In episode four*, I discuss the history, mission, and value of a great organization: Down Syndrome Affiliates in Action. More can be learned about DSAIA at this link. I hope you’ll listen and, then, I hope you’ll join us at the DSAIA annual conference.
Leave a comment sharing about Down Syndrome Affiliates in Action: your favorite conference, speaker, idea, or best talent show participant
*Despite welcoming listeners to “Episode Three,” this is the fourth episode. I hope you’ll listen to future episodes as well!
Hi Mark great article! How do I ask a question about odds of having a downs baby? My nuchal translucency test and anatomy scan all came back great but the California screening test (blood) came back a 1:85 chance for DS I’m freaking out! I have 3 other kids all normal however my husband has a severely autistic son. Anything to do with that you know of? Sorry if this is the wrong spot but I’ve been searching the internet for days looking for answers. Level 2 US scheduled for tomorrow.
I’m not sure if what you mean by the California screening test was in combination with the nuchal translucency test or is a separate cell free DNA screen. From the 1:85 chance reported, it suggests its just conventional screening, not cell-free DNA screening. A 1:85 chance means you have a 1.1% chance that the test is a true positive and a 98.9% chance that it is a false positive. If you have further questions about what the screen odds mean, I would ask your provider for an explanation, but feel free to check back here if that prompts additional questions. I am not familiar with any study that suggests your husband having a child with autism has any bearing on your chances for Down syndrome.
Thanks for the great website, Mark. I had a 20 week ultrasound that found CHD of AV canal defect, a plexus cyst and clenched fists. Took Matern21 bc the dr said this heart defect was associated with Down syndrome. The test turned out positive for abnormal results of Trisomy 18.
I’m 40 and this is my fifth child and have had several chemical miscarriages. Curious your thoughts? Is there any chance the baby could not have this and be “healthy”? Also, could the baby be born with Trisomy 21 instead of 18? Thank you so much for your response and time!
According to this online calculator, your MaterniT21 has around a 69% chance of being a true positive for Trisomy 21 and 31% chance of being a false positive. Based on those odds, you have almost a 1/3 chance that the test result is wrong and your child does not have Trisomy 18. Whether your child could be born with Trisomy 21 instead of 18, I have not seen research that would report on the likelihood of that happening. Instead, I would default to simply your age-related chance for having a child with Trisomy 21 which is roughly around 1%.
Mark, thanks for your reply yet again! – this PPV above was from calculator you have given. I’m not understanding why my Maternit21 Genome report gave a PPV of 52% for Trisomy 18. (as stated in my second post) Why is this different from that PPV calculator? This is so upsetting the lack of information people are receiving on this. Thanks so much!!
The online calculator is based on generally reported numbers whereas the MaterniT21 report is based on the information the lab has for its test’s performance. Since it would be in MaterniT21’s interest to quote as high an accuracy rate as possible, the fact that the reported number is even lower than the online calculator suggests it may be even more reliable.