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Am J Hum Genet. 2008 Sep;83(3):408-14. doi: 10.1016/j.ajhg.2008.08.003. Epub 2008 Sep 4.

C-terminal deletions in the ALAS2 gene lead to gain of function and cause X-linked dominant protoporphyria without anemia or iron overload.

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  • 1Department of Medical Biochemistry and Immunology, University Hospital of Wales and, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.

Abstract

All reported mutations in ALAS2, which encodes the rate-regulating enzyme of erythroid heme biosynthesis, cause X-linked sideroblastic anemia. We describe eight families with ALAS2 deletions, either c.1706-1709 delAGTG (p.E569GfsX24) or c.1699-1700 delAT (p.M567EfsX2), resulting in frameshifts that lead to replacement or deletion of the 19-20 C-terminal residues of the enzyme. Prokaryotic expression studies show that both mutations markedly increase ALAS2 activity. These gain-of-function mutations cause a previously unrecognized form of porphyria, X-linked dominant protoporphyria, characterized biochemically by a high proportion of zinc-protoporphyrin in erythrocytes, in which a mismatch between protoporphyrin production and the heme requirement of differentiating erythroid cells leads to overproduction of protoporphyrin in amounts sufficient to cause photosensitivity and liver disease.

PMID:
18760763
[PubMed - indexed for MEDLINE]
PMCID:
PMC2556430
Free PMC Article

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