Question: What is (are) Erythropoietic protoporphyria ?
Answer: Erythropoietic protoporphyria is a type of porphyria. Porphyrias are caused by an abnormality in the heme production process. Heme is essential in enabling our blood cells to carry oxygen and in breaking down chemical compounds in the liver. Erythropoietic protoporphyria is caused by impaired activity of ferrocheletase (FECH), an important enzyme in heme production. This results in the build-up of protoporphyrin in the bone marrow, red blood cells, blood plasma, skin, and eventually liver. Build up of protoporphyrin can cause extreme sensitivity to sunlight, liver damage, abdominal pain, gallstones, and enlargement of the spleen.
Source: GARD

Question: Is Erythropoietic protoporphyria inherited ?
Answer: How is erythropoietic protoporphyria (EPP) inherited? EPP is inherited in an autosomal recessive manner. In most cases, affected individuals have one severe (loss-of-function) mutation that is inherited from one parent, and another weak (low-expression) mutation that is inherited from the other parent. In a small number of cases, an affected individual has two loss-of-function mutations. When 2 carriers of an autosomal recessive condition have children, each child has a: 25% (1 in 4) chance to be affected 50% (1 in 2) chance to be an unaffected carrier like each parent 25% (1 in 4) chance to be unaffected and not be a carrier
Source: GARD