David Fisher and his team at Massachusetts General Hospital did an experiment on mice with either red or black hair to see how they responded to the introduction of a gene linked with melanoma. They wanted to know more about melanoma after exposure to UV light; focussing on how much it damaged the fair skin of people - or creatures - with red hair.
This was completely unexpected, so they did some new experiments on ginger mice to find out what had actually happened. They bred some hybrid mice that were half-ginger and half-albino and tested them to see if it was the ginger gene or ginger pigment that was the issue. The specially bred mice had the ginger gene, but white hair, and they also tested on mice with both the ginger pigment and the ginger hair.
They tested again to see how they were affected by melanoma-inducing UV. All the white-haired mice were fine, despite carrying the MC1R (ginger) gene.
The mice with ginger hair all got cancer.
It's a shame really. Turns out Voldemort isn't the only thing this lot have to worry about...