Gaps in the Care of Familial Hypercholesterolaemia in Australia: First Report From the National Registry.

BACKGROUND: Familial hypercholesterolaemia (FH) is under-diagnosed and under-treated worldwide, including Australia. National registries play a key role in identifying patients with FH, understanding gaps in care and advancing the science of FH to improve care for these patients. METHODS: The FH Australasia Network has established a national web-based registry to raise awareness of the condition, facilitate service planning and inform best practice and care services in Australia. We conducted a cross-sectional analysis of 1,528 FH adults enrolled in the registry from 28 lipid clinics. RESULTS: The mean age at enrolment was 53.4±15.1 years, 50.5% were male and 54.3% had undergone FH genetic testing, of which 61.8% had a pathogenic FH-causing gene variant. Only 14.0% of the cohort were family members identified through cascade testing. Coronary artery disease (CAD) was reported in 28.0% of patients (age of onset 49.0±10.5 years) and 64.9% had at least one modifiable cardiovascular risk factor. The mean untreated LDL-cholesterol was 7.4±2.5 mmol/L. 80.8% of patients were on lipid-lowering therapy with a mean treated LDL-cholesterol of 3.3±1.7 mmol/L. Among patients receiving lipid-lowering therapies, 25.6% achieved an LDL-cholesterol target of <2.5 mmol/L without CAD or <1.8 mmol/L with CAD. CONCLUSION: Patients in the national FH registry are detected later in life, have a high burden of CAD and risk factors, and do not achieve guideline-recommended LDL-cholesterol targets. Genetic and cascade testing are under-utilised. These deficiencies in care need to be addressed as a public health priority.

ω-3 Fatty Acid Ethyl Esters Diminish Postprandial Lipemia in Familial Hypercholesterolemia.

CONTEXT: Impaired postprandial chylomicron metabolism induces hypertriglyceridemia and may increase the risk of atherosclerotic cardiovascular disease. Omega-3 fatty acid ethyl ester (ω-3 FAEE) supplementation decreases plasma triglycerides. However, its effect on postprandial chylomicron metabolism in familial hypercholesterolemia (FH) has not yet been investigated. OBJECTIVE: We aimed to examine the effect of ω-3 FAEE supplementation on postprandial responses in plasma triglycerides, very-low-density lipoprotein (VLDL) apolipoprotein B (apoB)-100, and apoB-48 in FH patients receiving standard cholesterol-lowering treatment. DESIGN, SETTING, AND PATIENTS: We carried out an 8-week open-label, randomized, crossover intervention trial to test the effect of oral supplementation with 4 g/d ω-3 FAEE (46% eicosapentaenoic acid and 38% docosahexaenoic acid) on postprandial triglyceride, VLDL-apoB-100, and apoB-48 responses in FH patients after ingestion of an oral fat load. OUTCOMES MEASURES: Plasma total and incremental triglyceride, VLDL-apoB-100, and apoB-48 0- to 10-hour area under the curve (AUC). RESULTS: ω-3 FAEE supplementation significantly (P < .05 in all) reduced concentrations of fasting plasma triglyceride (-20%), apoB (-8%), VLDL-apoB-100 (-26%), and apoB-48 (-36%); as well as systolic blood pressure (-6%) and diastolic blood pressure (-6%). Postprandial triglyceride and VLDL-apoB-100 total AUCs (-19% and -26%, respectively; P < .01) and incremental AUCs (-18% and -35%, respectively; P < .05), as well as postprandial apoB-48 total AUC (-30%; P < .02) were significantly reduced by ω-3 FAEE supplementation. CONCLUSION: Supplementation with ω-3 FAEEs improves postprandial lipemia in FH patients receiving standard care; this may have implications for further reducing atherosclerotic cardiovascular disease in this high-risk patient group.

Lipoprotein metabolism in an apoB-80 familial hypobetalipoproteinemia heterozygote.

