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Lot's of Things to Think About
If you follow along on our Instagram or Facebook pages you have probably already seen the good news… that our first scan went surprisingly well (I say surprisingly, because after 4 miscarriages in a row I don’t exactly set too many expectations for myself when we go in for our appointments these days) but on this occasion, we were very pleased to see our little bean wriggling around and measuring 1 day ahead at 7 weeks and 6 days.
After the scan, we had a lengthy chat with our OB who indicated that we could probably be cautiously optimistic about the current pregnancy, given that we were close to 8 weeks and everything so far looks good. It doesn’t mean we’re in the clear, but it is a good sign at this stage.
We then went on to discuss what we would like to do in terms of tests to determine whether the baby has any disabilities.
If you have followed along on our blog for a while now, you may recall a while back that we saw a genetics counsellor who indicated that, based on the breakpoints on Sam’s chromosomes due to his balanced translocation, our chances of going full term with a baby who had disabilities was about 10%... so of course that is something we are concerned about.
My main concerns when it comes to disabilities are a condition known as 1p36 Deletion Syndrome and Down’s Syndrome, given that chromosomes 1 and 21 are involved in the balanced translocation.
In terms of Down’s Syndrome, I don’t think our chances of that would be any higher than the general population. In terms of the balanced translocation, if there was too much of chromosome 21 inherited by the baby, it would mean there wasn’t enough chromosome 1… which, from our previous experiences, we know causes an early miscarriage (for us, anyway).
On the other hand, if part of Chromosome 21 was missing, apparently it wouldn't really matter as people can exist as "normal" even with the whole short arm ("p" arm) of Chromosome 21 missing - which is the part of Sam's that is swapped with Chromosome number 1. Even so, in our experience, we have had 1 miscarriage where part of chromosome 21 was missing, but it meant that there was too much Chromosome 1, which also resulted in a miscarriage for us.
(If this all sounds super confusing, check out this video for a quick overview of how chromosomal translocations work)
I hadn’t heard of 1p36 syndrome myself until I did a search to find out what types of disabilities are possible with this condition, and what I found was pretty serious. Here is an excerpt from the Genetic and Rare Diseases Information Centre:
"1p36 deletion syndrome is a chromosome disorder that typically causes severe intellectual disability . Most affected individuals do not speak, or speak only a few words. They may have temper tantrums, bite themselves, or exhibit other behavior problems. Most have structural abnormalities of the brain, and seizures occur in more than half of individuals with this disorder. Affected individuals usually have weak muscle tone ( hypotonia ) and swallowing difficulties ( dysphagia ). Other features include a small head that is unusually short and wide; vision and hearing problems; abnormalities of the skeleton, heart, gastrointestinal system, kidneys, or genitalia; and distinctive facial features. 1p36 deletion syndrome is caused by a deletion of genetic material from a specific region in the short (p) arm of chromosome 1. Most cases are not inherited ; only about 20% of the cases of people with 1p36 deletion syndrome inherit the chromosome with a deleted segment from an unaffected parent. In these cases, the parent carries a balanced translocation , in which no genetic material is gained or lost.  There is no cure for this disease. Treatment depends on the symptoms, and may include rehabilitation/educational programs, antiepileptic medication, and standard treatment for heart, kidney, eye, hearing or bone problems."
Based on my own research, I think the chances of our baby inheriting 1p36 syndrome are unlikely (although not impossible) as, from what I can find, although this syndrome does involve the exact part of Sam’s chromosome 1 involved in the translocation… I think his breakpoint is just slightly too big to cause this issue.
My understanding is that this particular syndrome is caused by a break between two specific points on the short (p) arm of chromosome one, spanning a distance of what is known as 10.5MB in size… whereas Sam’s break is 11MB in size… cutting it pretty fine, so like I say, not impossible but I think based on 3 of our previous miscarriages being due to a deletion of chromosome 1 at a size of 11MB (and one due to an addition of chromosome one at size of 11MB) we can feel at least some degree of safety that it is unlikely, in our case, that a baby with this deletion would go to term.
Nevertheless, it’s not completely impossible, as people with this condition do exist, and it is not usually until birth that their deletion is discovered.
Which brings us to our next dilemma.
Which is, do we… do nothing and assume the baby is fine? Do we explore some non-invasive testing options, or do we opt to have either a CVS or Amniocentesis to find out for sure whether the baby has any abnormalities?
