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66 THE MOLECULAR BASIS OF AUTOSOMAL DOMINANT HYPERCHOLESTEROLEMIA: ASSESSMENT IN A LARGE COHORT OF HYPERCHOLESTEROLEMIC CHILDREN
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Atherosclerosis Supplements 12, no. 1 (2011) 13–184
65 MILDER PHENOTYPE OF RELATIVES OF INDEX PATIENTS CAN MISDIAGNOSE FAMILIAL HYPERCHOLESTEROLEMIA A.M. Medeiros1,2 , A.C. Alves1,2 , M. Bourbon1,2 , on behalf of the Investigators of the Portuguese FH Study. 1 Instituto Nacional de Saude ´ Dr. Ricardo Jorge, 2 BioFIG − Center for Biodiversity, Functional & Integrative Genomics, Lisbon, Portugal Familial Hypercholesterolemia (FH) is a genetic disorder characterized by high levels of LDLc in plasma, accelerated atherosclerosis and increased risk of premature coronary heart disease (pCHD). FH results from mutations in three genes involved in lipid metabolism: LDLR, APOB, PCSK9. It is known that FH patients’ phenotype is heterogeneous varying with different conditions, as gene and type of mutation. The present study pretends to characterize the biochemical profile of FH patients genetically identified in Portugal. The Portuguese FH Study identified 420 patients: 182 index (60 children, 122 adults) and 238 relatives (56 children, 182 adults) with a genetic defect. Biochemical parameters (total cholesterol (TC), LDLc, HDLc, triglycerides, ApoB, ApoAI) were analyzed with SPSS software using ANOVA tests. TC and LDLc levels are statistically higher in index patients than in relatives identified in cascade screening: index children, TC=315.96±61.51 mg/dl and LDLc=239.61±60.43 mg/dl vs TC=277.52±66.40 mg/dl and LDLc=209.05±53.44 mg/dl for relatives children (p = 0.002, p = 0.014); index adults TC = 369.56±78.94 mg/dl and LDLc = 287.72±78.93 mg/dl vs TC=332.93±75.54 mg/dl and LDLc=246.26 ±71.79 mg/dl for relatives adults (p < 0.001, p = 0.001). Although CT and LDLc mean values are above FH criteria a considered number of relatives have both TC and LDLc bellow these values (16%). Only 40% of relatives adults genetically identified are in treatment and 13% have pCHD vs 79% of index adults in treatment and 25% have pCHD.Genetic diagnosis of FH in Portugal allows early identification of FH patients, in particular relatives with mild phenotype that would not be identified by clinical criteria alone, allowing early implementation of therapeutic measures that will reduce their cardiovascular risk. 66 THE MOLECULAR BASIS OF AUTOSOMAL DOMINANT HYPERCHOLESTEROLEMIA: ASSESSMENT IN A LARGE COHORT OF HYPERCHOLESTEROLEMIC CHILDREN A. van der Graaf, H.J. Avis, D.M. Kusters, M.N. Vissers, B.A. Hutten, J.C. Defesche, R. Huijgen, S.W. Fouchier, F.A. Wijburg, J.J. Kastelein, A. Wiegman. AMC, Amsterdam, The Netherlands Background: Autosomal dominant hypercholesterolemia (ADH) is characterized by elevated low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease (CVD). Mutations in the genes encoding for the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin 9 (PCSK9) underlie ADH. Nevertheless, a proportion of individuals that exhibit the ADH phenotype do not carry mutations in any of these three genes. Estimates about the percentage of such cases amongst the ADH phenotype vary widely. We therefore investigated a large pediatric population with an unequivocal ADH phenotype to assess the molecular basis of hereditary hypercholesterolemia and define the percentage of individuals with unexplained dyslipidemia. Methods and Results: We enrolled individuals with LDL-C levels above the 95th percentile for age and gender and an autosomal dominant inheritance pattern of hypercholesterolemia from a large referred pediatric cohort of 1430 children. We excluded children with thyroid dysfunction, nephrotic syndrome, autoimmune disease, liver disease, primary biliary cirrhosis, obesity (BMI >75th percentile for age and gender), as well as children referred via a cascade screening program and those from families with a known molecular diagnosis. Of the 269 children that remained after applying the exclusion criteria, 255 (95%) carried a functional mutation (LDLR 95%; APOB 5%). Conclusion: In the vast majority of children with an ADH phenotype, a causative mutation can be identified, strongly suggesting that most of the large effect genes underlying ADH are known to date. 67 LOW LIPOPROTEIN(A) CONCENTRATION IS ASSOCIATED WITH SHORTER SURVIVAL: A POPULATION-BASED COHORT STUDY (THE JMS COHORT STUDY) M. Sawabe1 , N. Tanaka2 , M.N. Mieno3 , S. Ishikawa4 , K. Kayaba5 , K. Nakahara6 , S. Matsushita6 , The JMS Cohort Study Group. 