Human protoporphyria is a genetically determined metabolic defect in heme biosynthesis. Partial deficiency in the activity of the enzyme ferrochelatase (FC) in bone marrow erythroid cells results in accumulation of protoporphyrin (PP) in rbc, plasma, liver, and feces. PP causes painful cutaneous photosensitivity and may lead to fatal hepatotoxicity in affected children and adults. Much remains unknown about the natural course of human protoporphyria and about its disease mechanisms in skin, bone marrow, and liver. Continuation of ongoing longitudinal investigations of an established protoporphyria study population with a standardized protocol that has already built a data base for 8 years or longer in the majority of 24 currently participating patients, will further advance current understanding of how this disease evolves in a large number of carefully studied individual patients over many years of time. Individual patients may benefit from early detection of adverse changes in hepatic function. Factors leading to development of fatal hepatotoxicity may be learned from retrospective analysis of the accumulated data base for patients who develop liver dysfunction when compared with the data of the population as a whole. Elucidation of the structure and function of human FC will be advanced by biochemical and immunological methods. Purified FC protein produced by novel chromatographic methods that the investigators have already developed will be used to produce polyclonal and monoclonal antibodies useful for characterization studies of mutant versus normal human FCs proposed herein. Development of such immunological reagents and of oligonucleotide probes constructed according to amino acid sequence information derived from peptides cleaved from purified human FC will enable them, in future years, to propose to clone and express the gene for human FC, to initiate a search for its chromosomal assignment, and to determine the precise nature of the FC mutation responsible for human protoporphyria. In vivo stability of FC in bone marrow will be evaluated first in drug-induced rat erythropoiesis and myelopoiesis models, then in human protoporphyric bone marrow. Clinical and laboratory evaluations of unusual cases of several related forms of porphyria that have already provided new information regarding this group of diseases will be continued. In particular, immunomapping of the microanatomical level of the epidermal-dermal separation in porphyria cutanea tarda will be carried out to target appropriate biomolecular components of the basement membrane zone for further study.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR018549-17
Application #
3154990
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1987-02-01
Project End
1994-06-30
Budget Start
1992-07-01
Budget End
1993-06-30
Support Year
17
Fiscal Year
1992
Total Cost
Indirect Cost
Name
New York Medical College
Department
Type
Schools of Medicine
DUNS #
City
Valhalla
State
NY
Country
United States
Zip Code
10595
Poh-Fitzpatrick, Maureen B; Wang, Xiuhua; Anderson, Karl E et al. (2002) Erythropoietic protoporphyria: altered phenotype after bone marrow transplantation for myelogenous leukemia in a patient heteroallelic for ferrochelatase gene mutations. J Am Acad Dermatol 46:861-6
Frank, J; Jugert, F K; Merk, H F et al. (2001) A spectrum of novel mutations in the protoporphyrinogen oxidase gene in 13 families with variegate porphyria. J Invest Dermatol 116:821-3
Bloomer, J R; Poh-Fitzpatrick, M B (2000) Theodore Woodward Award. Pathogenesis of biochemical abnormalities in protoporphyria. Trans Am Clin Climatol Assoc 111:245-56; discussion 256-7
Wang, X; Yang, L; Kurtz, L et al. (1999) Haplotype analysis of families with erythropoietic protoporphyria and novel mutations of the ferrochelatase gene. J Invest Dermatol 113:87-92
Frank, J; McGrath, J A; Poh-Fitzpatrick, M B et al. (1999) Mutations in the translation initiation codon of the protoporphyrinogen oxidase gene underlie variegate porphyria. Clin Exp Dermatol 24:296-301
Frank, J; Nelson, J; Wang, X et al. (1999) Erythropoietic protoporphyria: identification of novel mutations in the ferrochelatase gene and comparison of biochemical markers versus molecular analysis as diagnostic strategies. J Investig Med 47:278-84
Frank, J; Wang, X; Lam, H M et al. (1998) C73R is a hotspot mutation in the uroporphyrinogen III synthase gene in congenital erythropoietic porphyria. Ann Hum Genet 62:225-30
Bonkovsky, H L; Poh-Fitzpatrick, M; Pimstone, N et al. (1998) Porphyria cutanea tarda, hepatitis C, and HFE gene mutations in North America. Hepatology 27:1661-9
Poh-Fitzpatrick, M B (1998) Clinical features of the porphyrias. Clin Dermatol 16:251-64
Zaider, E; Bickers, D R (1998) Clinical laboratory methods for diagnosis of the porphyrias. Clin Dermatol 16:277-93

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