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Genetics/Genetics question


QUESTION: Hi, I am wondering if I need to see a genetics counselor. My ob/gyn doesnt seem to think its necessary. Although I trust my doctor (he's a well respected Dr in Chicago) I'd like to have a second opinion.
Here's my situation. When I was 32 and we began trying for children I had a miscarriage. They didnt do any testing as it was my first one. Then, I had another one. They tested and it came back something like I had an extra "X" chromosone or whatever it was, not to worry. I then had 2 healthy boys back to back. Fast forward a few years, I just turned 37 and we are trying to conceive again. I've had TWO back to back miscarriages and both have come back after testing to be a result of chromosone 16. My dr seems to think this is just bad luck and old age but I am wondering if there is a bigger issue. I'd like to keep trying, especially if the odds are everything will be ok next time. Just wondering if I should trust my doctor and keep trying or seek the advice of a genetics professional (something I am not sure my insurance would cover). Thanks in advance. PS... Sometimes I dont get the emails that the question was answered and therefore it wont let me rate. I will check back periodically to see if there is a response. thanks in advance.

ANSWER: Hi Julie,

Thanks for your questions.

It would easy for me to provide you with the best solution if I had more information. But based on your description...
It is hard to say what was the cause of your miscarriages the first two times and the last two times. In the beginning of your question, you described something about the "X" chromosome.  
I am wondering (1) if this test was done using your peripheral blood or was it done on the miscarried fetus/abortus and (2) what was the karyotype. I know the latter would be sensitive information. But if answer to (1) is peripheral blood, and to (2) is presence of an alteration/variant in the karyotype, then I would suggest seeking a genetics professional's advice.  
If the answer to (1) is abortus, then you dont have to see a genetics professional's advice. I think in all probabilities this is the case.
That said, it is true that for women over 35 y of age, the likelihood of conceiving fetus with altered genetic components is higher, as the eggs of women are as old as the woman and events of maturation happen every month. The older the woman, the greater the chance of mistake in the maturation event.  Again, the later miscarriages related tests were I assume on the abortus and something was off regarding chr 16. This is likely again an age related event.

One final recommendation: You might want to consider IVF which has the best chance of conceiving a healthy child. But insurance may not cover these procedure.

Hope this answers your question,



---------- FOLLOW-UP ----------

QUESTION: Thank you so much for your time. To clarify... yes, testing was done on the tissue for miscarriages, 2, 3 & 4. I believe that was also called karotyping because I remember hearing that term? #2 was as a result of some trisomy that my dr said was common in miscarriage and not too worry (but it wasn't trisomy 16). The 3rd and 4th miscarriages were BOTH due to trisomy 16 which he said, again, weren't compatible with live birth and common for miscarriages. What worried me is I read somewhere it would be very unlikely to have two back to back trisomy 16 miscarriages so I worried. Does everything above make sense and does that mean that you do not think seeing a geneticist is necessary at this point as my dr still feels? I've also thought about IVF, but yes, its very expensive. I've gotten pregnant very easily so I almost feel like odds are this next time, it should work out?!
thanks in advance...

Hi Julie,

Thanks for clarifying.
Yes, you are correct that it is not very common to conceive fetus with trisomy 16, consecutively. Which means there is a scientific reason and I would like to slightly venture into a bit of genomics/genetics.
Age as you know is one determining factor which reduces the efficiency with which the cells divide. So they are likely to make mistake. This applies to the ova/egg as well as sperms. As a result, the egg that is ready for fertilization by a sperm may end up having the wrong number of chromosomes. Some chromosomes like 21, 16, 18 and 13 are most prone than others. When this egg gets fertilized, the fetus will be carrying a fatal loss or gain of chromosomes that will be incompatible with life. This can also happen when sperms end up having wrong no. of chromosomes - again due to age of father or some environmental agent. In such cases, the abnormality will show a somewhat random pattern.

But when a specific chromosome shows trisomy in a recurrent manner, there can be other reasons.
One, at a molecular level, specific gene(s) responsible for ensuring the correct segregation (distribution) of the chromosome in the egg is not functioning optimally in either one of the partner. This is hard to identify and not possible to run a panel of tests.

Two, one of the partner is carrying what is called a "balanced chromosomal rearrangement". In such case, either of the partners could be carrying a type of structural genetic alteration without losing or gaining genetic material. So the sum-total is equivalent to a normal genomic content, although a deviation from normalcy has occurred in the form of re-arrangement between two or more chromosomes. This will not affect the carrier and the carrier may never know of it until a recurrent fetal loss is encountered. In such cases, the re-arranged chromosomes can hinder the normal distribution of chromosomes leading to loss or gain of whole chromosomes in the egg/sperm. Thus a trisomy can result, other times monosomy or some thing else other than the normal two (a pair).

So depending on what rearrangement has occurred in either of the parent, the possibility of trisomy 16 or other chromosomes is highly likely. As I am not sure if you or your partner had a constitutional karyotyping, I cannot comment on this. This test can be done using peripheral blood and can rule out this possibility. A genetic counselor can then give you the best way to proceed.




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Thanemozhi Natarajan


Answers in Genetics, genomics, cytogenetics of syndromes, congenital anomalies, cancer, clinical genomics and interpretation of omics data.


More than 10 years. Doctoral research thesis on Congenital anomalies and cytogenetics, Recurrent reproductive failure and chromosomal abnormalities. Postdoctoral experience in Breast cancer research. Current: Clinical Genomics and Pharmacogenomics.


Cancer Cell International, Cancer Epidemiology Biomarkers and Prevention, Breast cancer research and treatment, Indian Journal of Pediatrics, BMC Proceedings, Pharmacogenetics and Genomics, Human Molecular Genetics, Frontiers in Genetics, Cancer Biomarkers.

PhD Biomedical Genetics

Awards and Honors
University Grants Commission Award for pursuing PhD level research (India); Travel awards to attend conferences.

Past/Present Clients
Post doctoral experience Cancer research, molecular epidemiology Current: Clininical Genomics and Pharmacogenomics

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