Porphyria

http://en.wikipedia.org/wiki/Porphyria

Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway (also called porphyrin pathway). They are broadly classified as acute (hepatic) porphyrias and cutaneous (erythropoietic) porphyrias, based on the site of the overproduction and accumulation of the porphyrins (or their chemical precursors). They manifest with either neurological complications or skin problems (or occasionally both). A clinically induced and histologically identical condition is called pseudoporphyria. Pseudoporphyria is characterized by normal serum and urine porphyrin levels. The prevalence of all types of porphyria taken together has been estimated to be approximately 1 in 25,000 in the United States.[4] The worldwide prevalence has been estimated to be somewhere between 1 in 500 to 1 in 50,000 people.

Congenital Erythropoietic porphyria (Gunther disease)

rs28941774 (variant absent for GG)
rs28941775 (variant absent for TT)

Variegate porphyria

rs12735723 (variant absent for CC)
rs28936676 (variant absent for AA)
rs28936677 (variant absent for TT)

Also