by Dr. Jenn Greenhall | C3 mutation, Concussion/TBI
My primary motivation for creating this blog is to educate people so they will find out whether they or their children have this mutation, which can be easily determined with AncestryDNA or the new 23andMe kit. But first, I’ll tell you about the gene, how I discovered I had this mutation, and its impact on my life.
Mutation in Complement Component 3 (C3) Is Discovered
The mutated gene is an immune gene called Complement Component 3 (C3 for short), and my particular autosomal dominant mutation (rs147859257, K155Q) occurs in about 1/180 people (~1.7 million people in the U.S. or ~40 million in the world) but is most prevalent in those with northern European ancestry and almost nonexistent in Asians.1,2,3 I learned I had this mutation when my genome was sequenced by Illumina as an adjunct to a Future of Genomic Medicine conference. Of the 20,000+ protein-coding genes in the genome, Illumina analyzed large chunks of 1690 genes causally related to disease, including C3 since it is definitively linked to Age-related Macular Degeneration (AMD) and other disorders.1,2
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by Dr. Jenn Greenhall | C3 mutation
The two cheapest tests that query the single nucleotide polymorphism (SNP) in Complement Component 3 that we’re interested in are AncestryDNA (regularly $99, but you can find occasional sales as low as $59) and 23andMe ($199 for health & ancestry, $99 for ancestry alone, often on sale for less). As of February 2018, FamilyTreeDNA does not query this SNP, though this is also a good company, especially for mitochondrial and Y-DNA sequencing. Ancestry queries 668,942 SNPs, and 23andMe queries 638,463 SNPs (based on our test results). Both will allow you to connect with DNA relatives, but Ancestry is more sophisticated and has a broad network linked to genealogical information if this is your primary interest. Though Ancestry will provide you with more specific information on your ancestral heritage, it will not specify health or trait information like 23andMe’s health version, which is limited but updates with new information from time to time. However, there are many programs online that can extract much more health and trait information for a minor cost ($25+, to be discussed in a later post) if you prefer the cheaper price and more specific ancestral information of AncestryDNA or the ancestry only version of 23andMe. They are both good companies, so it’s up to you.
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by Dr. Jenn Greenhall | C3 mutation, Cancer, Concussion/TBI, Dementia, Inflammation
Since learning I had this mutation (rs147859257) in Complement Component 3 (C3), many people in my family have tested their DNA to determine whether they share it as well. From analyzing which diseases and conditions people with the mutation have or had and excluding diseases also present in those who do not have the mutation, we’ve been able to postulate some disease associations. These associations are purely hypothetical at this point and mostly include diseases that could occur due to excessive inflammation. If you or others in your family have the C3 mutation, I would be interested in knowing if any of these diseases or others commonly occur in those with the mutation in your family. I am also considering organizing a study (though I still need to figure out the logistics). Please contact me if you’re interested in a study or just want to add to the information below.
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