Seven Novel Mutations in Bulgarian Patients with Acute Hepatic Porphyrias (AHP)

Abstract

Acute intermittent porphyria (AIP), variegate porphyria (VP), and hereditary coproporphyria (HCP) are caused by mutations in the hydroxymethylbilane synthase (HMBS), protoporphyrinogen oxidase (PPOX), and coproporphyrinogen oxidase (CPOX) genes, respectively. This study aimed to identify mutations in seven Bulgarian families with AIP, six with VP, and one with HCP. A total of 33 subjects, both symptomatic (n = 21) and asymptomatic (n = 12), were included in this study. The identification of mutations was performed by direct sequencing of all the coding exons of the corresponding enzymes in the probands. The available relatives were screened for the possible mutations. A total of six different mutations in HMBS were detected in all seven families with AIP, three of which were previously described: c.76C>T [p.R26C] in exon 3, c.287C>T [p.S96F] in exon 7, and c.445C>T [p.R149X] in exon 9. The following three novel HMBS mutations were found: c.345-2A>C in intron 7-8, c.279-280insAT in exon 7, and c.887delC in exon 15. A total of three different novel mutations were identified in the PPOX gene in the VP families: c.441-442delCA in exon 5, c.917T>C [p.L306P] in exon 9, and c.1252T>C [p.C418R] in exon 12. A novel nonsense mutation, c.364G>T [p.E122X], in exon 1 of the CPOX gene was identified in the HCP family. This study, which identified mutations in Bulgarian families with AHP for the first time, established seven novel mutation sites. Seven latent carriers were also diagnosed and, therefore, were able to receive crucial counseling to prevent attacks.