OBJECTIVE: Familial hypobetalipoproteinemia (FHBL) is characterized by mutations in APOB, the majority of these causing protein truncations, and low plasma levels of apolipoprotein (apo) B. The hypobetalipoproteinemia may be due to enhanced clearance and possibly reduced production of apoB-containing lipoproteins; the mechanism may depend on the length of the apoB truncation. We studied fasting lipoprotein metabolism in an FHBL subject heterozygous for a mutation causing a truncated apoB, apoB-80. DESIGN AND METHODS: Very low density lipoprotein (VLDL)-, intermediate density lipoprotein (IDL)-, and low density lipoprotein (LDL)-apoB kinetics were determined in the fasting state using stable isotope methods and compartmental modeling. RESULTS: Compared with lean normolipidemic controls the apoB-80 FHBL subject had an elevated VLDL-apoB fractional catabolic rate and lower LDL production. ApoB production rates and IDL- and LDL-apoB fractional catabolic rates were not different. CONCLUSION: FHBL subjects heterozygous for a mutation truncating apoB to 80% of full-length are able to produce VLDL-apoB normally, but have rapid clearance of these particles, resulting in low levels of circulating apoB.

Elevated lipoprotein(a), hypertension and renal insufficiency as predictors of coronary artery disease in patients with genetically confirmed heterozygous familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is characterized by elevated LDL-cholesterol and increased risk of premature coronary artery disease (CAD). Lipoprotein(a) [Lp(a)] increases CAD in FH, although the independence of this association relative to other CAD risk factors remains unclear. In this study, we examined the association between Lp(a) and other cardiovascular risk factors and prevalent CAD in patients with FH. METHODS: A cross-sectional study of 390 patients with genetically confirmed FH were studied. Clinical and biochemical parameters of FH patients with and without CAD were compared. RESULTS: FH patients with CAD were older and more often male and had a higher prevalence of hypertension, smoking, diabetes, obesity, reduced eGFR, and elevated plasma Lp(a) and pre-treatment LDL-cholesterol and triglyceride (or low HDL-cholesterol) than FH patients without CAD (P<0.05 for all). In univariate analyses, age, male gender, smoking, hypertension, reduced eGFR, diabetes, obesity, plasma creatinine, Lp(a) and pretreatment LDL-cholesterol, triglycerides and HDL-cholesterol levels were significant predictors of CAD in the FH patients (P<0.05 for all). Elevated LDL-cholesterol, raised Lp(a), hypertension and reduced eGFR remained significant independent predictors of CAD (P<0.05 for all) in FH after adjusting for other modifiable risk factors. CONCLUSIONS: Elevated Lp(a), hypertension and renal insufficiency are independent risk factors beyond elevated pretreatment LDL-cholesterol which predict CAD in patients with FH. In spite of the cross-sectional design of our study, we propose the need for identifying and managing these abnormalities to reduce excess CAD risk in FH patients. However, this proposal remains to be formally tested in a prospective study.

Lipoprotein Metabolism in APOB L343V Familial Hypobetalipoproteinemia.

CONTEXT: Familial hypobetalipoproteinemia (FHBL) is a codominant disorder of lipoprotein metabolism characterized by decreased plasma concentrations of low-density lipoprotein (LDL)-cholesterol and apolipoprotein B (apoB). OBJECTIVE: The objective was to examine the effect of heterozygous APOB L343V FHBL on postprandial triglyceride-rich lipoprotein (TRL) and fasting lipoprotein metabolism. METHODS: Plasma incremental area under the curve apoB-48 and apoB-48 kinetics were determined after ingestion of a standardized oral fat load using compartmental modeling. Very low-density lipoprotein (VLDL)-, intermediate-density lipoprotein (IDL)-, and LDL-apoB kinetics were determined in the fasting state using stable isotope methods and compartmental modeling. RESULTS: The postprandial incremental area under the curve (0-10 h) in FHBL subjects (n = 3) was lower for large TRL-triglyceride (-77%; P < .0001), small TRL-cholesterol (-83%; P < .001), small TRL-triglyceride (-88%; P < .001), and for plasma triglyceride (-70%; P < .01) and apoB (-63%; P < .0001) compared with controls. Compartmental analysis showed that apoB-48 production was lower (-91%; P < .05) compared with controls. VLDL-apoB concentrations in FHBL subjects (n = 2) were lower by more than 75% compared with healthy, normolipidemic control subjects (P < .01). The VLDL-apoB fractional catabolic rate (FCR) was more than 5-fold higher in the FHBL subjects (P = .07). ApoB production rates and IDL- and LDL-apoB FCRs were not different between FHBL subjects and controls. CONCLUSIONS: We conclude that when compared to controls, APOB L343V FHBL heterozygotes show lower TRL production with normal postprandial TRL particle clearance. In contrast, VLDL-apoB production was normal, whereas the FCR was higher in heterozygotes compared with lean control subjects. These mechanisms account for the marked hypolipidemic state observed in these FHBL subjects.

