of the 2 agents on plasma lipids and lipoproteins.
Anticholesteremic Agents↗
Mutant transcripts of the LDL receptor gene: mRNA structure and quantity.
mRNA of the low-density lipoprotein receptor (LDLR) gene from 22 heterozygous familial hypercholesterolemic subjects possessing different mutations in this gene was analyzed by Northern blot analysis and reverse transcription-polymerase chain reaction (RT-PCR) in order to detect abnormally spliced transcripts. These analyses revealed abnormally spliced transcripts for the two splice-site mutations 1359-1G-->A and 1705 + 1G-->T. The abnormally spliced transcript for mutation 1359-1G-->A was caused by activation of a cryptic acceptor splice site in exon 10. As a result, seven nucleotides of exon 10 were deleted. For mutation 1705 + 1G-->T, two mutant transcripts were observed. In the first transcript, exon 10 was spliced to exon 13, and in the second transcript intron 11 was retained. The relative amount of mutant transcripts from 14 of the 22 subjects was determined by use of an RT-PCR-based method. Quantitation of the relative amounts of mutant transcripts for five missense mutations resulted in a mean value (+/-SD) of 52.8% (+/-4.55). In comparison, quantitation of the relative amounts of mutant transcripts for five nonsense mutations resulted in a mean value of 31.8% (+/-6.91). This value was significantly lower than the value of 54.2% (+/-2.38) obtained for nine healthy subjects (P < 0.0001). The relative amount of mutant transcripts for the 1705 + 1G-->T mutation was 36%. Thus, transcripts from alleles containing premature stop codons are present in reduced amounts, whereas transcripts from alleles containing missense mutations are present in normal amounts. These findings underscore the importance of determining how mutations affect mRNA structure and quantity in order to understand how mutations cause disease.
Alleles↗
Under-reporting of dietary intake by smoking and non-smoking subjects counselled for hypercholesterolaemia.
OBJECTIVES: We asked whether under-reporting of energy and cigarette smoking were associated with choice of foods and dietary composition amongst subjects with hypercholesterolaemia who had received dietary instruction to lower serum cholesterol. DESIGN, SETTING AND SUBJECTS: Dietary intake was assessed with a 4-day weighed food record in 205 women and 141 men, aged 20-73 years, being treated at a lipid clinic (tertiary referral centre). Under-reporting was assessed by calculating the ratio of energy intake (EI) to estimated basal metabolic rate (BMR). RESULTS: The median EI/BMR was 1.1 for both men and women. EI/BMR did not differ according to smoking status, but correlated negatively with body mass index (Spearman's rho = -0.32, P = 0.0001). EI/BMR was inversely associated with energy-adjusted intakes of potatoes, vegetables, fish and low-fat meats, and positively associated with intakes of nuts, potato crisps, chocolate, sour and ice cream, oils, fatty meat spreads, cakes and biscuits, and with alcohol. Thus, low EI/BMR was associated with increased energy-adjusted intakes of protein, thiamine, riboflavin, niacin, iron and cholesterol and with decreased intakes of sugar, poly- and monounsaturated fats and vitamin E (all P < 0.05). Cigarette smokers had a higher energy percentage (E%) from fat than non-smokers (29 +/- 6 vs. 26 +/- 6), a lower E% from carbohydrates (50 +/- 7 vs. 54 +/- 7) and a lower intake of vitamin C (11 +/- 7 vs. 16 +/- 9 mg MJ-1; all P = 0.0001), reflecting an increased intake of fatty meats and a decreased intake of skimmed cheese, fruit, rice and pasta, and cakes and biscuits (all P < 0.05). CONCLUSION: Weighed dietary records reflected a 'healthier' intake of fat, protein, sugar, alcohol and some micronutrients amongst under-reporters, suggesting that self-reported dietary intakes are biased in patients with hypercholesterolaemia. Lack of responsiveness to the diet should not be assumed when dietary data are based on self-report. Smokers report a higher intake of fat and lower intake of vitamin C than non-smokers, even after dietary counsel, and may require more intensive interventions to optimize the diet.
Adult↗
Efficacy and safety of cerivastatin, 0.2 mg and 0.4 mg, in patients with primary hypercholesterolaemia: a multinational, randomised, double-blind study. Cerivastatin Study Group.
