INTRODUCTION.
Harderoporphyria is a disorder of heme biosynthesis, inherited in an autosomal recessive manner caused by specific mutations in the coproporphyrinogen oxidase (CPOX) gene. Mutations in CPOX gene (Enzyme Commission number EC# 1.3.3.3) usually cause hereditary coproporphyria, an acute hepatic porphyria.
There is evidence that harderoporphyria (HARPO) is caused by homozygous or compound heterozygous mutation in the (CPOX) gene on cytogenetic location 3q11.2 and genomic coordinates 3:98,570,488-98,593,611. The screenshot of the coproporphyrinogen oxidase (CPOX) gene 23,124 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides CPOX in the 3q11.2 cytogenetic location are listed BENEATH.
| Coordinate | Symbol | Genomic Name |
| 3:97,941,818 | RIOX2 | Ribosomal oxygenase 2 |
| 3:97,985,102 | GABRR3 | Gamma-aminobutyric acid receptor, RHO-3 |
| 3:98,515,483 | CLDND1 | Claudin domain-containing protein 1 |
| 3:98,531,978 | GPR15 | G protein-coupled receptor-15 |
| 3:98,570,488 | CPOX | Coproporphyrinogen oxidase |
| 3:98,732,262 | ST3GAL6 | ST3 beta-galactoside alpha-2,3-sialyltransferase 6 |
| 3:98,795,941 | DCBLD2 | Discoidin, CUB, and LCCL domain protein 2 |
| 3:99,638,594 | COL8A1 | Collagen VIII, alpha-1 polypeptide |
| 3:99,828,811 | FILIP1L | Filamin A-interacting protein 1-like |
| 3:100,185,824 | TMEM30C | Transmembrane protein 30C |