The potential role of an expert computer system to augment the opportunistic detection of individuals with familial hypercholesterolaemia from a community laboratory.

BACKGROUND: Familial hypercholesterolaemia (FH) is the most common monogenic cause of premature atherosclerotic cardiovascular disease (CVD). However, most individuals with FH remain undiagnosed. We sought to determine if an expert system (ES) at a community laboratory could identify information relevant for estimating an individual's likelihood of FH using the Dutch Lipid Clinic Network criteria (DLCNC). METHODS: An ES (RippleDown®) retrospectively analysed laboratory results and clinical details on the current and previous lipid requests from a community laboratory in Western Australia, over 12months. RESULTS: 84,823 individuals had ≥1 LDL-cholesterol request with data available on 84,083 (99.1%). Clinical details were provided on 71,282 (84.8%) individuals' current or previous requests. History relevant to the DLCNC was present in 883 (1.1%) individuals, with premature CVD and non-cardiac vascular disease present in 177 and 64 individuals, respectively. Statin therapy was reported in 5118 individuals; 112 individuals with a current LDL-cholesterol of <6.5mmol/L had a previous LDL-cholesterol of ≥6.5mmol/L. CONCLUSIONS: The ES was able to identify information that increased the likelihood of FH in 5471 cases. The ability to detect individuals with premature CVD and to classify them based on their highest LDL-cholesterol may augment FH detection, although further investigation is required to confirm this.

Folate pathway gene polymorphisms and risk of childhood brain tumors: results from an Australian case-control study.

BACKGROUND: Recent research suggests that maternal folic acid supplementation is associated with a reduced risk of childhood brain tumors (CBT); polymorphisms in folate pathway genes could modify this association or directly influence CBT risk. METHODS: Associations between risk of CBT and folate pathway polymorphisms were investigated in a population-based case-control study in Australia (2005-2010). Cases were recruited through all Australian pediatric oncology centers and controls by national random digit dialing. Data were available from 321 cases and 552 controls. Six polymorphisms were genotyped in children and parents (MTHFR 677C>T, MTHFR 1298A>C, MTRR 66A>G, MTR 2756A>G, MTR 5049C>A, and CBS 2199 T>C). Maternal folic acid use was ascertained via questionnaire. ORs were estimated using unconditional logistic regression. Case-parent trio analyses were also undertaken. RESULTS: There was weak evidence of a reduced risk of CBT for the MTRR 66GG genotype in the child or father: ORs 0.71 [95% confidence interval (CI), 0.48-1.07]; 0.54 (95% CI, 0.34-0.87), respectively. Maternal prepregnancy folic acid supplementation showed a stronger negative association with CBT risk where the child, mother, or father had the MTRR 66GG genotype (Pinteraction = 0.07, 0.10, and 0.18, respectively). CONCLUSIONS: Evidence for an association between folate pathway genotypes and CBT is limited in this study. There was possible protection by the MTRR 66GG genotype, particularly when combined with maternal prepregnancy folic acid supplementation; these results are novel and require replication. IMPACT: The possible interaction between folic acid supplementation and MTRR 66A>G, if confirmed, would strengthen evidence for prepregnancy folate protection against CBT.

Paternal dietary folate, B6 and B12 intake, and the risk of childhood brain tumors.

It is biologically plausible that a paternal preconception diet low in nutrients related to DNA integrity could affect sperm DNA and subsequently risk of cancer in the offspring. The aim of this analysis was to investigate whether paternal preconception dietary folate, B6, or B12 intake was associated with the risk of childhood brain tumors (CBT) in an Australian case-control study. Cases <15 years of age were recruited from 10 Australian pediatric oncology centers between 2005 and 2010, and controls from random-digit dialing, frequency-matched to cases on age, sex, and state of residence. Paternal dietary information was obtained by food-frequency questionnaires. Nutrient values were energy adjusted and divided into tertiles for analysis by unconditional logistic regression. In fathers with relevant data (237 cases and 629 controls), no association with dietary folate and B6 and risk of CBT was seen; high B12 intake was associated with an increased risk of CBT (odds ratio highest vs. lowest tertile: 1.74, 95% confidence interval: 1.14, 2.66) without an increasing trend. These results do not support the hypothesis that paternal dietary folate intake influences the risk of CBT. The increased OR observed between dietary B12 intake and risk of CBT is without any certain explanation.