Elevated serum cholesterol level is a key risk factor for cardiovascular morbidity and mortality. Cerivastatin is a highly effective lipid-lowering agent currently licensed at doses of 0.1, 0.2, 0.3 and 0.4 mg. This was a multicentre, randomised, double-blind, parallel-group study comparing the efficacy and safety of cerivastatin 0.4 mg/day with that of cerivastatin 0.2 mg/day in patients with primary hypercholesterolaemia. There was a six-week placebo run-in phase followed by a 24-week active treatment phase. A total of 494 patients were randomised to receive cerivastatin 0.4 mg (n = 332) or 0.2 mg (n = 162). Per-protocol (PP) analysis revealed that mean low-density lipoprotein cholesterol (LDL-C) level decreased by 38.4 +/- 0.7% from baseline in the 0.4 mg group, compared with a decrease of 31.5 +/- 0.9% in the 0.2 mg group (p < 0.0001). There was a significant gender difference in the 0.4 mg group: LDL-C decreased by 44.4 +/- 8.9% in women, compared with a decrease of 37.0 +/- 0.9% in men (p < 0.046). In the PP group as a whole, total cholesterol decreased by 26.0 +/- 0.5% from baseline in the 0.4 mg group, compared with a decrease of 21.6 +/- 0.7% in the 0.2 mg group (p < 0.0001). Both doses were well tolerated; only eight (2.4%) patients in the 0.4 mg group and five (3.1%) patients in the 0.2 mg group withdrew owing to adverse events. Cerivastatin 0.2 mg/day and 0.4 mg/day was found to lower low-density lipoprotein cholesterol and total cholesterol levels in a dose-dependent manner, with both doses exhibiting a good safety profile.
Adult↗
An update on familial hypercholesterolaemia.
A report of a World Health Organization consultation on familial hypercholesterolaemia (FH) was recently presented in Geneva. The report provides an update on several aspects of FH such as the molecular basis, DNA diagnosis, clinical criteria for the diagnosis, treatment of FH adults and children, the role of diet, psychosocial aspects of FH, contacting and helping relatives with FH and gives suggestions for government cooperation. The report is reviewed here.
Adult↗
Phenotypic consequences of a deletion of exons 2 and 3 of the LDL receptor gene.
Screening for structural alterations of the low density lipoprotein (LDL) receptor gene by Southern blot analysis revealed an abnormal band pattern in one subject with a clinical diagnosis of homozygous familial hypercholesterolemia (FH). The molecular defect was further characterized by polymerase chain reaction and cDNA sequencing. These analyses identified a 4.8 kb in-frame deletion of exons 2 and 3, where exon 1 was spliced to exon 4. This deletion is expected to produce a receptor that has lost the two first cysteine-rich repeats of the ligand-binding domain. Previously published data of in vitro site-directed mutagenesis has shown that binding of LDL to such a receptor is reduced to 70% of normal. A mild phenotype in our FH homozygote is consistent with that observation. In contrast, heterozygotes carrying this deletion have a relatively more severe phenotype that is comparable to that of heterozygotes carrying a null-allele. A severe phenotype was also found in a compound heterozygote carrying this deletion. Possible mechanisms for this phenotypic variability are discussed.-Rødningen, O. K., S. Tonstad, J. D. Medh, D. A. Chappell, L. Ose, and T. P. Leren. Phenotypic consequences of a deletion of exons 2 and 3 of the LDL receptor gene.
Base Sequence↗
Clinical efficacy and safety of cerivastatin: summary of pivotal phase IIb/III studies.
