Blog @ Illumina
Real scientists. Real commentary.

Stories of Hope for the Next Generation: Karyomapping PGD

Yara Shamsah
| Oct 18, 2015

Like most scientific techniques, karyomapping PGD (preimplantation genetic diagnosis) involves some complex and precise parameters, but it packs a punch when it comes to the impact it has in improving patient lives.

I’m referring to the recent articles describing several babies born free of specific genetic conditions because of PGD. Two families in Australia were able to ensure the respective genetic diseases they carried were not passed on to their children, thereby ensuring the protection of their family’s future generations. Hence the title ‘The curse stops here’. As background, let me start by briefly explaining what karyomapping PGD actually is and how it is used to ensure healthy futures.

Depending on severity, inherited genetic disorders can have a devastating impact on entire families, involving psychological, social and/or economic effects. Individuals carrying a trait for a genetic condition who have watched loved ones suffer through crippling conditions, often lose hope of starting a family of their own for fear of passing on the affected gene to their future children.

This is where an intervention can make a difference, providing certainty for couples at risk of transmitting severe genetic conditions to the next generation. Karyomapping is a PGD technique used in conjunction with in vitro fertilization (IVF). It works by finding unique genetic markers, like fingerprints, on the chromosome that carries the defective gene. Using these markers, it is possible to look at the chromosome segment in which the gene of interest lies, and determine from which parent that segment was inherited. This allows scientists to determine whether the embryo has inherited a normal or a mutated version of that gene, thereby identifying which embryo is affected and which is unaffected and likely to be a good candidate for transfer.

Embryos obtained by IVF undergo a biopsy step where one or more cells are removed and tested for a specific disorder. With this technology, prospective parents can test the disease status of their embryos before implantation and pregnancy.

In the cases mentioned above; one family was from Melbourne and the other from Sydney, but both sought treatment at Melbourne IVF. Mike and Victoria from Melbourne had treatment after they lost their first child, Charlie  to a hereditary condition known as Congenital Myasthenic Syndrome (CMS), a neuromuscular disorder characterized by weakness and fatigue that results from problems at the place where nerve and muscle cells meet. The couple were previously unaware that they were both carriers for the rare condition until the loss of their son. They chose to undergo karyomapping because they wanted to have another child, but wanted to ensure that this child did not inherit the condition.

By coincidence, the same day that Mike and Victoria’s healthy baby boy was born, a Sydney couple, Jono and Alex, had a healthy baby girl born free from her mother’s BRCA1 mutation. After discovering she had inherited her family’s BRCA mutation, Alex decided ‘the curse’ was going to stop with her, that she would be the last woman in her family to carry the gene. Although not all BRCA mutations are harmful, certain gene changes do have a profound impact by significantly increasing the risk of developing breast and ovarian cancer. Before having preventative surgery to reduce her chances of developing cancer, Alex wanted to start her own family. To ensure her baby didn’t inherit the mutation, the couple used karyomapping to select a mutation-free embryo.

This technique provides new hope to prospective parents who carry devastating hereditary conditions. It gives them the confidence that their children and future generations are protected from these conditions. For some, PGD is the only hope.