Effectiveness of genetic cascade screening for familial hypercholesterolaemia using a centrally co-ordinated clinical service: an Australian experience.

BACKGROUND: Familial hypercholesterolaemia (FH) is a co-dominantly inherited disorder of low-density lipoprotein (LDL) catabolism, causing elevated LDL-cholesterol and premature coronary artery disease (CAD). Several guidelines recommend genetic cascade screening relatives of probands (index cases) with genetically proven FH, but experience in a clinical service setting is limited. METHODS: Relatives from 100 index cases with genetically confirmed FH underwent genetic and lipid testing via a centralised screening program in Western Australia. The program's effectiveness was evaluated as the number of newly diagnosed relatives with FH per index case and the proportional reduction in LDL-cholesterol after treatment. RESULTS: Of 366 relatives tested for FH, 188 (51.4%) were found to have a pathogenic mutation. On average, 2 cases were detected per index case. Affected relatives were younger and less likely to have physical stigmata of FH and premature CAD than index cases (p < 0.001). Of the new cases, 12.8% had hypertension, 2.7% had diabetes and 16.0% were smokers; 48.4% were already on statin therapy and these were older (p < 0.001) and had more vascular risk factors and CAD (p < 0.01) than those not on therapy. Significant reductions in LDL-cholesterol (-24.3%, p < 0.001) were achieved overall, with previously untreated new cases of FH attaining a maximal average reduction of 42.5% in LDL-cholesterol after drug therapy. Over 90% of subjects were satisfied with screening and care. CONCLUSION: Genetic cascade screening co-ordinated by a centralised service is an effective and acceptable strategy for detecting FH in an Australian setting. A significant proportion of new cases exhibit other CAD risk factors and are already on statins, but have not received a prior diagnosis of FH.

Folate pathway gene polymorphisms, maternal folic acid use, and risk of childhood acute lymphoblastic leukemia.

BACKGROUND: Several studies suggest that maternal folic acid supplementation before or during pregnancy protects against childhood acute lymphoblastic leukemia (ALL). We investigated associations between ALL risk and folate pathway gene polymorphisms, and their modification by maternal folic acid supplements, in a population-based case-control study (2003-2007). METHODS: All Australian pediatric oncology centers provided cases; controls were recruited by national random digit dialing. Data from 392 cases and 535 controls were included. Seven folate pathway gene polymorphisms (MTHFR 677C>T, MTHFR 1298A>C, MTRR 66A>G, MTR 2756 A>G, MTR 5049 C>A, CBS 844 Ins68, and CBS 2199 T>C) were genotyped in children and their parents. Information on prepregnancy maternal folic acid supplement use was collected. ORs were estimated with unconditional logistic regression adjusted for frequency-matched variables and potential confounders. Case-parent trios were also analyzed. RESULTS: There was some evidence of a reduced risk of ALL among children who had, or whose father had, the MTRR 66GG genotype: ORs 0.60 [95% confidence interval (CI) 0.39-0.91] and 0.64 (95% CI, 0.40-1.03), respectively. The ORs for paternal MTHFR 677CT and TT genotypes were 1.41 (95% CI, 1.02-1.93) and 1.81 (95% CI, 1.06-3.07). ORs varied little by maternal folic acid supplementation. CONCLUSIONS: Some folate pathway gene polymorphisms in the child or a parent may influence ALL risk. While biologically plausible, underlying mechanisms for these associations need further elucidation. IMPACT: Folate pathway polymorphisms may be related to risk of childhood ALL, but larger studies are needed for conclusive results.

Novel missense MTTP gene mutations causing abetalipoproteinemia.

