RESUMO
Acute intermittent porphyria (AIP) caused by mutations in the hydroxymethylbilane synthase gene (HMBS), has been reported in almost all human populations, with varying frequencies. A founder effect for a few specific mutations in geographic regions where prevalence is high (Sweden, The Netherlands, Switzerland) has been established through haplotype analyses, while some other mutations (R26H, R26C) have been repeatedly reported in many populations with different genetic backgrounds. Epidemiological, biochemical and molecular data on AIP in Venezuela were gathered during the last two decades; 24 independent families with AIP were ascertained, based on a deficient HMBS activity and increased porphobilinogen (PBG) urinary excretion. Molecular analyses of coding and splicing regions were performed in 23 families, to establish disease-causing changes, and haplotype analyses were used to assess ancestral kinships between them. Changes were detected in 16 out of 23 families, 9 of them being different: R26H, R26C, c.87+5G>A, c.267-54_61delgaaggggt, R116W, Q180X, c.825+1G>A, c.913-1delG, and 3' UTR *277G>A. Seven mutations were found, each one in a single family; one mutation was present in two unrelated families, whereas mutation Q180X was shared by 7 independent kindreds, all of which had the same haplotype (-);T;A;T;G;T;A;G (3167delG; 3530T>C; 3581A>G; 3982T>C; 6479G>T; 7052T>C; 7064A>C; 7779G>A). Six out of seven different Q180X carrier families came from the same geographic focus (Santa Lucía, Miranda State). Dense geographic aggregation with one identical haplotype strongly suggests a remote founder phenomenon for these Venezuelan AIP families, carrying an unreported but most frequent mutation.
Assuntos
Hidroximetilbilano Sintase/genética , Mutação , Polimorfismo de Nucleotídeo Único , Porfiria Aguda Intermitente/genética , Adolescente , Adulto , Biomarcadores/urina , Criança , Pré-Escolar , Análise Mutacional de DNA , Feminino , Efeito Fundador , Frequência do Gene , Predisposição Genética para Doença , Haplótipos , Hereditariedade , Heterozigoto , Humanos , Hidroximetilbilano Sintase/metabolismo , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Porfobilinogênio/urina , Porfiria Aguda Intermitente/diagnóstico , Porfiria Aguda Intermitente/enzimologia , Porfiria Aguda Intermitente/epidemiologia , Prevalência , Fatores de Tempo , Venezuela/epidemiologia , Adulto JovemRESUMO
Acute hepatic porphyrias are human metabolic diseases characterized by the accumulation of heme precursors, such as 5-aminolevulinic acid (ALA). The administration of glucose can prevent the symptomatology of these diseases. The aim of this work was to study the relationship between glucose metabolism disturbances and the development of experimental acute hepatic porphyria, as well as the role of reactive oxygen species (ROS) through assays on hepatic key gluconeogenic and glycogenolytic enzymes; phosphoenolpyruvate carboxykinase (PEPCK) and glycogen phosphorylase (GP), respectively. Female Wistar rats were treated with three different doses of the porphyrinogenic drug 2-allyl-2-isopropylacetamide (AIA) and with a single dose of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). Thus, rats were divided into the following groups: group L (100 mg AIA + 50 mg DDC/kg body wt.); group M (250 mg AIA + 50 mg DDC/kg body wt.) and group H (500 mg AIA + 50 mg DDC/kg body wt.). The control group (group C) only received vehicles (saline solution and corn oil). Acute hepatic porphyria markers ALA-synthase (ALA-S) and ferrochelatase, heme precursors ALA and porphobilinogen (PBG), and oxidative stress markers superoxide dismutase (SOD) and catalase (CAT) were also measured in hepatic tissue. On the other hand, hepatic cytosolic protein carbonyl content, lipid peroxidation and urinary chemiluminescence were determined as in vivo oxidative damage markers. All these parameters were studied in relation to the different doses of AIA/DDC. Results showed that enzymes were affected in a drug-dose-dependent way. PEPCK activity decreased about 30% in group H with respect to groups C and L, whereas GP activity decreased 53 and 38% in group H when compared to groups C and L, respectively. On the other hand, cytosolic protein carbonyl content increased three-fold in group H with respect to group C. A marked increase in urinary chemiluminescence and a definite increase in lipid peroxidation were also detected. The activity of liver antioxidant enzyme SOD showed an induction of about 235% in group H when compared to group C, whereas CAT activity diminished due to heme depletion caused by both drugs. Based on these results, we can speculate that the alterations observed in glucose metabolism enzymes could be partly related to the damage caused by ROS on their enzymatic protein structures, suggesting that they could be also linked to the beneficial role of glucose administration in acute hepatic porphyria cases.
