Researchers are reporting that they've linked a gene to a rare condition that makes people develop thin "peach fuzz" hair, potentially paving the way toward greater insight into the hair loss phenomenon known as androgenetica alopecia, or male-pattern baldness.
The finding won't immediately lead to a better treatment or cure, said Angela M. Christiano, co-author of the study, published in the journal Nature. And though it's "just a tiny little piece of the puzzle," it could provide perspective about a component of male-pattern baldness known as shrinkage, said Christiano, director of the Centre for Human Genetics at Columbia University.
Contrary to popular belief, male-pattern baldness doesn't cause hair to stop growing. Instead, hair still grows but it's short and fine, like peach fuzz, Christiano said.
"If you look at a very bald scalp, they are still making tiny little peach-fuzz hairs," she said. "A follicle is still there. The hardware is still there to grow a hair of some kind."
People with a rare condition called hereditary hypotrichosis simplex have the same problem, although it begins at birth.
How the study was done
In the new study, Christiano and her colleagues examined the genetic makeup of members of two Pakistani families and one Italian family whose members have inherited the condition. The researchers discovered a gene in which a mutation appears to cause the problem.
The gene, called APCDD1, is located in a region of chromosome 18 that has been shown in previous studies to be linked to other forms of hair loss. The researchers also found that APCDD1 inhibits a signaling pathway that has long been shown to control hair growth in mice, but has not been extensively linked to human hair growth.
In addition to providing more insight into hereditary hypotrichosis simplex, the gene research "gives us an inroad into understanding male-pattern baldness" because the conditions are similar, Christiano said. It may be a matter of reprogramming the hair software because the hardware is still there, she said.
Part of the challenge of studying baldness is that mice don't suffer from the equivalent of male-pattern baldness, making animal research less effective in understanding how hair growth works, she said.
50% of over-50s have hair loss
Dr Doris Day, a dermatologist in New York City, said that about half of people older than 50 have hair loss. "It can be debilitating, especially to women, who have fewer options for treatment," Day said.
Drugs such as Rogaine and Finasteride (Propecia) treat baldness, but they do so by preventing future hair loss rather than growing new hair, Christiano said.
Also, Day said, the medications have side effects. "Most of the drugs block hormones or enzymes," she said. "However, they are not specific to the scalp so side effects can include decreased libido as well as potential damage to the liver."
"The medications need to be taken indefinitely in order to remain effective," she said, "and for some people, the medications do not adequately control the hair loss."
A gene-based treatment, by contrast, might allow hair to grow normally. And understanding the genetic basis of baldness could help researchers find better treatments for other conditions, such as alopecia, which causes hair loss, Christiano said, adding that she has alopecia.