The picture shown above is what chromosomes look like when they give you a copy of a genetic study. This specific picture is of Thomas’s chromosomes! These little squiggly things are what gives Thomas his blue eyes, strawberry hair, and yes, Down Syndrome! I’ve pointed out the 21st set of chromosomes, but notice that they aren’t a pair like the rest of them, they’re triplets. This is what makes a trisomy! Three copies of one chromosome! That’s why Down Syndrome is also referred to as Trisomy21. But, did you know there are other types of Down Syndrome?? All together there are three different types of Down Syndrome; trisomy21, full Down Syndrome, but you also have Translocation and Mosaicism.
Translocation is a type of Down Syndrome where the third copy of chromosome 21 attaches itself to a different set of chromosomes, more often than not its chromosome 14. The thing that sets Translocation apart from the other two types of Down Syndrome, is that it can be inherited from a parent. When the genetic study is done on the child with Down Syndrome and Translocation is discovered, the parents genes are often examined to determine if it was inherited. (1) If it was inherited, the parent will show 45 chromosomes in each cell they are made up of, but because they still only have two copies of each chromosome they are normal and healthy. Translocation in a parent is a rearrangement of chromosomes, and they are said to have “balanced translocation” or be a “balanced translocation carrier” if they show no extra or missing chromosomal material.
Mosaic Down Syndrome, though rare, is where the some cells of the body contain only two copies of chromosome 21 but others will contain three copies of 21, trisomy21. Mosaicism gets its name from the tile art style, because not all cells are the same. People with Mosaic Down Syndrome may have some features that look like traditional Down Syndrome, but won’t show them all. In fact, even people with traditional Down Syndrome may not show all the telltale signs!
Signs of Down Syndrome
Many parents can now be told during pregnancy if their child(ren) will have Down Syndrome. Non-invasive genetic testing can give pretty clear and accurate results! A non-invasive genetic test usually is brought up if there are signs on prenatal ultrasounds that may indicate Down Syndrome. Some of these signs may or may not include: a thickness in the nuchal fold, echogenic bowel, short “long bones” (the bones in our arms and legs), “flattened” facial profile, low muscle tone indicated by low fetal movement during bio-physical profiles and non-stress tests. There are some rare cases, like mine with Thomas, that even with some of these signs a diagnosis of Down Syndrome gets missed. I did have genetic testing done, after three inconclusive ultrasounds measuring the nuchal fold we decided to do a non-invasive genetic test while I was pregnant. Unfortunately, that test came back wrong. With 99.6% accuracy, the results stated that Thomas DID NOT have Down Syndrome. Throughout the course of my pregnancy he showed other signs, echogenic bowel on one ultrasound (it had disappeared by the next ultrasound) and short long bones were consistently noticed. He, however, did not show evidence of low muscle tone and still doesn’t! He, also, never showed signs of a flat facial profile. My high risk OBGYNs were baffled when we came to visit after he was born and I showed them his postnatal genetic study.
Even if signs during pregnancy get missed, a child born with Down Syndrome will often show signs immediately. Most of these signs include: elongated head, off-center hair swirl, upward slanted eyes, sandal gap, flat facial profile, excessive skin on the back of the neck, simian crease in the hands, low muscle tone, Brushfield spots in irises, and abnormal ears. These signs are the most common but they are not always present. Thomas, for example, does not have a simian crease, Brushfield spots in the irises, and hasn’t shown any signs of low muscle tone. He does have slightly upward slanted eyes, thickness at the nuchal fold (excessive skin on the back of the neck) and the sandal gap between his toes.
Alright, so I’ve explained the science part of Down Syndrome, but some of you may still be wondering: What is Down Syndrome??? I can definitely tell you, it is NOT a life without love. All of the people I have encountered with Down Syndrome, Thomas included, have been the most caring and loving people. They are smart and witty, silly and playful, kind and happy people. They have infectious smiles and great senses of humor! They are not their disability. They are business men and women, they advocate for themselves and others, they treat everybody equally. We should always follow their example.
If you have a loved one or know someone with Down Syndrome, help them celebrate their day! World Down Syndrome Day is March 21st! Wear crazy socks, go get some great products from Designs by Candie over on Etsy! Show them all love!
Be on the look out for a special treat from me and Thomas on 3/21! We can’t wait to celebrate with you all!
Love you all,
Sourses: (1) Translocation