Assuntos
Glucose/metabolismo , Fígado/enzimologia , Porfiria Aguda Intermitente/enzimologia , Espécies Reativas de Oxigênio/metabolismo , Alilisopropilacetamida/toxicidade , Animais , Dicarbetoxi-Di-Hidrocolidina/toxicidade , Modelos Animais de Doenças , Feminino , Heme/biossíntese , Peroxidação de Lipídeos , Fígado/metabolismo , Medições Luminescentes , Porfiria Aguda Intermitente/induzido quimicamente , Porfiria Aguda Intermitente/metabolismo , Ratos , Ratos Wistar , Urina/químicaAssuntos
Hidroximetilbilano Sintase/genética , Porfiria Aguda Intermitente , Porfiria Aguda Intermitente/diagnóstico , Adolescente , Adulto , Idoso , Feminino , Genes Dominantes , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase , Porfiria Aguda Intermitente/enzimologia , Porfiria Aguda Intermitente/etiologia , Porfiria Aguda Intermitente/genética , Porfiria Aguda Intermitente/patologiaRESUMO
BACKGROUND: Acute intermittent porphyria is a hereditary error of porphyrin metabolism in which the main metabolic defect is caused by a decrease in porphobilinogen deaminase activity. Previous work has demonstrated a higher prevalence of acute intermittent porphyria in the psychiatric patient population than in the general population. The goal of this study was evaluate 300 psychiatric patients and 150 control subjects to detect acute intermittent porphyria by measurement of porphobilinogen (PBG) deaminase activity in blood. METHODS: Screening for porphobilinogen deaminase activity was carried out by fluorometric measurement of porphyrins synthesized during 1 h in blood and the measurement of delta-aminolevulinic acid and porphobilinogen in urine. RESULTS: We found two psychiatric patients, one male and one female, with decreased porphobilinogen deaminase activity. When the families of these patients were studied, one brother was found to have an abnormality. Among controls, a woman was found to have the abnormality and her father was found to have typical features of the disease. CONCLUSIONS: These results indicate a prevalence of porphyria in Mexican psychiatric patients similar to controls, and that measurement of PBG deaminase activity is a good tool for defining acute intermittent porphyria carriers.
Assuntos
Depressão/complicações , Transtornos da Personalidade/complicações , Porfiria Aguda Intermitente/epidemiologia , Esquizofrenia Paranoide/complicações , Doença Aguda , Adolescente , Adulto , Idoso , Alcoolismo/sangue , Alcoolismo/complicações , Alcoolismo/enzimologia , Transtorno da Personalidade Borderline/sangue , Transtorno da Personalidade Borderline/complicações , Transtorno da Personalidade Borderline/enzimologia , Depressão/sangue , Depressão/enzimologia , Feminino , Humanos , Hidroximetilbilano Sintase/sangue , Masculino , México/epidemiologia , Pessoa de Meia-Idade , Linhagem , Transtornos da Personalidade/sangue , Transtornos da Personalidade/enzimologia , Porfiria Aguda Intermitente/sangue , Porfiria Aguda Intermitente/complicações , Porfiria Aguda Intermitente/enzimologia , Prevalência , Esquizofrenia Paranoide/sangue , Esquizofrenia Paranoide/enzimologia , Tentativa de SuicídioRESUMO
A partial deficiency of Porphobilinogen deaminase (PBGD) is responsible for acute intermittent porphyria (AIP). AIP is inherited in an autosomal dominant fashion, and the prevalence in the Argentinean population is about 1:125,000. Here, two new mutations and two previously reported were found in the PBGD gene in 22 Argentinean AIP patients corresponding to 8 different families. To screen for AIP mutations in symptomatic patients, genomic DNA isolated was amplified in 6 PCR reactions, then all coding exons and flanking intronic regions were sequenced. The novel mutations are 841-843delGGA in exon 14, which results in the loss of glycine-281 (G281del), and one 104C>T point mutation in the exon 4 (T35M). To further characterize both novel mutations, the pKK-PBGD construct for the mutant alleles were expressed in E. coli, the enzymatic activity of the recombinant proteins were 1% and 4% of the mean level expressed by the normal allele for 841-843delGGA and T35M, respectively. Hum Mutat 16:373, 2000.