1 Bioresource Center for Geriatric Research, Tokyo Metropolitan Geriatric Hospital, Itabashi, Japan, 2 Department of Biostatistics, Harvard School of Public Health, Boston, MA, USA, 3 Department of Medical Informatics, 4 Center for Community Medicine, Jichi Medical University, Shimotsuke, 5 Saitama Prefectural University, Koshigaya, 6 Department of Internal Medicine, Tokyo Metropolitan Geriatric Hospital, Itabashi, Japan Background: Experimental studies support the anti-neoplastic effect of apo(a), but several clinical studies have reported contradictory results. To determine whether a low lipoprotein(a) [Lp(a)] concentration may promote carcinogenesis,
Poster presentations
data from the Jichi Medical School cohort study, a multi-center population-based cohort study conducted in Japan, was analyzed. Methods: The subjects were 10,692 study participants (4,122 men and 6,570 women). The average age at registration was 55.2 years, and the median observation period was 4,559 days. A total of 899 participants died during the observation period. Results: The estimated hazard ratio was high for both low and very high Lp(a) levels. We defined three Lp(a) groups: low Lp(a) group [Lp(a) < 80 mg/L], intermediate Lp(a) group [80 Lp(a) < 550], and very high Lp(a) group [Lp(a) 550]. A Kaplan-Meier plot showed higher cumulative death rates for the low Lp(a) group than for the intermediate Lp(a) group for all-cause, cancer and miscellaneous-cause deaths (p < 0.001, p = 0.03, and p = 0.03, respectively). A Cox proportional hazards analysis showed that a low Lp(a) level was a significant risk for all-cause, cancer and miscellaneous-cause deaths (p < 0.001, p = 0.006, and p = 0.004, respectively). The hazard ratio (1.43) of a low Lp(a) level for all-cause deaths almost reached that (1.52) of a male sex. Conclusions: These results support the anti-neoplastic effect of Lp(a). Thus, Lp(a)-lowering drugs presently under development might promote cancer or allcause deaths. This novel finding also supports the epidemiological significance of a low Lp(a) concentration. 68 THE FUNCTION OF APOA5 IN THE METABOLISM OF TRIGLYCERIDERICH LIPOPROTEINS (TRL) PARTIALLY DEPENDS ON LRP1 1 K. Brugelmann ¨ , A. Bartelt1 , J. Heeren1 , M. Merkel2 . 1 IBMII: Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 2 Department of Internal Medicine, Asklepios Clinic St. George, Hamburg, Germany
Objective: Apolipoprotein A5 is a strong modulator in the metabolism of TRL. It was shown that apoA5 activates lipoprotein lipase and thereby accelerates plasma TG hydrolysis. In vitro studies suggest that apoA5 may also mediate lipoprotein uptake by members of the LDL receptor (LDLR) family. This study investigates interactions of apoA5 with lipoprotein receptors in vivo and in primary hepatocytes in vitro. Methods: The TG-lowering effect of the human apoA5 transgene (A5tr) was investigated in mice with LDLR deficiency (LDLR−/− ), in mice lacking hepatic LRP1 (hLRP1−/− ) and respective littermate wildtype controls (hLRP1+/+ ) as well as in LRP1-LDLR-knockout mice (LDLR−/− -hLRP1−/− ) and hLRP1 controls (LDLR−/− -hLRP1+/+ ). The secretion of apoA5 protein in plasma and in cell supernatants of primary hepatocytes was measured by Elisa. Results: In LDLR−/− mice apoA5 decreased TRL-TG by 46%. In hLRP1+/+ -A5tr mice TG levels are 30% decreased compared to hLRP1+/+ -Wt. In contrast, in hLRP1−/− A5tr mice, the decreasing effect of apoA5 is abolished. In LDLR−/− hLRP1+/+ -A5Tr, TG levels are 25% decreased compared to LDLR−/− -hLRP1−/− A5tr mice. In mice lacking hLRP1 as well as in LDLR−/− -hLRP1−/− the A5tr plasma concentration was 36% increased in contrast to hLRP1+/+ and 45% in contrast to LDLR−/− -hLRP1−/− -A5tr mice. To further elucidate a possible interaction of LRP1 and apoA5 experiments with primary hepatocytes are in progress. Preliminary data showed an increase of apoA5 protein in cell supernatants in the absence of LRP1. Conclusion: These data suggest that LRP1 is involved in the secretion of apoA5 and/or in the trapping of TRL remnants into the liver. 