It might sound simple in theory, but it really isn’t that straight forward.
While a CVS or an Amniocentesis (basically a big needle that goes through your stomach to take a sample that can be used to test whether there are any genetic disorders) can tell us with pretty much 100% certainty whether the baby does have any abnormalities, both tests come with a degree of risk, and that risk is, that if we do have a healthy “normal” pregnancy we are potentially putting the baby at risk of miscarriage by undergoing those tests.
The risk involved with CVS is about 2% resulting in miscarriage (so that’s about 1 in 50) and the risk with Amnio is a little less (more like 1%).
There is also the timing issue to consider, which is that a CVS can be done at around 11-13 weeks, whereas an Amnio can’t be done until about 16 weeks.
Then there is the waiting period (which can be up to 2 weeks) for the results.
Depending on the outcome of the test results, and whether we were to decide to continue with the pregnancy if serious abnormalities were shown, that means that we would have to make a decision about what to do quite quickly (it is illegal to undergo a termination after 20 weeks in Australia without prior approval from a medical board).
That’s not to say we would make that decision. I can’t say we would know for sure what we would do unless we were in the situation, but it does mean we still have to consider all the possibilities.
My gut feeling, based on our previous experiences, if that if a pregnancy is progressing as expected, it is probably unlikely that there is an underlying abnormality lurking in the background…
…but in saying that I would still like to have some sort of evidence to back up my hunch.
So, we decided to look into non-invasive options (blood tests), and a friend referred us to what is known as a percept NIPT for pregnancies at risk of unbalanced translocations (crazy that such a thing would even exist, hey!?)
I made a call to the company who does this test, gave them all our info… and they got back to us to say that they think the breaks on Sam’s chromosomes are probably too small to give an accurate result… however, they did say that if I could send them more information about our miscarriages and the breakpoints of the chromosomes on those, they might be able to re-assess.
So, I have sent them all the info on each of the miscarriages and I should get an answer back by tomorrow…
I’m not really expecting that they will be able to do the test for us, but it is worth exploring just in case.
Which brings us back to our initial dilemma…. Do we do an invasive test (CVS or Amnio) or just run with the standard tests that are available and hope for the best?
We have a week until our next appointment at which point we will need to decide.
The risks involved with CVS and Amnio don’t sit all that well with us, so we’re probably leaning towards doing
as many non-invasive tests as we can and then, if any of those show any concerns, opting to do a CVS or Amnio… unless of course all the planets align and the percept NIPT suddenly becomes suitable for us.
No doubt I will keep hashing over all the possibilities in my mind over the next week.
Just as an interesting side note, when I was going back over our medical documents to send to the clinic, I noticed there had been an error when they told us the gender of our previous losses… instead of 3 females and 2 males, they were actually 2 males and 2 females (in that order) so the debate on whether Baby G5 is a boy or girl is back on! 😉
Until next time, there’s lots of things to think about… as always, feel free to comment with your thoughts below.
- Battaglia, A. (2013). 1p26 Deletion Syndrome. Gene Reviews. Retreived 29 January 2018 from: https://www.ncbi.nlm.nih.gov/books/NBK1191/
- Heilstedt, H. A., Ballif, B. C., Howard, L. A., Lewis, R. A., Stal, S., Kashork, C. D., Bacino, C. A., Shapira, S. K. & Shaffer, L. G. (2003). Physical Map of 1p36, Placement of Breakpoints in Monosomy 1p36, and Clinical Characterization of the Syndrome. American Journal of Human Genetics. 73(5). pp 1200-1212
- National Centre for Advancing Translational Science (2016). Chromosome 1p36 deletion syndrome. Genetic and Rare Diseases Information Centre. Retreived 29 January, 2018 from: https://rarediseases.info.nih.gov/diseases/6082/chromosome-1p36-deletion-syndrome
- Unique (2013). 1p36 deletion syndrome. Understanding Chromosome Disorders. Retrieved 29 January, 2018 from: http://www.rarechromo.org/information/Chromosome%20%201/1p36%20deletions%20FTNW.pdf
- Unique (2005). 21q deletions. Understanding Chromosome Disorders. Retreived 29 January, 2018 from: http://www.rarechromo.org/information/Chromosome%2021/21q%20deletions%20FTNW.pdf
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