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Cardiac disease is genetically heterogeneous with genes associated with multiple cardiac diseases, multiple causal genes per disease, and often multiple variants in one or more genes contributing to disease presentation. Gene panel testing, either through a specific targeted design, or by virtual analysis from the exome/clinical exome is an ideal approach for genetic diagnosis and provides information regarding complexity of these diseases. Bristol Genetics Laboratory provides a targeted gene panel for paediatric cardiomyopathy (PC) (71 genes, Agilent SureSelect) and a variety of virtual gene panels from Agilent Focussed Exome; Congenital Heart Defect (CHD) (38 genes), Aortopathy (28 genes), Arrhythmia (54 genes), Cardiomyopathy (119 genes), Connective Tissue (42 genes) Molecular Autopsy (208 genes) and bicuspid aortic valve (8 genes). Whole clinical exome analysis (6110 genes) with phenotypic prioritisation of variants based on HPO terminology using Exomiser can also be performed for patients with complex phenotypes whose phenotype does not clearly fit into a pre-defined gene panel or for patients who tested negative for a specific panel. 133 patients have been tested, including newly diagnosed cardiac cases, patients negative for other cardiac gene testing, and patients who have phenotype/genotype incompatibility where contribution of more than one gene is suspected. 41/133 (30%) patients have at least one potentially pathogenic variant. 22 patients have multiple plausible variants. We present data from the cardiac cohort tested to date and cases illustrating the utility and complexity of gene panel testing for cardiac disease including; 1) A paediatric patient with Left Ventricular Non-Compaction (LVNC), dilated aortic root and sinus brachycardia heterozygous (on the PC 71 gene panel) for a novel TMEM43 variant c.994A>G, p.(Thr332Ala) of unknown clinical significance. Further testing using a bespoke 138 gene cardiac panel from the Focused Exome detected a novel splice variant in the HCN4 gene associated with LVNC and primary sinus brachycardia (Milano et al , 2014). This patient’s mother who has aortic dilation and regurgitation was heterozygous for the TMEM43 variant and the half-brother who also has dilated aortic root and LVNC did not carry either variant. 2) A large Dilated Cardiomyopathy (DCM) family with variable severity between family members, one affected cousin was heterozygous for a variant of uncertain significance in MYBPC3 c.3384G>C, p.(Glu1128Asp) and another affected cousin heterozygous for a truncating TTN variant, c.89244del, p.(Phe29748Leufs*7). Further family studies are ongoing. Detailed phenotypic assessment (using a clinical proforma) has been shown to increase diagnostic yield in patients with complex cardiac disease. Reference Milano et al. J Am Coll Cardiol 2014;64(8):745–56

Barth syndrome (BTHS) is an X-linked disorder characterised by cardiac and skeletal myopathy, growth delay, neutropenia and 3-methylglutaconic aciduria (3-MGCA). Patients have TAZ gene mutations which affect metabolism of cardiolipin, resulting in low tetralinoleoyl cardiolipin (CL(4)), an increase in its precursor, monolysocardiolipin (MLCL), and an increased MLCL/CL(4) ratio. During development of a diagnostic service for BTHS, leukocyte CL(4) was measured in 156 controls and 34 patients with genetically confirmed BTHS. A sub-group of seven subjects from three unrelated families was identified with leukocyte CL(4) concentrations within the control range. This had led to initial false negative disease detection in two of these patients. MLCL/CL(4) in this subgroup was lower than in other BTHS patients but higher than controls, with no overlap between the groups. TAZ gene mutations in these families are all predicted to be pathological. This report describes the clinical histories of these seven individuals with an atypical phenotype: some features were typical of BTHS (five have had cardiomyopathy, one family has a history of male infant deaths, three have growth delay and five have 3-MGCA) but none has persistent neutropenia, five have excellent exercise tolerance and two adults are asymptomatic. This report also emphasises the importance of measurement of MLCL/CL(4) ratio rather than CL(4) alone in the biochemical diagnosis of the BTHS.

Erratum to: J Inherit Metab Dis (2015) 38:279–286 DOI 10.1007/s10545-014-9747-y The original version of this article unfortunately contained a mistake. The reference by Whited is incomplete. The corrected reference is: Whited K, Baile MG, Currier P, Claypool SM (2013) Seven functional classes of Barth syndrome mutation. Human Molecular Genetics 22:483–492.

Paediatric cardiomyopathy (PC) has multiple genetic causes and can present in infancy with cardiac failure and sudden death. Within the Bristol Genetics Laboratory analysis of Barth Syndrome ( TAZ gene) is triggered by an abnormal cardiolipin ratio, but only 7% of referred cases are mutation positive. Next generation sequencing technology enables large sets of related genes to be analysed simultaneously. As considerable clinical and genetic heterogeneity exists within and between PC families, a one off cost-effective gene panel test helps diagnosis and elucidates complex clinical presentations. An Agilent SureSelect custom enrichment kit was designed to include 71 paediatric cardiomyopathy genes, with data analysis through an in-house bioinformatics pipeline (Broad Institute) and Geneticist Assistant (SoftGenetics). This assay has been validated and introduced into service as a United Kingdom Genetic Testing network (UKGTN) approved test. Validation involved two runs using 17 patients, including 14 with known pathogenic variants with100% concordance. The assay coverage at 30x was close to the predicted 99.7% at design with one exonic gap ( CTF1, exon 3). Since introduction into service 37 patients have been tested, including infantile/paediatric cases; patients negative for other genes and patients who have phenotypic incompatibility with their reported pathogenic variant where digenic inheritance is suspected. 32/37 (86%) patients have at least one potentially pathogenic variant. In onefamily with HCM, a MYBPC3 variant c.1505G >A, p.(Arg502Gln) and a previously reported NEBL pathogenic variant c.180G >C, p.(Lys60Asn) (nebulette protein) were detected in a severely affected male demonstrating that multiple variants can explain phenotypic severity. The utility of testing rare genes is exemplified by: 1) A teenager with LV dilation and FH of sudden death who was heterozygous for a RMB20 ( RNA binding protein) variant c.1907G >A, p.(Arg636His), previously reported with severe familial DCM; 2) a patient with congenital heart block, LV dilation and FH was heterozygous for a novel likely pathogenic MYH6 (alpha heavy chain subunit) variant c.3578C >T, p.(Ala1193Val). Furthermore, a novel heterozygous TTN A-band frameshift variant was identified in an infantile DCM patient; recent data suggests TTN frameshift variants have not been reported in infantile cardiomyopathy. Details of the validation of this technology, an audit of this patient cohort illustrated by interesting cases will be presented.