69 HOMOZYGOUS FAMILIAL HYPERCHOLESTEROLEMIA IN NORWAY, SWEDEN, DENMARK AND FINLAND − SUBSTANTIAL VARIATION IN FREQUENCY OF THE DIAGNOSIS 3 A. Græsdal1 , M.P. Bogsrud2 , Y. Stalstrøm ˚ , K. Retterstøl2 , G. Langslet2 , L. Ose2 . 1 Vestfold Indremedisinske Senter, Sandefjord, 2 Lipid Clinic, Oslo University Hospital, Rikshospitalet, Oslo, 3 Gambro, Tønsberg, Norway
Background and Aims: Homozygous familial hypercholesterolemia (HFH) is caused by homozygosity or compound heterozygosity in genes encoding the low density lipoprotein (LDL) receptor. The prevalence is roughly estimated to be 1 per million among European Caucasians. Due to extreme cholesterol values myocardial infarction can occur in early childhood and most of the patients will die before the age of 30 if not treated with cholesterol lowering medications and LDL-apheresis. The aim of this study is to compare the frequency of the diagnosis and relevant treatment in the Nordic countries. Methods: In Norway all patients with HFH are registered at the Lipid Clinic in Oslo. In the other Nordic countries no central clinic exists, but we have contacted the hospitals to obtain an overview of the number of HFH patients. Results: In Norway 8 of 4.8 million inhabitans have the diagnosis − one has underwent liver transplantation, the remaining 7 are treated with LDL-apheresis. In Finland none of 5.3 million inhabitans is known to be diagnosed. In Sweden 8 of 9.3 million inhabitans have been diagnosed and are treated with apheresis. In Denmark 2 of 5.5 million inhabitans are diagnosed, one is in apheresis treatment, and one is planned for apheresis treatment. Conclusion: The great variation in frequency of patients with HFH between the Nordic countries in this study, is likely to represent an underdiagnosis of this severe condition. We propose that all patients wtith HFH are registered nationally and that the effect of the apheresis treatment is recorded.
Atherosclerosis Supplements 12, no. 1 (2011) 13–184
65 MILDER PHENOTYPE OF RELATIVES OF INDEX PATIENTS CAN MISDIAGNOSE FAMILIAL HYPERCHOLESTEROLEMIA A.M. Medeiros1,2 , A.C. Alves1,2 , M. Bourbon1,2 , on behalf of the Investigators of the Portuguese FH Study. 1 Instituto Nacional de Saude ´ Dr. Ricardo Jorge, 2 BioFIG − Center for Biodiversity, Functional & Integrative Genomics, Lisbon, Portugal Familial Hypercholesterolemia (FH) is a genetic disorder characterized by high levels of LDLc in plasma, accelerated atherosclerosis and increased risk of premature coronary heart disease (pCHD). FH results from mutations in three genes involved in lipid metabolism: LDLR, APOB, PCSK9. It is known that FH patients’ phenotype is heterogeneous varying with different conditions, as gene and type of mutation. The present study pretends to characterize the biochemical profile of FH patients genetically identified in Portugal. The Portuguese FH Study identified 420 patients: 182 index (60 children, 122 adults) and 238 relatives (56 children, 182 adults) with a genetic defect. Biochemical parameters (total cholesterol (TC), LDLc, HDLc, triglycerides, ApoB, ApoAI) were analyzed with SPSS software using ANOVA tests. TC and LDLc levels are statistically higher in index patients than in relatives identified in cascade screening: index children, TC=315.96±61.51 mg/dl and LDLc=239.61±60.43 mg/dl vs TC=277.52±66.40 mg/dl and LDLc=209.05±53.44 mg/dl for relatives children (p = 0.002, p = 0.014); index adults TC = 369.56±78.94 mg/dl and LDLc = 287.72±78.93 mg/dl vs TC=332.93±75.54 mg/dl and LDLc=246.26 ±71.79 mg/dl for relatives adults (p < 0.001, p = 0.001). Although CT and LDLc mean values are above FH criteria a considered number of relatives have both TC and LDLc bellow these values (16%). Only 40% of relatives adults genetically identified are in treatment and 13% have pCHD vs 79% of index adults in treatment and 25% have pCHD.Genetic diagnosis of FH in Portugal allows