Methemoglobinemia, also known as "met-H", is a genetic blood disorder or disease.

Due to an enzyme deficiency, the blood of met-H victims has reduced oxygen-carrying capacity. Instead of being red in colour, the arterial blood of met-H victims is brown. This results in the skin of Caucasian sufferers gaining a bluish cast. Hereditary met-H is caused by a recessive gene. If only one of parent has this gene, the offspring will have normal hued skin, but if they both have the disorder, there a good chance the offspring will have blue-hued skin.

Attacks of methemoglobinemia can be offset by the use of nitrate-containing drugs.

External links

• Article on the Fugates of Appalachia, an extended family of blue-skinned people http://www.straightdope.com/classics/a980724.html