Operating room docs, for example, have long reported that redheads appear to need more anesthetic than others. The new study suggests that that observation is an accurate one — mostly. Those with the MC1R mutation are more sensitive to opiate pain killers — which means they’d actually need less — but less sensitive to other types, most notably lidocaine injections. One study which used heat-related pain as its litmus of overall sensitivity showed that redheads indeed felt things more acutely and unpleasantly, probably because the MC1R mutation releases a hormone that stimulates a brain receptor associated with pain regulation. (More on Time.com: Study: Researchers Identify Hundreds of Gene Variants That Contribute to Height)
Redheads are also said — anecdotally at least — to be more susceptible to hernias. The study did not establish that conclusively, but it did find a tangential link between chromosome 16 and a condition called brittle cornea syndrome, the sufferers of which have a slightly elevated hernia risk.