RESUMO
We measured the activity of the enzyme porphobilinogen deaminase in red blood cells of 222 persons. Ninety-seven of 107 patients with acute intermittent porphyria had enzyme activity below the normal range, whereas 55 of 56 patients with other types of porphyria had normal activity. This underscores the utility of this test in confirming the diagnosis of acute intermittent porphyria. Measurement of enzyme activity in 41 families with acute intermittent porphyria demonstrated that deficient activity is inherited as an autosomal dominant trait. Many latent carriers of the genetic defect were identified by family studies, permitting appropriate precautions to avoid potentially lethal porphyric attacks.
Assuntos
Amônia-Liases/sangue , Ensaios Enzimáticos Clínicos , Eritrócitos/enzimologia , Hidroximetilbilano Sintase/sangue , Porfirias/diagnóstico , Doença Aguda , Triagem de Portadores Genéticos , Humanos , Hidroximetilbilano Sintase/genética , Porfirias/genéticaRESUMO
An elderly woman was found to have hepatocellular carcinoma and, incidental to this, markedly elevated levels of porphobilinogen in urine and serum. The delta-aminolevulinic acid levels in urine and serum were normal, but there was a distinct increase of porphyrins in urine and feces. Neither the patient nor her family gave a history suggestive of a clinical porphyria. The patient died from the carcinoma without ever exhibiting porphyric symptoms. It is assumed that the hepatocellular carcinoma produced the excessive amounts of porphobilinogen.
Assuntos
Neoplasias Abdominais/complicações , Carcinoma Hepatocelular/complicações , Porfirias/etiologia , Idoso , Fezes/análise , Feminino , Humanos , Neoplasias Hepáticas , Porfobilinogênio/metabolismo , Porfobilinogênio/urina , Porfirinas/análise , Porfirinas/biossíntese , alfa-Fetoproteínas/análiseRESUMO
A porphyria kindred in which the index case has porphyria variegata had also been shown to include a case of porphyria cutanea tarda, typical both from chemical and clinical features. The possibility that this was purely acquired rather than genetic seemed unlikely, but could not be wholly excluded. Recently, a niece of both of these cases, although asymptomatic, has been found to conform chemically with porphyria cutanea tarda, including the excretion of the isocoproporphyrin series, and thus represents the second case of this form of porphyria in this family. This strengthens the concept of genetic heterogeneity in this kindred and supports the suggestion of a double heterozygosity, as proposed in the primary paper [Watson, C.J. et al. (1975) Proc. Nat. Acad. Sci. USA 72, 5126-5129].
Assuntos
Porfirias/genética , Heterozigoto , Humanos , LinhagemRESUMO
A woman aged 54 was studied because of a severe acute porphyric (neurologic) relapse with clinical and chemical findings characteristic of porphyria variegata. During a family survey, her brother, aged 59, was found to have chemical abnormalities typical of porphyria cutanea tarda, without suggestion of neurologic manifestations. He had mild skin changes compatible with either of these forms of porphyria. The sister exhibited the protocoproporphyria of porphyria variegata, together with a large amount of fecal "x" porphyrin fraction, without demonstrable isocoproporphyrins. The brother had a uro-isocopro-type of porphyria in accord with the diagnosis of porphyria cutanea tarda, and quite at variance with the sister's findings. This occurrence of porphyria variegata and porphyria cutanea tarda in siblings is thus far unique. Certain hypotheses are considered in respect to genetic aspects of the differing prophyrias in this sibling pair.
Assuntos
Porfirias/genética , Doença Aguda , Adulto , Coproporfirinogênios/metabolismo , Fezes/análise , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Porfirias/metabolismo , Uroporfirinas/metabolismoAssuntos
Heme/metabolismo , Porfirinas/metabolismo , Ácido Aminolevulínico/metabolismo , Anemia Hemolítica/sangue , Antimetabólitos/farmacologia , Bilirrubina/metabolismo , Radioisótopos de Carbono , Eritrócitos/metabolismo , Fezes/análise , Glicina/metabolismo , Hematócrito , Hemoglobinas/biossíntese , Humanos , Ferro/metabolismo , Radioisótopos de Ferro , Marcação por Isótopo , Icterícia/sangue , Métodos , Isótopos de Nitrogênio , Fagocitose , Fenil-Hidrazinas/farmacologia , Porfirias/sangue , Porfirinas/sangue , Reticulócitos/metabolismo , Fatores de Tempo , TrítioRESUMO
The rat hemidiaphragm was studied in vitro as a test system to evaluate the effects of heme precursors and the uroporphyrins upon neuromuscular excitability. Porphobilinogen and porphobilin had no effect on the resting miniature end-plate potential frequency, but the K(+)-augmented frequency was significantly reduced. Porphobilin and porphobilinogen gave 50% of their maximal effect at concentrations of 0.008 and 0.6 mug/ml, respectively; the effect increased with concentration. Uroporphyrin I at 0.05-1.0 mug/ml caused a 25% decrease in frequency, but the effect did not increase with concentration. At similar concentrations, uroporphyrin III was without effect. The concentrations of porphobilin and porphobilinogen effective in inhibiting the K(+) stimulation, which are several orders of magnitude lower than the effective concentrations of simple amino acids, are those which might reasonably be expected in the sera of patients with acute intermittent porphyria.