Researchers have now identified a new gene variation associated with early hair loss that can be inherited from either the mother or the father.

The link of male pattern baldness to the mother’s family was first described way back in 1916. It took until  2005 before German researchers identified a gene (labeled AR) on the X chromosome common to many bald men. Men inherit a single X chromosome from their mothers, and have a 50 percent chance of inheriting an AR gene for baldness if their maternal grandfather has it.

However scientists have always thought that other factors are also involved, since some men with the AR gene don’t lose their hair, and some who don’t have the AR gene still do go bald. A 2004 study found that men whose fathers had male-pattern baldness were approximately 2½ times as likely to have some level of hair loss than men whose fathers did not. This was irrespective of their maternal grandfathers.

The latest studies scanned DNA samples from large groups of men with male-pattern baldness and found genetic markers on chromosome 20 that weren’t present in control groups with abundant hair.

Humans get one copy of chromosome 20 from their mother and one from the father. Therefore gene variation for balding is neither dominant nor recessive, but additive. Men with one affected copy were three and a half times as likely to show early hair loss, and those with two copies were six times as likely to do so. The studies also showed that about one in seven Caucasian men have both the chromosome 20 variation and the AR gene, which increases their risk of early baldness seven times.

Finding the triggers for male pattern baldness allows the research into cures to stop the triggers from activating. It also raises the possibility of testing for male pattern baldness. This will allow you to see at an early age whether you have these genes, therefore letting you know whether you will suffer from baldness in the future.

If a man tests positive for a particular high risk genetic variant then he has about a 70% chance of going bald. Conversely, if he  tests negative then he has about a 70% chance of not going bald.

Once male pattern baldness becomes visible it usually means that a man has already lost a significant portion (up to 50%) of their hair already. As medications that combat hair loss are the most effective at stabilizing and reducing hair loss, rather than promoting hair re-growth, the earlier that the likelihood of suffering male pattern baldness is established, the better the chances are of saving your hair.

The test involves collecting a genetic sample via a cheek swab, and the test costs about $150.