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High resolution mapping of the X chromosome pseudoautosomal region in two siblings with Hodgkin Lymphoma and Leri-Weill Dyschondrosteosis. Kym Spencer Liverpool Women’s Hospital. Reed-Sternberg cells & Hodgkin cells. Clinical Features. Incidence. Cancer Research UK figures for 2004:
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High resolution mapping of the X chromosome pseudoautosomal region in two siblings with Hodgkin Lymphoma and Leri-Weill Dyschondrosteosis Kym Spencer Liverpool Women’s Hospital
Incidence • Cancer Research UK figures for 2004: • 1,519 new cases - 0.5% of all cancers diagnosed. • Incidence of 2.4/100,000 individuals • 2.7/100,000 males • 2.1/100,000 females • Bimodal age of incidence • 15-40 years • >55 years
A genetic cause of HL • Several familial cases of HL reported. • Risk of HL higher in individuals with a family history of the condition. • Higher in siblings. • Highest in gender concordant siblings. • Combination of inherited susceptibility with shared environment? • Male predominance of HL • Horwitz & Weirnik (1999 & 2007) suggest pseudoautosomal link due to recombination mechanism of pseudoautosomal regions.
Leri-Weill Dyschondrosteosis (LWD) Hodgkin Lymphoma (HL) Family L
p PAR1 PAR2 p q q X Y Pseudoautosomal Regions
Leri-Weill Dyschondrosteosis (LWD) Hodgkin Lymphoma (HL) 2 (GW) Family L
Methods • MLPA for SHOX copy number using P018B MLPA kit from MRC Holland • Fluorescent microsatellite analysis • Addition of custom probes into existing MLPA kit • SNP analysis • Microarray analysis
PR55 B α, β, γ or δ PR65 α or β PR61 B’ α, β, γ, δ or ε A PR72/PR130 B’’ or PR48 C PR93/SG2NA or PP2A B’’’ PR110/striatin α or β PPP2R3B • PPP2R3B encodes PR48. • B subunit of the PP2A holoenzyme. • Involved in cell cycle regulation - binds to Cdc6 in mammalian cells and restricts DNA replication. • PP2A is a cell cycle regulator and tumour suppressor. • Consists of A, B and C subunits. • B subunits confer substrate specificity.
CTCF • CTCF (CCCTC - binding factor) • Transcriptional regulator through • chromatin remodelling • epigenetic modification • control of transcriptional machinery • insulating promoter interaction with enhancers /silencers • Can bind to a diverse array of DNA sequences using different combinations of its 11 zinc finger domains CTCF zinc finger domain
Conclusions • Deletion of this CTCF binding site could affect regulation of its target gene. • Could the target be PPP2R3B? • Deregulation of PPP2R3B could result in deregulation of the cell cycle • Another B subunit of PP2A is present at 4p16.1, a region linked to HL in a study by Goldin et al. (2006). • The CTCF binding site could regulate another, more distant gene. • Further studies required.
Conclusions • Deletion of this CTCF binding site could affect regulation of its target gene. • Could the target be PPP2R3B? • Deregulation of PPP2R3B could result in deregulation of the cell cycle • Another B subunit of PP2A is present at 4p16.1, a region linked to HL in a study by Goldin et al. (2006). • The CTCF binding site could regulate another, more distant gene. • Further studies required.
Acknowledgements Thanks to the following people for their help: • David Gokhale • Vicky Stinton • G Malcolm Taylor • Ciaron McAnulty • Frances White • Una Maye • Julie Sibbring • Emma McCarthy • Roger Mountford • Andrew Wallace • Simon Thomas • Kevin Baker • Gareth Evans • John Radford • All at Liverpool Molecular Genetics Laboratory for their help, advice, interest and patience.
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