RECESSIVE GENE OF REDHEADS - more prone to cancer, parkinsons, tourette's, endometriosis

"Compared to blondes or brunettes, redheads are more than twice as likely to avoid going to the dentist—and they may have good reason. The same genetic variant that explains their fiery locks also makes redheads resistant to local anesthesia, such as Novocaine, explaining their dread of dental procedures, University of Louisville researchers reported in Journal of the American Dental Association.
In fact, redheads may need 20 percent more anesthesia, researchers from the same center reported in an earlier study, in which women with bright red hair were compared to those with dark tresses. And those with ruby locks are also more sensitive to heat and cold than the rest of us, researchers report. Here’s a look at other surprising findings about redheads.
Higher risk for skin cancer—even if they shun the sun 
Fair skin that provides less natural protection from the sun isn’t the only reason redheads are three times more susceptible to skin cancer than people with other hair colors. A new animal study published in Nature shows that the pigment responsible for their distinctive coloring also plays a role in their risk for melanoma, the deadliest form of skin cancer.
The researchers were planning to study the effects of UV radiation on mice bred to mimic olive-skinned, ginger, and albino coloring, but were shocked when half of the ginger mice developed melanoma before being exposed to UV rays. According to researcher David Fisher, “There is something about the redhead genetic background that is behaving in a carcinogenic fashion, independent of UV,” suggesting that slathering on sunscreen or avoiding the sun may not be enough protection.
The study suggests that redheads should be extra diligent about checking their skin for suspicious spots and being screened for skin cancer, which is highly treatable if caught early. The researchers emphasize that the risk associated with red pigment is almost certainly a less common trigger than sun exposure, since only 20 percent of these cancers develop in areas that are normally covered by a swimsuit.
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Higher Risk for Other Diseases
Other disorders that disproportionately affect redheads include:

Parkinson’s disease.  A Harvard study reports that redheads have a nearly 90 percent-increased risk for the progressive neurological disorder that affects balance and coordination. However, another recent study suggests that taking folic acid may be protective. 
Endometriosis.  Another Harvard study involving more than 90,000 women linked red hair to a 30 percent higher risk for this painful gynecological disorder in which tissue similar to the lining of the uterus grows elsewhere in the pelvis. However, the study found that red hair only ups the threat in fertile women, while lowering it in infertile women, compared to those with any other hair color. 
Tourette’s syndrome. An Australian study reported that not only is there a nearly seven-fold higher rate of neuropsychiatric disorder characterized by motor and verbal tics in redheads, but 55 percent of the Tourette’s patients studied had also relatives with ruby hair. The researchers theorize that a gene for the tic disorder may be located near the ginger gene.

Stronger Bones, Immune System
Some biologists believe that the reason there are more redheads in cold, cloudy climes, such as Scotland, is that the pale skin that typically accompanies a fiery mane allows the body to soak more vitamin D. Not only does D help protect against many diseases, but it’s essential for healthy bones—and helps ward off osteoporosis, the brittle-bone disease that leads to fractures. 
At a recent seminar on hair color and health, Scottish researcher Jonathan Rees reported that throughout history the “ginger gene” may have “played a big role” in protecting many redheads from rickets (soft, weak bones triggered by vitamin D deficiency). He added that, “there’s also good data that we need vitamin D to fight against infections like tuberculosis,” the world’s most common contagious disease.
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Redheads don't go gray
Unlike blondes and brunettes, redheads never develop gray hair as they age. A little-known fact about natural red hair is that it retains its original color longer than any other hair hue. Eventually, the ginger tends to turn blond, and ultimately white. On average, redheads have thicker hair, but fewer strands (about 90,000), compared to blondes (110,000) or brunettes (140,000).
And they're not becoming extinct
Although redheads have been around since the Neanderthal days, a few years ago many news reports claimed that by 2060 they’d be extinct. This myth was spawned by the notion that recessive genes—such as red hair—inevitably die out. Actually, even if all redheads stopped having kids, there’s no shortage of non-redheads who carry “ginger genes” to pass the trait on. In fact, scientists reported in December that 40 percent of Britons carry recessive genes for red hair, based on DNA analysis of saliva samples from 5,000 people.
The world’s highest rate of redheads is found in Scotland, where an estimated 13 percent of Scots—about 650,000 people—have flame-colored tresses, compared to 4 percent of Europeans and less than 2 percent of the global population, according to STV News. In the US, there are an estimated 6 million redheads."