Checking Your Carrier Status for Rare Genetic Diseases

The term “carrier status” when applied to a genetic disease usually means looking at whether or not you are heterozygous (have one copy) for a mutation that causes a Mendelian genetic disease.

In general, these are the rare genetic diseases that you would need two copies of the mutation in order to have the disease.

Take cystic fibrosis as an example… the Cystic Fibrosis Foundation explains that “People with CF have inherited two copies of the defective CF gene — one copy from each parent.  Both parents must have at least one copy of the defective gene.  People with only one copy of the defective CF gene are called carriers, but they do not have the disease.”

It is also important to know that researchers are discovering new things all the time about rare genetic diseases, such as this Nature article that looked at over 500,000 people’s genes and found that there are people that have a mutation for a genetic disease without symptoms.  This is a fairly new science, and researchers are still making discoveries all the time.

So with all the caveats above, why even look into your carrier status for genetic diseases? If you have kids already, it may be important to let them know if they are possibly a carrier for a genetic disease. Others in your family may also be affected.

Autosomal Recessive vs. Autosmal Dominant:

For most of the diseases listed below, being a carrier generally means you are not affected by the disease, but for some diseases, it is possible to be mildly affected.

In general, when someone is heterozygous, the normal, healthy allele (version from one parent) can compensate for the allele (version from the other parent) that isn’t working. But take hemochromatosis as an example– it is possible for someone who is heterozygous to have health issues from excess iron absorption before they reach the point of diagnosis of hemochromatosis, such as when their liver fails.

For more information on inheritance, www.yourgenome.org has a nice explanation.

The list below is not a complete list of all genetic diseases. It is for informational purposes only.  23andMe data only covers a small percentage (less than 1%) of your genome, and this is just a list of SNPs that I’ve compiled along the way.

Some of these mutations are also on the 23andMe health report (FDA approved) if you have purchased that, but there are several listed below that aren’t included in their reports.

Rare disease mutations aren’t all that rare:
If you consider that there are more than 7,000 rare diseases and that they affect 1 in 10 people in the US, it really isn’t out of the realm of possibility to be a carrier or affected by a rare disease.  Learn more at Global Genes or the National Organization for Rare Disorders.

Genetic mutations, carrier status:

Note that all of the risk alleles are listed in the FWD orientation to match with your results on 23andMe or AncestryDNA. If you are using data from another source, you should check to see if it is all listed in the FWD orientation.

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Related Articles and Topics:

Alpha 1 Antitrypsin Deficiency:
Find out more on A1TD, check your genetic data, and learn about the effects from carrying one copy of the mutation.

Cystic Fibrosis Mutations:
Check to see if you carry a mutation linked to cystic fibrosis.