Assuntos
Hidroximetilbilano Sintase/genética , Mutação de Sentido Incorreto/genética , Porfiria Aguda Intermitente/enzimologia , Porfiria Aguda Intermitente/genética , Deleção de Sequência/genética , Adolescente , Adulto , Criança , Feminino , Humanos , Masculino , Metionina/genética , Pessoa de Meia-Idade , Treonina/genéticaRESUMO
Acute intermittent porphyria (AIP), the most common hepatic porphyria, results from the half-normal activity of hydroxymethylbilane synthase (HMB-synthase; EC 4.3.1.8), the third enzyme in the heme biosynthetic pathway. Because life-threatening acute neurologic attacks of this autosomal dominant disease are triggered by various ecogenic factors (e.g., certain drugs, hormones, alcohol, and starvation), efforts have been directed to identify and counsel presymptomatic heterozygotes in affected families to avoid the precipitating factors. Thus, to determine the nature of the mutations causing AIP in 26 unrelated enzyme-confirmed patients from Argentina, a long-range polymerase chain reaction method was developed to amplify the entire 10-kb gene in two fragments for efficient cycle sequencing and mutation detection. Eight new mutations were identified including two missense mutations (Q34P and G335S), four small deletions (728delCT, 815delAGGA, 948delA, and 985del12), a single base insertion (666insA), and a splice site mutation (IVS12(+1)). In addition, five previously reported mutations (G111R, R173W, Q204X, R201W, and 913insC) were detected. Notably, G111R was identified in 12 of the 26 (46%) presumably unrelated propositi; however, haplotype analysis with intragenic and flanking markers indicated an ancestral founder. Expression of the two new missense mutations (Q34P and G335S) in f1 E. coli resulted in 2.5% or less of the normal expressed enzyme, confirming their defective function. Thus, eight new and five previously reported HMB-synthase mutations, including a common lesion, were detected, permitting accurate identification and counseling of presymptomatic carriers in these 26 unrelated Argentinean AIP families with this dominant porphyria.
Assuntos
Hidroximetilbilano Sintase/genética , Mutação Puntual , Porfiria Aguda Intermitente/enzimologia , Porfiria Aguda Intermitente/genética , Adolescente , Adulto , Argentina , Sequência de Bases , Criança , Análise Mutacional de DNA , Primers do DNA/genética , Escherichia coli/genética , Feminino , Efeito Fundador , Genes Dominantes , Aconselhamento Genético , Haplótipos , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Reação em Cadeia da Polimerase/métodos , Polimorfismo GenéticoRESUMO
A frequent coexistence of diabetes and porphyria disease has been reported. Under normal conditions, porphyrin biosynthesis is well regulated to only form the amount of heme required for the synthesis of the various hemoproteins. The activity of some heme enzymes and rhodanese in streptozotocin (STZ) induced diabetic mice and in allylisopropylacetamide (AIA) induced experimental acute porphyria mice has been examined. The role of alpha-tocopherol (alpha-T), reported to prevent protein glycation in vitro, has also been investigated. AIA induced hepatic delta-aminolevulinic acid synthetase (ALA-S) activity in control animals but was ineffective in the diabetic group. alpha-Tocopherol did not modify ALA-S activity in either group. delta-Aminolevulinic acid dehydratase (ALA-D) and deaminase activities were significantly diminished both in liver and blood of diabetic animals. alpha-Tocopherol prevented inhibition of ALA-D, deaminase and blood rhodanese activities in diabetic animals but alpha-tocopherol by itself did not affect the basal levels of the enzymes studied. The potential use of alpha-tocopherol to prevent late complications of diabetes, including the onset of a porphyria like syndrome is considered.