In the 1820s there lived a couple in Kentucky whose family would become known as the Blue Fugates. Why? Because they carried a rare genetic condition that gave several members of the family blue skin.
Yes, really.
What caused the Blue Fugates’ blue skin?
The highly unusual condition is known as methemoglobinemia. It’s characterized by elevated levels of a form of hemoglobin called methemoglobin, which has iron in the ferric state rather than the ferrous state – a crucial difference that prevents oxygen from binding to it.
Most of us have a very small amount of methemoglobin in the blood as our bodies have mechanisms for converting it back into normal, oxygen-carrying hemoglobin. However, in rare cases these mechanisms are disrupted, causing the levels of methemoglobin to rise and leading to methemoglobinemia.
Methemoglobinemia is when levels of methemoglobin are unusually high. The symptoms include blue skin, purple lips, and blood that is chocolate brown.
The Blue Fugates Genes
Cases of methemoglobinemia are more commonly acquired, meaning the condition developed as a consequence of exposure to certain chemicals or drugs – but in rare cases, it can be inherited. This was the case for the Blue Fugates, who had not one but two parents who carried the rare genetic trait.
Martin Fugate moved to Troublesome Creek, Kentucky, around 1820. He married and had children with Elizabeth Smith, who was said to be pale “as the mountain laurel that blooms every spring around the creek hollows,” and he was blue.
Curiously, four of their seven children followed in Martin’s shoes in developing blue-hued skin. It’s thought this is because Elizabeth carried a recessive version of the rare genetic disorder, so that even though she herself didn’t have blue skin, she – along with Martin – was still able to pass it on to some of their children.
Were the Blue Fugates otherwise healthy?
Despite their shared condition, most of the Blue Fugates lived well into their 80s and 90s without any severe illness related to their methemoglobinemia. However, in some cases, the condition can be fatal.
Research in the 1960s revealed a possible cause for inherited cases of methemoglobinemia as it found cases in Alaska were linked to loss of function in an enzyme called cytochrome b5 reductase that’s responsible for reducing methemoglobin into hemoglobin. This specific enzyme deficiency only seems to cause blue skin but spares the carrier the failure to thrive connected to other cases of methemoglobinemia, which could explain why the Blue Fugates were able to live well into their old age despite the curious blue hue of their skin.
Source Link: Blue Fugates: Why Did A Family In Kentucky Have Blue Skin?