OBJECTIVE: The microsomal triglyceride transfer protein (MTTP) plays a critical role in the formation of hepatic very low density lipoprotein. Abetalipoproteinemia (ABL) is a rare, naturally occurring extreme form of MTTP inhibition, which is characterized by the virtual absence of apolipoprotein (apo) B-containing lipoproteins in blood. The goal of this study was to examine the effect that four novel MTTP missense mutations had on protein interactions, expression and lipid-transfer activity, and to determine which mutations were responsible for the ABL phenotype observed in two patients. APPROACH AND RESULTS: In two patients with ABL, we identified in MTTP a novel frameshift mutation (K35Ffs*37), and four novel missense mutations, namely, G264R, Y528H, R540C, and N649S. When transiently expressed in COS-7 cells, all missense MTTP mutations interacted with apoB17, apoB48, and protein disulfide isomerase. Mutations Y528H and R540C, however, displayed negligible levels of MTTP activity and N649S displayed a partial reduction relative to the wild-type MTTP. In contrast, G264R retained full lipid-transfer activity. CONCLUSIONS: These studies indicate that missense mutations Y528H, R540C, and N649S appear to cause ABL by reducing MTTP activity rather than by reducing binding of MTTP with protein disulfide isomerase or apoB. The region of MTTP containing amino acids 528 and 540 constitutes a critical domain for its lipid-transfer activity.

Cascade screening based on genetic testing is cost-effective: evidence for the implementation of models of care for familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) imposes significant burden of premature coronary heart disease (CHD). OBJECTIVE: This study aimed to determine the cost-effectiveness of FH detection based on genetic testing, supplemented with the measurement of plasma low-density lipoprotein cholesterol concentration, and treatment with statins. METHODS: A Markov model with a 10-year time horizon was constructed to simulate the onset of first-ever CHD and death in close relatives of probands with genetically confirmed FH. The model comprised of 3 health states: "alive without CHD," "alive with CHD," and "dead." Decision-analysis compared the clinical consequences and costs of cascade-screening vs no-screening from an Australian health care perspective. The annual risk of CHD and benefits of treatment was estimated from a cohort study. The underlying prevalence of FH, sensitivity, specificity, cost of screening, treatment, and clinic follow-up visits were derived from a cascade screening service for FH in Western Australia. An annual discount rate of 5% was applied to costs and benefits. RESULTS: The model estimated that screening for FH would reduce the 10-year incidence of CHD from 50.0% to 25.0% among people with FH. Of every 100 people screened, there was an overall gain of 24.95 life-years and 29.07 quality-adjusted life years (discounted). The incremental cost-effectiveness ratio was in Australian dollars, $4155 per years of life saved and $3565 per quality-adjusted life years gained. CONCLUSION: This analysis within an Australian context, demonstrates that cascade screening for FH, using genetic testing supplemented with the measurement of plasma low-density lipoprotein cholesterol concentrations and treatment with statins, is a cost-effective means of preventing CHD in families at risk of FH.

Grey matter changes associated with deficit awareness in mild cognitive impairment: a voxel-based morphometry study.

Reduced awareness of cognitive deficits in mild cognitive impairment (MCI) is associated with poorer outcomes although little is known about the anatomical correlates of this. We examined the association of insight and grey matter volume using a voxel-based morphometry approach in 65 volunteers with MCI and 55 healthy age-matched controls. Participants with MCI had multiple areas of subtle grey matter volume loss compared with controls, although these did not survive correction for multiple comparisons. These were predominantly in the temporal and anterior portions of the brain. Individuals with MCI did not differ from each other on a number of demographic and cognitive variables according to level of insight. Reduced awareness of cognitive deficits was associated with few differences in grey matter volume apart from a subtle loss of grey matter in the medial frontal gyri. Given the modest nature of these findings, the routine assessment of insight in non-clinical populations of individuals with MCI is therefore not supported. Prospective data in larger samples, however, would be helpful to clarify this further and determine if impaired insight predicts brain atrophy and cognitive decline.

Whole exome sequencing of familial hypercholesterolaemia patients negative for LDLR/APOB/PCSK9 mutations.

