Abstract
Erythropoietic protoporphyria may develop with chromosome 18 long arm segmental deletions. To the best of our knowledge, this is the second case wherein the deletions include the ferrochelatase (FECH) gene (18q21.3). Herein, we describe the case of a 15-year-old boy with a mosaic chromosome 18q21.2-q22.1 deletion. He showed elevated levels of erythrocyte protoporphyrin and tested positive for photohemolysis leading to the diagnosis of erythropoietic protoporphyria. Array comparative genomic hybridization analysis revealed deletion of chromosome 18 long arm 21.2-22.1. Loci for the FECH gene (18q21.3), and transcription factor 4 (TCF4), deletion of which causes Pitt-Hopkins syndrome, were found at the same site. Erythropoietic protoporphyria was diagnosed genetically by an NM_000140.5 (FECH): c.315-48 T>C (rs2272783) polymorphism detected through direct sequencing of the FECH gene. The mean age of onset of photosensitivity symptoms in erythropoietic protoporphyria is four years. However, the patient did not develop erythropoietic protoporphyria until 15 years of age, which may have been due to minimal sun exposure and mosaic chromosome 18q21.2-q22.1 deletion.
