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Escape-P

Escape-P. Katrina Smith Trainee Genetic Technologist Merseyside and Cheshire Regional Molecular Genetics Laboratory. Introduction. CVS received for rapid aneuploidy analysis. Reason for referral: Exomphalus. DNA extracted using Qiagen EZ1 robot. CVS analysed by QF-PCR.

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Escape-P

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  1. Escape-P Katrina Smith Trainee Genetic Technologist Merseyside and Cheshire Regional Molecular Genetics Laboratory

  2. Introduction • CVS received for rapid aneuploidy analysis. • Reason for referral: Exomphalus. • DNA extracted using Qiagen EZ1 robot. • CVS analysed by QF-PCR.

  3. Molecular Genetics

  4. Cytogenetics • Full karyotype. • Poor sample: • Bloody. • Small amount of tissue. • Cultures grown up and 2 cell lines identified. • No normal cell lines identified. • 46,XX,del(18)(p11.2)[15]/46,XX,i(18)(q10)[5]

  5. Full Karyotype: Monosomy 18p Normal Del(18)(p11.2)

  6. Full Karyotype: isochromosome Normal i(18)(q10)

  7. A Second Look • Looked back at QF-PCR results. • Identified an extra peak on marker D18S391. • D18S391 only marker on p arm of chromosome 18. • QF-PCR performed with chromosome 18 mulitplex on original CVS DNA. • Multiplex contains an extra p arm marker and 2 extra q arm markers.

  8. A Second Look

  9. Amniocentesis • Molecular received a direct prep of the amnio and DNA extracted using Instagene method. • QF-PCR using chromosome 18 multiplex. • All q arm markers diallelic: No trisomy • Extra peak on D18S391 disappears. • Both p arm markers single peaks.

  10. QF-PCR of Amnio

  11. Amniocentesis • Full karyotype. • 2 independent cultures analysed. • 46,XX,del(18)(p11.2)dn • Monosomy18p- and no evidence of isochromosome previously seen. • Results consistent with QF-PCR.

  12. Amnio Full Karyotype Del(18)(p11.2) Normal

  13. Conclusion • Final molecular report: • Original CVS sample was consistent with the presence of confined placental mosaicism; normal cell line being present in the placenta and a monosomy 18p cell line being present in the fetus. • In summary, the result of all molecular genetic analyses are consistent with the presence of a deletion of at least part of the short arm of one of the chromosome 18’s (monosomy 18p) in the fetus.

  14. Monosomy 18p. • Deletion of the short arm of chromosome 18. • There is a wide range of clinical features which can vary in severity. • Clinical features include: • Mental retardation • Speech delay • Short statue • Holoprosencephaly • Ptosis • Behavioural disorders • Dystonia

  15. Confirmation • Pregnancy terminated. • Cord stump and placental tissue received.

  16. Lessons Learnt • This case highlighted the fact that the QF-PCR multiplex only contained 1 marker on the chromosome 18 p arm. • This was also the case for the chromosome 21 multiplex. • This is now highlighted on the analysis spreadsheet so that any possible future cases may be investigated sooner. • It also highlights the importance cell culture artefacts can have on chromosome analysis. • This case was a good example of molecular and cytogenetics working closely together.

  17. Acknowledgments Special thanks to: Emma McCarthy Victoria Stinton Tracy Horsedal Many thanks for everyone from the Merseyside and Cheshire Regional Molecular Genetics Laboratory.

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