1 / 15

Alison Taylor Molecular Genetics GOSH

Mutation screening in patients affected with autosomal dominant hypercholesterolemia – results from the Department of Health Pilot Project. Alison Taylor Molecular Genetics GOSH. Autosomal Dominant Hypercholesterolaemia. Characterised by:

merv
Download Presentation

Alison Taylor Molecular Genetics GOSH

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mutation screening in patients affected with autosomal dominant hypercholesterolemia – results from the Department of Health Pilot Project Alison Taylor Molecular Genetics GOSH

  2. Autosomal Dominant Hypercholesterolaemia • Characterised by: • Increased plasma levels of total cholesterol and low density lipoprotein • Tendon xanthoma • Premature symptoms of coronary heart disease • Heterozygous form 1/500 • Homozygous form 1/1,000,000

  3. Autosomal Dominant Hypercholesterolaemia • Mutations in: • LDLR • Apolipoprotein B-100 gene (APOB) • Proprotein convertase subtilisin/kexin type 9 gene (PCSK9) • Majority of mutations in the LDLR gene – >1200 identified • Cascade testing is cost effective way to identify new patients

  4. Simon Broome Criteria • Simon Broome FH register criteria: • A) TC > 7.5mmol/l or LDL cholesterol >4.9mmol/l • B) Tendon xanthoma in patient or first degree relative • C) Family history of MI before age 50yrs in 2nd degree relative or 60yrs in 1st degree relative • D) Family history of TC >7.5mmol/l in first/second degree relative

  5. Dept of Health Project • Present data from a cohort of 635 patients with clinical diagnosis of heterozygous FH • Samples referred from six adult lipid clinics in UK • Patients classified using Simon Broome criteria • 190 definite FH (DFH) • 394 possible FH (PFH) • 51 unclassified (UFH)

  6. FH20 ARMS Kit • FH20 kit from Tepnel has 3 mixes (A, B and C) • Efficient and cost effective screen for FH testing • Doesn’t require specialised equipment, completed in 1-2 days • Used as initial screen • Multiplex ARMS analysis to detect 13 common mutations in familial hypercholesterolaemia Taylor et al Clinical Genetics 2007: 71: 561-568 p.Asp374Tyr p.Arg3527Gln p.Asp482His

  7. Point mutation screen • 18 exons and promoter region of LDLR gene • Initially done by SSCP, then dHPLC • Now – direct sequence analysis • Beckmann Coulter Robots • 20 fragments • 6 patients, 1 normal control and blank • 2 PCR plates – 4 sequence plates

  8. MLPA analysis • GeneMarker software (SoftGenetics)

  9. Results • Mutations found in 232 patients (36.5%) • DFH – 106 (55.8%) • PFH – 113 (28.7%) • UFH – 13 (25.5%) • Of mutations detected • ARMs – 43% • Point mutation screen – 52.3% • MLPA – 4.7%

  10. Results • 107 different mutations • 12% APOB p.Arg3527Gln • 5% c.654_656delTGG • 5% c.313+1G>A • 5% p.Pro685Leu • 1.7% p.Asp374Tyr PCSK9 • 6.9% novel – all predicted to impact on receptor function

  11. Cascade testing • All but one of the sites carried out cascade testing where a mutation found in proband • Cascade testing in 100 families • 290 relatives tested • Mutation found in 166 relatives (56.1%)

  12. Conclusion • NICE guidelines recommend that DNA testing is offered to all identified probands • Data presented strongly supports the clinical utility of DNA testing in patients with ADH • Overall detection rate in 635 patients was 36.5% • FH20 ARMs kit is an extremely efficient test in UK patients • 49% DFH • 38% PFH

  13. Conclusion • Mutation screening still required as 6.9% mutations novel • Even in subjects with low clinical suspicion of FH mutation testing will be useful

  14. RMG GOSH Gail Norbury Darrell Wang Brendan Martin Kunjan Patel London IDEAS Steve Humphries Ros Whittall Gretta Wood Mabella Farrer JE Cooper Gaye Hadfield Sarah Leigh Referring Centres RDG Neely S Fairgrieve D Nair M Barbir J Jones S Egan Y Lolin E Hughes Tepnel Diagnostics Dept of Health Acknowledgements

  15. I am running the London Marathon in April for Great Ormond Street Children's Charity www.justgiving.com/aetaylor

More Related