It’s all in the DNA……..

I have always had a fascination with genetics and it was this that made me choose to study molecular and cellular biology at university. At this time (the early 1990s) The Human Genome Project started which was the first attempt to sequence an entire human genome. The technology at the time was limited and the project took 13 years to complete. Fast forward to today and it is now possible for anyone to spit in a tube and get their genome sequenced in a mere 6 weeks. My youngest daughter Katherine had her genome sequenced last year and the results we sufficiently interesting enough for me to want to do the same.

The information that you can get from genome sequencing comes in three sections:

• Ancestry Composition

• Carrier Status

• Health Traits

My ancestry composition can be seen in the diagram below:

The first surprise was that I was only 51% British. Through my genealogy research I’ve known for a while that many of my ancestors came from France but my DNA shows that I also have ancestors from Germany. In particular 10.5% of my DNA comes from the Ashkenazi Jewish population that settled along the river Rhine in the Middle Ages. It is thought that this population consisted of around a mere 330 individuals. In scientific terms this is called a genetic bottleneck. I will never be able to prove it but I suspect that this ancestor was through my maternal grandfather’s mother (my great grandmother). When looking at photos of Ashkenazi Jews there are some striking similarities in appearance to her. I am so proud to be 10.5% jewish as I have had done a lot of research into jewish culture over the years.

Katherine’s results showed that she was a carrier of the extremely rare genetic disease Zellweger Syndrome Spectrum. My results confirmed that she inherited this allele from me. Zellweger Syndrome Spectrum, as the name suggests covers disease with varying severity. The gene itself (the PEX gene) codes for a protein that is part of the structure of the intracellular organelle called the peroxisome. The peroxisome is involved in the cutting of long chain carbon molecules (e.g. fatty acids) which are then used by the mitochondria to create energy for the cell. The more severe cases of Zellweger Syndrome are invariably fatal within the first year of life. There hasn’t been anyone in my immediate family that has had a child with Zellweger Syndrome. Thankfully it is extremely rare. For comparison, the prevalence of cystic fibrosis is 1 in 2500 births; Zellweger Syndrome is 1 in 50,000 births.

Katherine was also found to have two copies of a gene for a condition called haemochromatosis which is an iron overload in the blood. Obviously one of these genes came from me. Fortunately the particular gene variant we have does not put us at an increased risk of developing the disease. This result was a bit ironic as David’s grandfather actually had haemochromatosis and he has been having blood tests every five years to check for iron overload and we now know that he is not at an increased risk of developing this condition.

The only results that were particular to me was a slightly increased risk of developing late onset macular degeneration and Alzheimer’s disease. I also have a 20% chance of developing type 2 diabetes. My recent diet changes will probably be enough to mitigate this risk. I was also relieved to find that I do not have a genetic predisposition for bowel cancer. I have had relatives on both sides of my family die from this cancer.

All in all I am really heartened by the findings in my genome. I was also able to download the raw data (genomic sequence) in file which I can use in third party programs. The company I used will also update me as more genes are identified so this is an ongoing quest.