s / Atherosclerosis 231 (2013) e1–e10 e9 Lipoprotein apheresis was commenced in June 2012. Treatment is carried out via native veins bi-weekly using the Kaneka DHP DX21 whole blood system. This has resulted in an average reduction of 50.10% in TC, 52.97% in LDL and 55.91% in Lp(a). The plan is to increase the volume of blood treated at each session but he is unable to sit still for long enough to achieve this due to the xanthoma on his buttocks. He has been referred for urgent surgery on these lesions. Regular lipoprotein apheresis will hopefully further reduce the cholesterol level and xanthomata. However issues other than venous access can affect the ability to achieve optimum results. SMITH-LEMLI-OPITZ SYNDROME, CAUSED BY DEFICIENCY IN THE LAST STEP OF CHOLESTEROL BIOSYNTHESIS: THE BRISTOL UKGTN DHCR7 MUTATION SERVICE H. Sawyer *, M. Gable , J. Honeychurch , S. Burton-Jones , A.Y. Brown , M. Williams . Bristol Genetics Laboratory, North Bristol NHS Trust, Southmead Hospital, Bristol, UK; Biochemical Genetics Unit, North Bristol NHS Trust, Southmead Hospital, Bristol, UK * Corresponding author. Cholesterol is produced from lanosterol through a series of reactions in the post-squalene cholesterol pathway. Several human malformation syndromes are caused by defects at different points in the pathway resulting in deficiency of cholesterol and accumulation of precursors: Smith-LemliOpitz (SLOS), Lathosterolosis, Desmosterolosis, CDPX2, CHILD syndrome, SC4MOL, and Antley-Bixler. SLOS is an autosomal recessive disorder caused by a deficiency of 7dehydrocholesterol reductase (DHCR7) in the last step of cholesterol biosynthesis, resulting in low cholesterol and raised 7-Dehydrocholesterol (7-DHC) levels. The phenotype ranges from intrauterine lethality through to mild dysmorphism/mental impairment with a carrier frequency ofw3% in Caucasians. A combination of cholesterol deficiency and toxic effects of 7-DHC or derivatives is thought to cause the SLOS phenotype by affecting: structural lipids of membranes, steroid hormones, neuroactive steroids, oxysterols, bile acids and maturation of the embryonic signalling hedgehog family of morphogens. Biochemical services have been offered since 1995, however, results can be equivocal, carrier testing is challenging and not readily available in the UK. A UKGTN DHCR7 mutation analysis service was introduced in 2009 for: 1) diagnosis in biochemically equivocal/normal cases with a SLOS phenotype, 2) retrospective carrier testing of parents where no proband material remains, 3) cascade carrier testing. DHCR7 screening by sequencing (ABI3730) has detected 26 different pathogenic mutations (including 2 novel point mutations and a novel large intragenic deletion) in 31 clinically/biochemically affected cases with subsequent carrier status confirmation for 20 couples. 10 parents were found to be carriers where the foetus or deceased child had not been tested. 14 patients with family history and 6 population risk partners have also been tested. We present the clinical andmutation data of the broad phenotypic range of patients tested to demonstrate the utility of the DHCR7mutation service in facilitating diagnosis, identification of carriers, and possible genotypephenotype correlations. PATTERNS AND ASSOCIATIONS OF LOW DENSITY LIPOPROTEIN DURING AND AFTER PREGNANCY IN A SOUTHERN AFRICAN POPULATION D.M. Tanyanyiwa , P. Byrnes , S. Jones , A.D. Marais . Chris Hani Baragwanath Hospital, Chemical Pathology, University of Cape Town Health Sciences Faculty, Observatory South Africa; Department of Internal Medicine, Division of Lipidology, University of Cape Town Health Sciences Faculty, Observatory South Africa Small low-density lipoprotein (LDL) is atherogenic and is associated e.g. with hypertriglyceridaemia, obesity, metabolic syndrome and diabetes mellitus. This fraction has been reported in pregnancy hence this study investigated the prevalence of various species of LDL in pregnancy and the association of LDL species with plasma triglyceride concentration and apoE genotype. Four hundred and seventy two non-diabetic women were studied at antenatal clinics in Harare, after obtaining informed consent. Blood was taken during pregnancy (between 13-36 weeks) and at least 6 weeks after delivery. Enzymatic spectrophotometric methods were employed to measure plasma triglyceride, cholesterol, high-density lipoprotein cholesterol concentrations and LDL cholesterol was calculated. Nondenaturing gradient gel electrophoresis was employed to classify LDL species into 5 categories: A, AI, I, IB and B in decreasing sizes and genotyping of apolipoprotein E (apoE), which is necessary for catabolism of triglyceride-rich lipoproteins was done by polymerase chain reaction. Statistical analyses were carried out by non-parametric t-tests and contingency tables; significance was taken as p