Ged et al. (2004) described a novel mutation of the uroporphyrinogen III synthase (UROS) gene responsible for severe cutaneous lesions and UROS enzymatic deficiency in a large kindred. The members of the kindred were belonging to the Palestinian Muslim community. The parents were non consanguineous, but originated from the same village. Two male and two female sibs showed the symptoms of congenital erythropoietic protoporphyria (CEP) during infancy. Another brother was severely affected and showed massive multilations and deformities due to bone resorption on his hands. Of these five affected sibs, four of them were analyzed revealing massive uroporphyrinuria, barely detectable activity of the enzyme UROS, and homozygosity for a new mutation of the UROS gene (substitution of serine by praline at position 47, S47P). The mother and one of her sons were heterozygous carriers, and another son was healthy non carrier. The mother was heterozygous for the sickle cell trait. Surprising findings were observed in a sister who had neither cutaneous lesions nor hematological signs. She had also moderate uroporphyrinuria, and presented the mutation (S47P) at the homozygous state with profound deficiency of UROS activity. Ged et al. (2004) proposed that she was protected from the accumulation of porphyrins which might be attributed to the non-hyperactive porphyrin biosynthesis. However, her hemoglobin electrophoresis was normal which ruled out the hypothesis that certain hematological disorders could limit porphyrin synthesis. Another hypothesis that could be related to her case was the influence of a modifier gene. Moreover, the unusual condition of the sister could be associated with the deregulation of the delta-aminolevulinate synthase II (ALAS2) gene, which was related to both iron and heme homeostasis.