Beyond Genetic & Prenatal Testing- Pre-embryo Testing – Hiding the Results From the Patient
Medviews (host of next weeks grand rounds) has an interesting post about the dilemmas of genetic testing for deadly diseases such as Huntington’s Disease (he has one error- he calls it autosomal recessive but it is actually an autosomal dominant disease).Â For those unfamiliar see notes from the Huntington’s disease society on testing.Â The issue is if you get a copy of the disease gene from a parent you will develop the disease – and it is an awful one.Â There is progressive motor and cognitive degeneration ultimately leading to death.
There was a wonderful and touching piece in today’s New York Times detailing a young woman’s life as she comes to grips with her family’s history of Huntington’s Chorea (HC), an inherited disorder striking a patient with dementia and muscular discoordination in mid-life.
Ms. Moser, in a poignant and courageous decision, decided to take a genetic test to see whether she would develop the disorder. Unfortunately, the result came back positive, which, because of its recessive genetic nature, meant that both she and her mother would have the disease. Ms. Moser has come to grips with the life-altering nature of the news. She will apparently not have children, and will continue to devote her working life to the care of HC patients.
You see the standard up until now has been that since there is no treatment, diagnosis is a death sentence.Â Would you choose to know you have it?Â How would it affect your life?Â Many at risk have chosen NOT to be tested (it is a 50:50 shot if a parent has it that you would get it).
What many don’t know is that the genetic puzzle is now even more complicated due to PGD- preimplantation genetic testing.Â In PGD a fertility doc like myself will have the patient undergo IVF.Â When the embryos are at the 3 day 8-10 cell stage we biopsy them, take a cell, and do a rapid genetic sequencing to look for the target gene- in this case Huntington’s.Â If that particular embryo is affected we choose not to place it back into the womb and instead choose and unaffected one.
Â What happens in Huntingtons where the patients often have chosen to not even be tested themselves?Â I have had these patients.Â We can do what is called “non-disclosing PGD”.Â Here, we go through the whole process but the results not shared with the patient (by their choice).Â We choose the unaffected one to replace and the patient does not know if there even were any embryos that were affected.Â Either they don’t have the disease (and all embryos are healthy) or they do have it (and we just did not put the affected ones back in).Â
Personally, I think I would want to know but then again I am not in their shoes.Â As it has been said- live each day as if it were your last.Â
More amazing is that this technique of PGD could potentially be used someday toÂ help eradicate single gene disease from the human genome.Â Do you think it should be used to rid the population of diseases?Â If so which ones?!
Read more about PGD and controversy surrounding it here