Paisu Tang1, Andrea P. Twomey, Anke E. Kohfahl, Sharyn E. Stock-Myer
1 Virtus Diagnostics, Melbourne IVF, 344 Victoria Parade, Victoria, 3002
The most effective treatment option for many acquired and inherited paediatric haematological disorders is Haematopoietic stem cell transplantation (HSCT). Preimplantation genetic diagnosis (PGD) for HLA typing is an established procedure for assisting a couple to have a healthy sibling who can donate cord blood or haematopoietic stem cells to an ill child. PGD-HLA in Australia is performed under guidelines provided by the NHMRC.
Traditional PGD for HLA typing involves the search for informative STR markers and the establishment of a family-specific multiplex PCR test. While effective, this method typically requires a significant investment of time which is often precious in the case of acute haematological failure such as leukaemia and aplastic anaemia.
The recent availability of Karyomapping, a high resolution SNP array system, has dramatically reduced the test development time in PGD for HLA typing and single gene disorders. Karyomapping eliminates the need for patient-specific tests and allows for the simultaneous analysis of multiple loci and chromosome copy number for all 24 chromosomes in the human genome. Thus it is possible to diagnose the HLA compatibility, mutation status and aneuploidy status of an embryo within the one test.
We report on the application of Karyomapping for beta thalassaemia and HLA typing in 3 families. Each couple had one child affected with beta thalassaemia and their eligibility for PGD-HLA was assessed by our Reproductive Services Clinical Review Committee according to NHMRC guidelines. Overall, a total of 17 embryos were tested with a diagnostic efficiency of 100%. One family delivered a healthy HLA-matched child, one family has an ongoing pregnancy and the third family is yet to produce a genetically suitable embryo. We discuss the benefits and limitations of Karyomapping for PGD-HLA.
PhD in Genetics, have been working as a PGD scientist at Virtus Diagnostics-Melbourne IVF for 8 years.