BACKGROUND: Familial hypercholesterolaemia (FH) is an autosomal dominant disease of lipid metabolism, which leads to early coronary heart disease. Mutations in LDLR, APOB and PCSK9 can be detected in 80% of definite FH (DFH) patients. This study aimed to identify novel FH-causing genetic variants in patients with no detectable mutation. METHODS AND RESULTS: Exomes of 125 unrelated DFH patients were sequenced, as part of the UK10K project. First, analysis of known FH genes identified 23 LDLR and two APOB mutations, and patients with explained causes of FH were excluded from further analysis. Second, common and rare variants in genes associated with low-density lipoprotein cholesterol (LDL-C) levels in genome-wide association study (GWAS) meta-analysis were examined. There was no clear rare variant association in LDL-C GWAS hits; however, there were 29 patients with a high LDL-C SNP score suggestive of polygenic hypercholesterolaemia. Finally, a gene-based burden test for an excess of rare (frequency <0.005) or novel variants in cases versus 1926 controls was performed, with variants with an unlikely functional effect (intronic, synonymous) filtered out. CONCLUSIONS: No major novel locus for FH was detected, with no gene having a functional variant in more than three patients; however, an excess of novel variants was found in 18 genes, of which the strongest candidates included CH25H and INSIG2 (p<4.3×10(-4) and p<3.7×10(-3), respectively). This suggests that the genetic cause of FH in these unexplained cases is likely to be very heterogeneous, which complicates the diagnostic and novel gene discovery process.

The effect of a single nucleotide polymorphism of the CYP4F2 gene on blood pressure and 20-hydroxyeicosatetraenoic acid excretion after weight loss.

BACKGROUND: Genetic background partly determines the efficacy of interventions to lower blood pressure (BP). The CYP4F2 and CYP4A11 enzymes are renal 20-hydroxyeicosatetraenoic acid (20-HETE) synthases that regulate BP. Gene variants of CYP4F2 and CYP4A11 associate with hypertension and stroke. We showed that a gene variant of CYP4F2 but not CYP4A11 was associated with increased 20-HETE excretion and BP. AIM: To compare BP and 20-HETE responses in carriers of the CYP4F2 1347G/A polymorphism and controls CYP4F2-GG (wildtype), during weight loss. METHODS: Volunteers genotyped as CYP4F2GA/AA (n = 26) and controls genotyped as CYP4F2 GG (n = 27) were counselled to reduce weight for 12 weeks, followed by 4 weeks of weight stabilization. Weight, 24-h BP, pulse pressure and urinary 20-HETE were measured at baseline, 12 and 16 weeks. RESULTS: At baseline, SBP was (+1.7 mmHg, P = 0.047) in the CYP4F2 GA/AA genotype. Compared with baseline, weight fell by 3.9 kg, P = 0.0001, in both genotypes, and was maintained to 16 weeks. SBP fell by (-7.6 mmHg, P = 0.004) in both genotypes after 12 weeks. However, after weight stabilization, SBP was +3.6 mmHg, P = 0.004 in CYP4F2 GA/AA genotype. DBP and heart rate changed similarly over time. Pulse pressure fell with weight loss (P < 0.001), but was elevated in the CYP4F2 GA/AA genotype at all time-points (+3.1 mmHg, P < 0.001). Urinary 20-HETE was similar at baseline and 12 weeks but elevated in the CYP4F2 GA/AA genotype (P = 0.017) after weight stabilization. CONCLUSION: Maintenance of lower BP after weight loss is more difficult for carriers of the CYP4F2 G1347A polymorphism and may be related to increased arterial stiffness and increased 20-HETE synthesis.

Detecting familial hypercholesterolaemia in the community: impact of a telephone call from a chemical pathologist to the requesting general practitioner.

