I’m talking chromosomes. As we all learned in middle/high school you are born with 46 chromosomes (23 from mom and 23 from dad). Those chromosomes make up who you are and what you’ll be. If you’re unlucky you’ll gain a chromosome that is a defect.

My dad and my sister both have inverted 8 chromosomes. That means their 8th chromosome is flipped in sequencing. I never really knew what that meant for them so this blog is going to explore the inverted 8 chromosome defect.

Through prenatal genetic testing, the doctors caught my sister’s abnormality and tested my parents for it. My dad carried the gene with him. At the time the doctors weren’t sure what exactly this meant because genetics hadn’t really dealt with it yet. When I kid I rationalized it as, the number 8 can be flipped upside down and look the same, so it is the same with a chromosome. It’s not. If you talked to or looked at my dad or sister you would think they were like everyone else. I thought the gene didn’t matter because I never saw a difference in them.

Remember in class how we talked about the women who smoked like a chimney and lived to 103, it was an anecdote unable to reject the null hypothesis. In this case the null hypothesis is that an inverted 8th chromosome does not affect a person, and my family’s anecdote can’t reject that. They are the exception.

What does the 8th chromosome do?

The 8th chromosome contains 146 million building blocks of your DNA. That number sounds astronomical, but compared to the rest of your DNA it only makes up about 5% of you. The 8th chromosome holds an estimated 20,000 to 25,000 genes; 700, of which, are suspected to be essential in making proteins for your body. Source. If you want to know some genes definitely related to the 8th chromosome click here.

The 8th chromosome is used to make many important mechanisms in the body. It forms a protein found in your neuronal nicotinic acetylcholine receptor, or the part of your body that sends chemical signals between nerves. Source. It also forms a part of the cone photoreceptor cyclic nucleotide-gated channel, which allows you to detect light. Source. It also makes proteins that hold blood cells together and are found in the brain and muscles. Source.

What does inversion mean and why does it happen?

Inversion doesn’t mean the whole thing is flipped upside down. It means that part of the chromosome was detached, flipped, then reinserted into the chromosome. Source.

Then there are a few ways that it can happen. You obviously have the parents being able to pass on a gene/chromosome directly; this is called translocation. Also, it is possible that a person could just so happen to be born with a genetic abnormality which can be influenced by mitosis, meiosis, maternal age and environmental surroundings. Source.

What does an inverted 8 do?

As is, the 8th chromosome is linked to some really nasty diseases and cancers with other abnormalities. The inverted 8 sufferers face many symptoms including: “severe intellectual disability, a thin or absent corpus callosum, weak muscle tone (hypotonia), abnormal curvature of the spine (scoliosis), and minor facial abnormalities. Some individuals with this condition may also have heart defects, underdeveloped kidneys, or eye abnormalities. Older individuals usually develop abnormal muscle stiffness (spasticity).” Source.

My sister suffers from scoliosis. My dad has spasticity in his right arm. Could it be linked or just coincidence?  

Not all people with the inverted 8 experience the same symptoms. It depends where on the chromosome and how much of it was inverted. People with the inverted 8p21 region on the chromosome are suspected to have more issues. Source.

In a recent study done by geneticists at the Università di Pavia, Italy, was done regarding the inverted duplication of chromosome 8 on the short arm. They look at regions 8p12 through 8p22. People with a change in the 8p21.1 area of the chromosome had an increase in GSR that resulted in “neonatal hypotonia, prominent forehead, large mouth with everted lower lip, abnormally shaped large ears, brain malformations and severe mental retardation.” Source.

What can we conclude?

We can conclude that my dad and sister most likely do not have an inversion of 8p21 which lowers their risk at major issues. However, looking at their scoliosis and spasticity, I believe those could be a connection to this chromosome. I would say my dad’s heart issues could be considered a symptom too, but that is nulled by his smoking habits that the doctors have diagnosed them as. I wonder if it’s possible that the chromosome makes it easier for him to have these problems from smoking.

I hope you learned something new from this, because it was an eye opener for me about my family.