Most of us have fingerprints, but some people are born with missing fingerprints. Only four families around the world are known to have been born with this disorder – a disease called ‘adermatoglyphia’. Recently dermatologists have found adermatoglyphia in a Swiss family – 9 out of 16 members have no fingerprints – is caused by a smaller version of a gene called SMARCAD1!

Almost every person is born with fingerprints, and everyone’s are unique. In an effort to find the cause of the disease, dermatologist Eli Sprecher sequenced the DNA of 16 members of one family with adermatoglyphia in Switzerland. Seven had normal fingerprints, and the other nine did not. After investigating a number of genes to find evidence of mutation, the researchers came up empty-handed—until a grad student finally found the culprit, a smaller version of a gene called SMARCAD1

The larger SMARCAD1 is expressed throughout the body, but the smaller form acts only on the skin. Sure enough, the nine family members with no fingerprints had mutations in that gene.

Being born without fingerprints doesn’t occur simply because one gene has been turned on or off, Sprecher said. Rather, the mutation causes copies of the SMARCAD1 gene to be unstable.

Full story about missing fingerprints in a Swiss family:

Missing fingerprints in a Swiss family caused by SMARCAD1 gene!

A budding singer from Las Vegas cut her nails for the last time about 18 years ago – resulting in fingernails total nearly 19 feet + 9 inches long! Guinness Records announced a few days ago that Chris Walton will receive a notification in the 2012 edition of the Guinness Book of World Records!

An impression from Chris Walton’s life:

“I never set out to make it into Guinness,” she says. “It just happened. One day I stopped cutting my nails. I liked the way they looked. And they just kept growing.”

An even more impressive Guinness World Record holder for longest nails is Lee Redmond from Salt Lake City. Her fingernails measured a total of 28 feet in 2008, but in 2009 she lost her nails in a car crash.

The story about Chris Walton’s fingernails:

Chris Walton has the longest fingernails!

Wearing your heart on your sleeve is merely an adage, but most people do display their emotions – even if unintentionally – on their faces. Women tend to be better than men at reading other people’s subtle facial cues, especially cues from the eyes. Because of the gender difference in cognitive empathy – the ability to notice and correctly interpret body language – psychobiologistsscientists that study psychology from a biological perspective, or vice versa have hypothesized that testosterone – a sex hormone present in much higher levels in males versus females levels – could play a role in “mind reading” ability, or lack thereof.

A new study in PNASProceedings of the National Academy of Sciences validates this hypothesis by demonstrating that a dose of testosterone can make women lose some of their cognitive empathy. Researchers recruited 16 young women (age 20-25) to participate in their study. The women were given either a testosterone pill or a placebo, and then tested on their ability to assess emotions based on photographs of eyes. The test the women took is called the Adult Eyes Test, and is available for free from the Autism Research Center at the University of Cambridge. Here’s a sample question (formatting is slightly modified):

For the correct answer, click here.

Each woman was tested twice – once with placebo and once with real testosterone (in random order; they didn’t have any idea which was which). 75% of the women performed worse on the “mind reading” test after taking testosterone than after taking a placebo. So to a first approximation, an artificial increase in testosterone levels impaired women’s abilities to interpret facial expressions.

But the results aren’t quite that simple. Some women were less affected by the extra testosterone than others, and the researchers had a hunch that this could relate to their exposure to testosterone in the womb. All fetuses are exposed to testosterone while developing, but to different extents. There is a simple way to qualitatively measure fetal testosterone exposure – this parameter is believed to be correlated to the adult ratio of ring finger length to index finger length (see picture at the top of this post).

Larger ratios of ring finger to index finger lengths correspond to higher fetal testosterone levels. This study showed no difference between the inherent expression-reading ability of women exposed to higher vs. lower doses of testosterone in the womb. However, the women with longer ring fingers (higher fetal testosterone) seemed to be more easily impaired when given a dose of testosterone in pill form.

Thus, this study demonstrated that (1) testosterone administered to women can impair their ability to read facial expressions, and (2) women who experienced more testosterone in the womb are more sensitive to the effects of testosterone administered as adults. Nothing further can be definitively gathered from these results, but they seem to suggest that men’s testosterone levels could be to blame for their increased confusion about what others (especially women!) are thinking/feeling.
PS. A brand new study reported by researchers from Florida has recently (sep 2011) presented proof that fingers have hormonal receptors!
Via: ICanHasScience

The following finger length study presents a likewise effect:

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