Q: There was a retrospective study by Lotufo et al. linking male pattern baldness to heart disease. Do you think there are other links like this for androgenetic alopecia? — J.L., San Francisco, CA
A: Family studies revealed both the androgen receptor locus on the X chromosome, as well as a new locus on chromosome 3q26. Association studies performed in two independent groups revealed a locus on chromosome 20 (not near any known genes) as well as the androgen receptor on the X chromosome.
So far, the genetic studies for androgenetic alopecia (AGA) have not revealed identification of a particular gene other than the androgen receptor, as well as the two candidate regions on chromosomes 3 and 20. Inasmuch as the androgen receptor can be involved in other diseases, this might be a feasible connection. Until candidate genes are identified that underlie AGA, it is impossible to predict where the commonalities might lie.
Excerpted from Angela Christiano, Hair Transplant Forum International 2011; 21(1): 14-15.
Read more about Hair Loss Genetics, and see some other Hair Restoration Answers posts on the topic.
Q: Is it worth getting the genetic test for balding?
A: You’re referring to Hair DX (hairdx.com), which costs about $150 and came to market in January of 2008 as the first test for androgenetic alopecia, aka male pattern baldness.
The test screens for variations in the androgen receptor gene on the X chromosome, the gene that is associated with male pattern hair loss. The purpose of the test is to identify persons at increased risk of developing hair loss before it is clinically apparent – so that medical intervention can be started early, when it is most effective.
It is important to realize that, at this point, there is just an association with this gene and hair loss; the cause and effect has not been proven and the association is not anywhere near 100%. A danger is that patients may overreact to the relatively incomplete information that the test provides. It is best to have the test performed under a doctor’s supervision, so that it can be put in the context of other information that the physician gleans through a careful history, physical and a densitometry hair evaluation. As of this posting, genetic testing for hair loss is not permitted in New York State.
Most medical conditions can best be addressed with early diagnosis. Genetic hair loss is no different. A test now has the ability to identify whether or not you may be genetically predisposed to hereditary male pattern baldness (Androgenetic Alopecia).
The HairDX genetic test offers information that can aid you and your doctor in making an informed decision about the treatment of your hair loss.
This test is not a substitute for an examination by a physician experienced in the diagnosis and treatment of hair loss. It offers one more bit of information that, in the context of other data (such as hair loss pattern, scalp miniaturization and family history) can help guide you and your doctor to formulate an appropriate treatment plan.
How does this test work?
This new genetic test examines genetic variables (SNP) which are responsible for recognizing Androgen hormones in our bodies. These specific genetic variants of the X chromosome (the Androgen Receptor or AR gene) are found in 95-98% of bald men.
These genetic differences are associated with Male Pattern Baldness (MPB) and by identifying them; the onset of MPB might be better predicted. If a person is predisposed genetically to these chromosomal variations, they may be more likely to develop male pattern baldness prior to age forty.
The test consists of a simple swab of the inside of your mouth. The skin cells are then sent to the HairDX clinical laboratory for a confidential analysis.
How accurate is the test in predicting baldness?
HairDX tests for a genetic variant of a gene (the androgen receptor gene) found on the X-chromosome that is present in more than 95% of bald men. Sixty percent of patients with this variant experience male pattern baldness before the age of 40. Therefore, if a person has this gene, they would have an increased risk of significant pattern baldness.
Another, less common genetic variant of the same gene (present in about 1 in 6 men) indicates a greater then 85% likelihood that a person will not experience early onset pattern baldness. If a person is found to have this gene, they are unlikely to become very bald.
Why is the genetic test not 100%?
The androgen receptor gene identified thus far is only one of a number of genes that affect hair loss.
How does the test compare to information obtained from a history and physical exam by your physician?
An assessment of scalp miniaturization by an experienced physician using a densitometer, combined with a history and physical, appears to be a far more reliable way of predicting future hair loss. The genetic test can complement this information, but does not replace it.
Q: What are the genes that cause male pattern baldness?
A: At this time the genes that actually cause hair loss are still unknown. However, there are two gene loci, recently identified, that appear to be associated with common baldness. The first is on the Androgen Receptor (AR) gene carried on the x-chromosome and the second is a non-sex chromosome 20p11.
Q: Why do some people have a full head of hair into their seventies or eighties and others start to go bald in their late teens or early twenties?
A: The cause is genetic and this poly-genetic trait can be inherited from the mother’s side, the father’s side, or both.
There is an old wives’ tale that it is inherited only from the mother’s parents. Although the inheritance can come from either side, it is actually greater from the mother’s side – but only slightly.
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