early identification of FH patients, in particular relatives with mild phenotype that would not be identified by clinical criteria alone, allowing early implementation of therapeutic measures that will reduce their cardiovascular risk. 66 THE MOLECULAR BASIS OF AUTOSOMAL DOMINANT HYPERCHOLESTEROLEMIA: ASSESSMENT IN A LARGE COHORT OF HYPERCHOLESTEROLEMIC CHILDREN A. van der Graaf, H.J. Avis, D.M. Kusters, M.N. Vissers, B.A. Hutten, J.C. Defesche, R. Huijgen, S.W. Fouchier, F.A. Wijburg, J.J. Kastelein, A. Wiegman. AMC, Amsterdam, The Netherlands Background: Autosomal dominant hypercholesterolemia (ADH) is characterized by elevated low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease (CVD). Mutations in the genes encoding for the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin 9 (PCSK9) underlie ADH. Nevertheless, a proportion of individuals that exhibit the ADH phenotype do not carry mutations in any of these three genes. Estimates about the percentage of such cases amongst the ADH phenotype vary widely. We therefore investigated a large pediatric population with an unequivocal ADH phenotype to assess the molecular basis of hereditary hypercholesterolemia and define the percentage of individuals with unexplained dyslipidemia. Methods and Results: We enrolled individuals with LDL-C levels above the 95th percentile for age and gender and an autosomal dominant inheritance pattern of hypercholesterolemia from a large referred pediatric cohort of 1430 children. We excluded children with thyroid dysfunction, nephrotic syndrome, autoimmune disease, liver disease, primary biliary cirrhosis, obesity (BMI >75th percentile for age and gender), as well as children referred via a cascade screening program and those from families with a known molecular diagnosis. Of the 269 children that remained after applying the exclusion criteria, 255 (95%) carried a functional mutation (LDLR 95%; APOB 5%). Conclusion: In the vast majority of children with an ADH phenotype, a causative mutation can be identified, strongly suggesting that most of the large effect genes underlying ADH are known to date. 67 LOW LIPOPROTEIN(A) CONCENTRATION IS ASSOCIATED WITH SHORTER SURVIVAL: A POPULATION-BASED COHORT STUDY (THE JMS COHORT STUDY) M. Sawabe1 , N. Tanaka2 , M.N. Mieno3 , S. Ishikawa4 , K. Kayaba5 , K. Nakahara6 , S. Matsushita6 , The JMS Cohort Study Group. 1 Bioresource Center for Geriatric Research, Tokyo Metropolitan Geriatric Hospital, Itabashi, Japan, 2 Department of Biostatistics, Harvard School of Public Health, Boston, MA, USA, 3 Department of Medical Informatics, 4 Center for Community Medicine, Jichi Medical University, Shimotsuke, 5 Saitama Prefectural University, Koshigaya, 6 Department of Internal Medicine, Tokyo Metropolitan Geriatric Hospital, Itabashi, Japan Background: Experimental studies support the anti-neoplastic effect of apo(a), but several clinical studies have reported contradictory results. To determine whether a low lipoprotein(a) [Lp(a)] concentration may promote carcinogenesis,
Poster presentations
data from the Jichi Medical School cohort study, a multi-center population-based cohort study conducted in Japan, was analyzed. Methods: The subjects were 10,692 study participants (4,122 men and 6,570 women). The average age at registration was 55.2 years, and the median observation period was 4,559 days. A total of 899 participants died during the observation period. Results: The estimated hazard ratio was high for both low and very high Lp(a) levels. We defined three Lp(a) groups: low Lp(a) group [Lp(a) < 80 mg/L], intermediate Lp(a) group [80 Lp(a) < 550], and very high Lp(a) group [Lp(a) 550]. A Kaplan-Meier plot showed higher cumulative death rates for the low Lp(a) group than for the intermediate Lp(a) group for all-cause, cancer and miscellaneous-cause deaths (p < 0.001, p = 0.03, and p = 0.03, respectively). A Cox proportional hazards analysis showed that a low Lp(a) level was a significant risk for all-cause, cancer and miscellaneous-cause deaths (p < 0.001, p = 0.006, and p = 0.004, respectively). The hazard ratio (1.43) of a low Lp(a) level for all-cause deaths almost reached that (1.52) of a male sex. Conclusions: These results support the anti-neoplastic effect of Lp(a). Thus, Lp(a)-lowering drugs presently under development might promote cancer or allcause deaths. This novel finding also supports the epidemiological significance of a low Lp(a) concentration. 68 THE FUNCTION OF APOA5 IN THE METABOLISM OF TRIGLYCERIDERICH LIPOPROTEINS (TRL) PARTIALLY DEPENDS ON LRP1 1 K. Brugelmann ¨ , A. Bartelt1 , J. Heeren1 , M. Merkel2 . 1 IBMII: Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 2 Department of Internal Medicine, Asklepios Clinic St. George, Hamburg, Germany
