1 / 18

A review of the Wilson disease service over the past 15 years

A review of the Wilson disease service over the past 15 years. Miranda Durkie Sheffield Diagnostic Genetics Service miranda.durkie@sch.nhs.uk. Introduction. Wilson disease (WD; OMIM#277900) is an autosomal recessive disorder of copper metabolism Hepatic and/or neurological presentation

loan
Download Presentation

A review of the Wilson disease service over the past 15 years

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. A review of the Wilson disease service over the past 15 years Miranda Durkie Sheffield Diagnostic Genetics Service miranda.durkie@sch.nhs.uk

  2. Introduction • Wilson disease (WD; OMIM#277900) is an autosomal recessive disorder of copper metabolism • Hepatic and/or neurological presentation • Treatable if diagnosed early • Over 500 mutations reported in all 21 exons of the ATP7B gene (Cu transporting ATPase) • Significant numbers of reported cases where both mutations cannot be identified (10-30%) • Lots of postulation about second WD gene but no mutations identified in candidate genes so far

  3. WD service at SDGS • WD service available since 1995 (part research) • National (and international) referrals • Published results from SSCP & confirmation DNA sequencing of 52 UK patients in 1999 with detection rate of 70% • SSCP/seq of 3 hotspot exons identified 60% of mutations in British cohort • DNA sequencing replaced SSCP in 1999 and stage 1 screen increased to 7 exons to pick-up 80% mutations • Stage 2 screen = sequencing of all remaining 14 exons

  4. Service Evaluation Aims • Determine mutation spectrum by sequencing • Determine mutation detection frequency in British referrals • Determine if further testing for deletions/duplications and promoter variants is warranted • Assess utility of 2 stage screening approach

  5. Cohort 1 A D B C

  6. Cohort 2 Long time lag between start of project in 2004 and completion of MLPA & promoter work in 2009 (limited resources) Therefore decided to look at 2nd cohort of referrals received between November 2004 and April 2009 Only included cases where 2 mutations had been detected and/or full sequencing had been carried out

  7. Cohort 2 F E

  8. Interesting Cohort 1 caseD • One patient homozygous for common p.His1069Gln, c.3207C>A mutation • Routine family studies in 1999 showed that Dad was heterozygous for this mutation but Mum did not have it • Reported as a possible whole exon deletion or primer SNP. • Alternative primers showed no primer SNPs • In 2007 MLPA kit available for ATP7B (P098 MRC Holland) • MLPA showed no deletion in Mum or index case • Used Promega Powerplex kit to check for sample mix-up

  9. Powerplex results D13S317 Index case 189 Dad 189 Mum 177;193

  10. Interesting caseD cont. • Used fluorescent microsatellite markers along length of chromosome 13 • Found 7 markers between 13q11 and 13q14.2 show biparental inheritance • 6 markers between 13q14.2 to 13q34 (inc ATP7B at 13q14.3) show non-maternal inheritance & inheritance of single paternal allele • Paternal segmental UPD confirmed resulting in autozygosity for p.His1069Gln mutation • First reported case of UPD13 with WD

  11. Putative promoter mutation - Case E Sardinian mutation c.-441_-427del15 c.-442G>A +1 ATG start Cullen et al Clin Genet 2003

  12. Alibaba analysis c.-442G>A Wild-type c.-442G>A YY1 = transcriptional repressor

  13. TFsearch results c.-442G>A Wild-type c.-442G>A

  14. c.-442G>A further studies • Family studies showed that it was inherited from Mum concordant with familial segregation • Not found on 188 normal chromosomes • Putative new binding of YY1/NF-muE1/GATA affecting normal TF binding?? • Needs further work

  15. Interesting cases F • 3 individuals found with 3 putative mutations each • 2 mutations in cis are all different & all missense • 1 is predicted to affect splicing • 1 previously reported case with 3 mutations in literature from isolated mountainous region of Crete with very high WD incidence • Important implications for staged screening & presymptomatic testing

  16. Mutation distribution • Previous SSCP study found mutations in exons 2, 8, 13-15 & 18-19 most prevalent (80%) = Stage 1 screen • However new data shows exons 2, 5, 8, 13-14, 18-20 most prevalent Old stage 1 New stage 1

  17. Summary • 117 different mutations, 36 novel, found in 191 patients • No deletions/duplications detected therefore MLPA is not warranted for routine diagnosis • One promoter variant found therefore promoter analysis is not warranted for routine diagnosis • 1st case of UPD13 found in WD • 2 missense mutations can occur in cis • 60% of negative stage 1 screens said “WD not likely” therefore staged screening warranted but stage 1 exons need to be adjusted • Of 186 patients with confirmed diagnosis of WD the mutation detection frequency is 98% • Second WD locus is unlikely

  18. Thank you! Royal Hallamshire Hospital • Oliver Bandmann • Stefanie Klass Sheffield Children’s NHS Foundation Trust • Stuart Tanner Other • EuroWilson for supporting EMQN WD scheme Sheffield Diagnostic Genetics Service • James Blackburn • Ann Dalton • Anne Goodeve • Ann Lee • Maria Panayi • Everyone at SDGS past & present who worked on WD

More Related