Understanding Genetic Testing & Sequencing – It’s Greek To Me
We have recently learned from the Mayo Clinic that our twins Addi and Cassi have one Niemann Pick Type C gene mutation that has been identified in their bodies — it’s called Exon 12 DNA Change 1920delG. This DNA sequence change (or deletion) is a “known pathogenic mutation in the sterol-sensing domain.” The 1920delG mutation leads to a premature stop in the synthesis of the protein after 655 residues, instead of the normal 1278 residues. We were told that because of the position of Addi and Cassi’s mutation, the lab at Mayo could only get clean DNA sequencing in the forward direction. We are still trying to figure out what all of this means.
The second mutation in the twins have so far has proved elusive to Mayo Clinic researchers. At this point, Hugh and I need to have our Niemann Pick Type C genes on Chromosome 18 sequenced in order to try identify our family’s second mutation. Next week, we will have our blood drawn and sent to Mayo for analysis and hope to find the second mutation. By finding our genetic mutations, we can learn clues about Niemann Pick Type C disease. We have also found out that Addi and Cassi do not have a common NPC mutation — that mutation is called I1061C. It gets more complicated for us and the mystery deepens.
I wonder if I have the Exon 12 DNA Change 1920delG in my body? Or is Hugh the carrier of this faulty gene? Which one of us has the gene that is proving elusive and hiding? How did this even happen to us and our family? This mystery goes back thousands of years and is so bizarre and so complicated that I simply don’t want to think about it anymore tonight. God only knows what will happen in my dreams. Each night, I am afraid to close my eyes for fear as to how my unconscious mind will take over — my nightmares are beyond comprehension.