Objective: Apolipoprotein A5 is a strong modulator in the metabolism of TRL. It was shown that apoA5 activates lipoprotein lipase and thereby accelerates plasma TG hydrolysis. In vitro studies suggest that apoA5 may also mediate lipoprotein uptake by members of the LDL receptor (LDLR) family. This study investigates interactions of apoA5 with lipoprotein receptors in vivo and in primary hepatocytes in vitro. Methods: The TG-lowering effect of the human apoA5 transgene (A5tr) was investigated in mice with LDLR deficiency (LDLR−/− ), in mice lacking hepatic LRP1 (hLRP1−/− ) and respective littermate wildtype controls (hLRP1+/+ ) as well as in LRP1-LDLR-knockout mice (LDLR−/− -hLRP1−/− ) and hLRP1 controls (LDLR−/− -hLRP1+/+ ). The secretion of apoA5 protein in plasma and in cell supernatants of primary hepatocytes was measured by Elisa. Results: In LDLR−/− mice apoA5 decreased TRL-TG by 46%. In hLRP1+/+ -A5tr mice TG levels are 30% decreased compared to hLRP1+/+ -Wt. In contrast, in hLRP1−/− A5tr mice, the decreasing effect of apoA5 is abolished. In LDLR−/− hLRP1+/+ -A5Tr, TG levels are 25% decreased compared to LDLR−/− -hLRP1−/− A5tr mice. In mice lacking hLRP1 as well as in LDLR−/− -hLRP1−/− the A5tr plasma concentration was 36% increased in contrast to hLRP1+/+ and 45% in contrast to LDLR−/− -hLRP1−/− -A5tr mice. To further elucidate a possible interaction of LRP1 and apoA5 experiments with primary hepatocytes are in progress. Preliminary data showed an increase of apoA5 protein in cell supernatants in the absence of LRP1. Conclusion: These data suggest that LRP1 is involved in the secretion of apoA5 and/or in the trapping of TRL remnants into the liver. 69 HOMOZYGOUS FAMILIAL HYPERCHOLESTEROLEMIA IN NORWAY, SWEDEN, DENMARK AND FINLAND − SUBSTANTIAL VARIATION IN FREQUENCY OF THE DIAGNOSIS 3 A. Græsdal1 , M.P. Bogsrud2 , Y. Stalstrøm ˚ , K. Retterstøl2 , G. Langslet2 , L. Ose2 . 1 Vestfold Indremedisinske Senter, Sandefjord, 2 Lipid Clinic, Oslo University Hospital, Rikshospitalet, Oslo, 3 Gambro, Tønsberg, Norway
Background and Aims: Homozygous familial hypercholesterolemia (HFH) is caused by homozygosity or compound heterozygosity in genes encoding the low density lipoprotein (LDL) receptor. The prevalence is roughly estimated to be 1 per million among European Caucasians. Due to extreme cholesterol values myocardial infarction can occur in early childhood and most of the patients will die before the age of 30 if not treated with cholesterol lowering medications and LDL-apheresis. The aim of this study is to compare the frequency of the diagnosis and relevant treatment in the Nordic countries. Methods: In Norway all patients with HFH are registered at the Lipid Clinic in Oslo. In the other Nordic countries no central clinic exists, but we have contacted the hospitals to obtain an overview of the number of HFH patients. Results: In Norway 8 of 4.8 million inhabitans have the diagnosis − one has underwent liver transplantation, the remaining 7 are treated with LDL-apheresis. In Finland none of 5.3 million inhabitans is known to be diagnosed. In Sweden 8 of 9.3 million inhabitans have been diagnosed and are treated with apheresis. In Denmark 2 of 5.5 million inhabitans are diagnosed, one is in apheresis treatment, and one is planned for apheresis treatment. Conclusion: The great variation in frequency of patients with HFH between the Nordic countries in this study, is likely to represent an underdiagnosis of this severe condition. We propose that all patients wtith HFH are registered nationally and that the effect of the apheresis treatment is recorded.