Cerivastatin is a new, third-generation 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor ("statin"), which is administered to hypercholesterolemic patients at doses equivalent to 1-3% of the doses of other statins. This report reviews the pivotal Phase IIb/III clinical trials in which the efficacy and safety of cerivastatin was compared with placebo and active comparator statins (lovastatin, simvastatin, and pravastatin) after both short- and long-term administration. Overall, the studies showed that at doses of 0.025-0.4 mg/day, cerivastatin produced dose-dependent reductions in low-density lipoprotein (LDL) cholesterol and total cholesterol, which were significantly greater than placebo. The greatest reductions were achieved with 0.4 mg/day cerivastatin. On this dose, >40% of patients achieved reductions in LDL cholesterol >40% and in a further 9% of patients, LDL cholesterol was decreased by >50%. At higher doses, cerivastatin also demonstrated potent triglyceride-lowering effects in a subgroup of patients with raised plasma triglycerides. Reductions in atherogenic lipids and lipoproteins were accompanied by significant increases in high-density lipoprotein (HDL) cholesterol, apolipoprotein A-I, and antiatherogenic lipoprotein A-I. Long-term administration of cerivastatin for periods of up to 2 years was associated with persistent reductions in LDL cholesterol, total cholesterol, triglycerides, and apolipoprotein B as well as increases in HDL cholesterol similar to those observed after initial administration. Long-term cerivastatin treatment was also well tolerated. There was no significant difference between the incidence of adverse effects with cerivastatin and comparator statins or between cerivastatin and other statins with respect to clinically significant increases in either hepatic enzymes or creatine phosphokinase. In conclusion, these studies indicate that cerivastatin is a safe and effective long-term treatment for patients with primary hypercholesterolemia and also suggest that higher doses should be investigated.
Adolescent↗
[Attitude to genetic screening for familial hypercholesterolemia].
Familial hypercholesterolemia causes premature cardiovascular disease. Genetic screening of patients' relatives who have already been diagnosed has proved to be more efficient than screening in a general population. Privacy laws in Norway forbid physicians to directly contact persons with genetic disorders who are not their own patients. We examined attitudes towards this type of screening in a representative sample of the Norwegian population and a group of patients with familial hypercholesterolaemia. In both groups the majority showed a positive attitude towards physicians contacting relatives directly to detect individuals with familial hypercholesterolaemia. In both groups the majority wanted to know whether, based on the diagnosis of relatives, they might also be affected. Both groups wanted this information regardless of the risk of their being affected. We conclude that the privacy laws should be amended to conform with the attitudes of the population and the patients, thus enabling physicians to contact relatives directly.
Attitude to Health↗
[Referrals to the Lipid clinic--"appropriate" patients with inadequate anamnesis].
We examined 199 consecutive referrals to the Lipid Clinic at the National hospital in 1995 in order to compare referral- and chart data on familial hyperlipidaemia, familial cardiovascular disease, diagnosis, and lifestyle. 78% of referrals were from general practitioners. Most of the referrals included information on familial hyperlipidaemia and cardiovascular disease and on diet, but did not specify a lipid diagnosis. Less than half of the referrals included information on smoking habits (which was almost always specified in the chart). Up to 80% did not include information on alcohol, body mass index and physical activity, which was also often missing in the chart. We conclude that the referring doctors, and to some extent the clinic physicians, identified patients with a familial risk of cardiovascular disease, but they did not appear to characterise important lifestyle habits related to cardiovascular risk.
Adult↗
Effects of a 9.6-kb deletion of the LDL receptor gene (FH Helsinki) on structure and levels of mRNA.
FH Helsinki is a deletion of the low-density lipoprotein receptor (LDLR) gene that deletes 9.6 kb from intron 15 to exon 18. Screening for mutant transcripts by Northern blot analysis from a patient heterozygous for FH Helsinki revealed two mutant transcripts. One was a transcript where the proximal part of intron 15 was retained in mRNA. The second was a transcript where exon 15 was spliced to nucleotide 4186 of exon 18. Thus, this transcript was generated using the normal donor splice site in intron 15, and a cryptic AG acceptor splice site in exon 18. Translation of the two mutant transcripts is predicted to give nonfunctional proteins, as both the membrane-spanning domain and the cytoplasmic domain of the receptor are deleted. Scanning of the autoradiograms showed that the amounts of each of the two mutant transcripts were approximately 10 times higher than that of the normal transcript in our heterozygous patient. The finding of higher levels of mutant transcripts was confirmed by an allele-specific transcript quantitation method, in which the amount of the two mutant transcripts together was approximately 5 times higher than the amount of the normal transcript. Deletion of destabilizing elements (AU-rich elements) by FH Helsinki are proposed to cause the increased levels of mutant transcripts.
Base Sequence↗