OBJECTIVE: To determine whether a telephone call from a chemical pathologist to the requesting general practitioner (GP) of individuals at high risk of familial hypercholesterolaemia (FH) increases specialist referral and detection of FH. METHOD: Individuals with an LDL-cholesterol ≥ 6.5 mmol/L without secondary causes were identified from a community laboratory; 100 cases and 96 historical controls. All laboratory reports (cases and controls) received interpretative comments highlighting FH. In addition, the cases' GPs received a telephone call from the chemical pathologist to highlight their patient's risk of FH and suggest specialist referral, whereas with the controls' GPs were not telephoned. RESULTS: After 12 months follow-up, 27 (27%) cases were referred to clinic compared with 4 (4%) controls (p < 0.0001). 25 cases were reviewed at clinic, 12 (48%) had definite FH and 18 (72%) had probable or definite FH according to the Dutch Lipid Clinic Network Criteria, 2 cases did not attend their clinic appointments. Genetic testing was performed in 23 individuals: 7 (30%) had pathogenic FH mutations. Genotypic cascade screening of 4 kindreds from the intervention group detected an additional 7 individuals with FH and excluded 5 mutation-negative family members. CONCLUSIONS: A telephone call from a chemical pathologist to the requesting GP of patients at high risk of FH was associated with significantly higher rates of FH detection and specialist referral. Over 70% of individuals with an LDL-cholesterol ≥ 6.5 mmol/L were diagnosed with FH. However, further investigation is required to improve the relatively low referral rate.

Detection of variations and identifying genomic breakpoints for large deletions in the LDLR by Ion Torrent semiconductor sequencing.

OBJECTIVES: The aims of this study were to 1) compare LDLR variant detection between Ion Torrent Personal Genome Machine (PGM) sequencing and conventional methods used for familial hypercholesterolaemia (FH) diagnosis i.e. exon-by-exon sequence analysis and multiplex ligation-dependent probe amplification (MLPA) and 2) identify genomic breakpoints for 12 cases of large deletions in LDLR previously identified by MLPA. METHODS: Thirty FH patient samples were selected, 22 with mutations previously determined. Primers were designed and optimised to generate six amplicons covering the entire LDLR and sequenced on a PGM. An additional twelve samples carrying MLPA variants were sequenced on the PGM followed by Sanger sequencing to establish the breakpoints. RESULTS: A total of 2179 LDLR variants were identified in the 30 samples, with 383 variants in the region sequenced that was common to both PGM and Sanger methods. Three discrepancies were identified; two of these were identified by visual inspection of the BAM files, whilst the remaining discrepancy was likely an artefact of the PCR approach. Approximate genomic breakpoints for the 12 MLPA variants were identified using PGM sequencing, and Sanger sequencing of these regions established causative breakpoints. Eleven different rearrangements/mutational events were found, with eight out of eleven occurring in Alus. Two of the three samples with exons 2-6del had identical breakpoints. Two samples with exons 11-12del had unique breakpoints, indicating separate ancestral origin or mutational events. CONCLUSIONS: This study showed that Ion Torrent PGM sequencing is an accurate and efficient method to detect LDLR variants while providing additional information such as genomic breakpoints.

A variant in LDLR is associated with abdominal aortic aneurysm.

BACKGROUND: Abdominal aortic aneurysm (AAA) is a common cardiovascular disease among older people and demonstrates significant heritability. In contrast to similar complex diseases, relatively few genetic associations with AAA have been confirmed. We reanalyzed our genome-wide study and carried through to replication suggestive discovery associations at a lower level of significance. METHODS AND RESULTS: A genome-wide association study was conducted using 1830 cases from the United Kingdom, New Zealand, and Australia with infrarenal aorta diameter≥30 mm or ruptured AAA and 5435 unscreened controls from the 1958 Birth Cohort and National Blood Service cohort from the Wellcome Trust Case Control Consortium. Eight suggestive associations with P<1×10(-4) were carried through to in silico replication in 1292 AAA cases and 30,503 controls. One single-nucleotide polymorphism associated with P<0.05 after Bonferroni correction in the in silico study underwent further replication (706 AAA cases and 1063 controls from the United Kingdom, 507 AAA cases and 199 controls from Denmark, and 885 AAA cases and 1000 controls from New Zealand). Low-density lipoprotein receptor (LDLR) rs6511720 A was significantly associated overall and in 3 of 5 individual replication studies. The full study showed an association that reached genome-wide significance (odds ratio, 0.76; 95% confidence interval, 0.70-0.83; P=2.08×10(-10)). CONCLUSIONS: LDLR rs6511720 is associated with AAA. This finding is consistent with established effects of this variant on coronary artery disease. Shared causal pathways with other cardiovascular diseases may present novel opportunities for preventative and therapeutic strategies for AAA.

Effect of B vitamins and lowering homocysteine on cognitive impairment in patients with previous stroke or transient ischemic attack: a prespecified secondary analysis of a randomized, placebo-controlled trial and meta-analysis.

