Male baldness - also referred to as androgenetic alopecia or male pattern baldness (MPB) - affects a significant number of people in the United States, as the condition accounts for over 95 percent of all hair loss in men.

According to the American Hair Loss Association, two thirds of U.S. adults will be affected by MPB to a certain degree by the age of 35, and around 85 percent of men will have experienced significant hair loss by the age of 50.

A lot of these men are seriously affected by the condition, which can have a negative effect on a person's self-image, as well as on their interpersonal relationships.

Additionally, some genetic studies have even associated MPB with negative clinical outcomes such as prostate cancer and cardiovascular disease.

A new study - led by Saskia Hagenaars and David Hill of the University of Edinburgh in the United Kingdom - explores the genetic basis for the condition. The findings were published in the journal PLOS Genetics.
 

Analyzing male pattern baldness in more than 52,000 individuals

Scientists analyzed the genomic and health data of more than 52,000 men enrolled in the UK Biobank - an international health resource offering health information on more than 500,000 individuals.

The team located more than 250 independent genetic regions linked to severe hair loss.

The researchers split the 52,000 participants into two groups: a so-called discovery sample of 40,000 people and a target sample of 12,000 individuals. Based on the genetic variants that separated those with no hair loss from those with severe hair loss, the team designed an algorithm aimed to predict who would develop MPB.

The algorithmic baldness predictor is based on a genetic score, and although accurate predictions are still a long way off, the results of this study might soon enable researchers to identify subgroups of the population that are particularly prone to hair loss.

In the present study, researchers found that 14 percent of the participants with a submedian genetic score had severe MPB, and 39 percent had no hair loss. By contrast, 58 percent of those scoring in the top 10 percent on the polygenic score had moderate to severe MPB.

Co-lead author Saskia Hagenaars - a Ph.D. student at the University of Edinburgh's Centre for Cognitive Aging and Cognitive Epidemiology - comments on the findings:

"We identified hundreds of new genetic signals," Hagenaars says. "It was interesting to find that many of the genetics signals for male pattern baldness came from the X chromosome, which men inherit from their mothers."

The study's other lead author, Dr. David Hill, notes that the study did not collect data on the age of baldness onset, but only on hair loss pattern. However, he adds that, "we would expect to see an even stronger genetic signal if we were able to identify those with early-onset hair loss."

To the authors' knowledge, this is the largest genetic study of MPB to date.

The study's principal investigator, Dr. Riccardo Marioni, from the University of Edinburgh's Centre for Genomic and Experimental Medicine, explains the significance of the findings:

 "We are still a long way from making an accurate prediction for an individual's hair loss pattern. However, these results take us one step closer. The findings pave the way for an improved understanding of the genetic causes of hair loss."