BACKGROUND AND PURPOSE: High plasma total homocysteine (tHcy) has been associated with cognitive impairment but lowering tHcy with B-vitamins has produced equivocal results. We aimed to determine whether B-vitamin supplementation would reduce tHcy and the incidence of new cognitive impairment among individuals with stroke or transient ischemic attack≥6 months previously. METHODS: A total of 8164 patients with stroke or transient ischemic attack were randomly allocated to double-blind treatment with one tablet daily of B-vitamins (folic acid, 2 mg; vitamin B6, 25 mg; vitamin B12, 500 µg) or placebo and followed up for 3.4 years (median) in the VITAmins TO Prevent Stroke (VITATOPS) trial. For this prespecified secondary analysis of VITATOPS, the primary outcome was a new diagnosis of cognitive impairment, defined as a Mini-Mental State Examination (MMSE) score<24 on ≥2 follow-up visits. Secondary outcomes were cognitive decline, and the mean tHcy and MMSE at final follow-up. RESULTS: A total of 3089 participants (38%) voluntarily undertook the MMSE>6 months after the qualifying stroke; 2608 participants were cognitively unimpaired (MMSE≥24), of whom 2214 participants (1110 B-vitamins versus 1104 placebo) had follow-up MMSEs during 2.8 years (median). At final follow-up, allocation to B-vitamins, compared with placebo, was associated with a reduction in mean tHcy (10.2 µmol/L versus 14.2 µmol/L; P<0.001) but no change from baseline in the mean MMSE score (-0.22 points versus -0.25 points; difference, 0.03; 95% confidence interval, -0.13 to 0.19; P=0.726) and no difference in the incidence of cognitive impairment (5.51% versus 5.47%; risk ratio, 1.01; 95% confidence interval, 0.69-1.48; P=0.976), cognitive decline (9.1% versus 10.3%; risk ratio, 0.89; 0.67-1.18; P=0.414), or cognitive impairment or decline (11.0% versus 11.3%; risk ratio, 0.98; 0.75-1.27; P=0.855). CONCLUSIONS: Daily supplementation with folic acid, vitamin B6, and vitamin B12 to a self-selected clinical trial cohort of cognitively unimpaired patients with previous stroke or transient ischemic attack lowered mean tHcy but had no effect on the incidence of cognitive impairment or cognitive decline, as measured by the MMSE, during a median of 2.8 years. CLINICAL TRIAL REGISTRATION: URL: http://www.controlled-trials.com. Unique identifier: ISRCTN74743444; URL: http://www.clinicaltrials.gov. Unique identifier: NCT00097669.

Plasma total homocysteine is associated with abdominal aortic aneurysm and aortic diameter in older men.

OBJECTIVE: This study was conducted to determine whether plasma total homocysteine (tHcy) and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism are associated with abdominal aortic aneurysm (AAA) and aortic diameter. METHODS: This was a cross-sectional study set in Western Australia of 4248 community-dwelling men aged 70 to 88 years. Infrarenal aortic diameter was measured using ultrasound scan, tHcy was measured by immunoassay, and MTHFR 677T polymorphism was detected by polymerase chain reaction. RESULTS: Adjusted multinomial logistic regression analysis showed the odds of having an AAA (aortic diameter ≥ 30 mm) for men with high tHcy (≥ 15 µmol/L) compared with those with normal tHcy (<15 µmol/L) was 1.45 (95% confidence interval [CI], 1.10-1.91). Every 5-µmol/L increment in tHcy was associated with 0.15-mm (95% CI, 0.01-0.28 mm) increase in mean aortic diameter. The tHcy concentration was higher in MTHFR TT homozygote individuals than in wild-type CC individuals. There was, however, no apparent association between MTHFR C677T polymorphism with AAA (TT vs CC genotype: odds ratio, 0.97; 95% CI, 0.72-1.31) or aortic diameter (TT vs CC genotype: mean increment of 0.01 mm; 95% CI, -0.63 to 0.65 mm). CONCLUSIONS: Elevated tHcy is associated with the presence of AAA in older men. There is also a positive dose-response relationship between tHcy and abdominal aortic diameter. Longitudinal studies and clinical trials of lowering tHcy are required to assess whether these relationships are causal.