Acute Intermittent Porphyria in a Man with Dual Enzyme Deficiencies.

Porphyrias are a heterogeneous group of metabolic disorders that result from the altered activity of specific enzymes of the heme biosynthetic pathway and are characterized by accumulation of pathway intermediates. Porphyria cutanea tarda (PCT) is the most common porphyria and is due to deficient activity of uroporphyrinogen decarboxylase (UROD). Acute intermittent porphyria (AIP) is the most common of the acute hepatic porphyrias, caused by decreased activity of hydroxymethylbilane synthase (HMBS). An Argentinean man with a family history of PCT who carried the UROD variant c.10_11insA suffered severe abdominal pain. Biochemical testing was consistent with AIP, and molecular analysis of HMBS revealed a de novo variant: c.344 + 2_ + 5delTAAG. This is one of the few cases of porphyria identified with both UROD and HMBS mutations and the first confirmed case of porphyria with dual enzyme deficiencies in Argentina.

An odd case of heteroallelic acute intermittent porphyria in the Argentinean population.

AIP is an acute liver disorder caused by a deficiency of porphobilinogen deaminase (PBGD) characterized by neuroabdominal symptoms. It is an autosomal dominant disease. However, homozygous dominant AIP (HD-AIP) have been described. In some cases erythrodontia was observed. CEP is an autosomal recessive disease produced by mutations in the uroporphyrinogen III synthase gene (UROS), characterized by severe cutaneous lesions and erythrodontia. The aim of the work was to establish the differential diagnosis of porphyria in a patient with abdominal pain, neurological attacks, skin symptoms and erythrodontia. The PBGD activity was reduced 50% and the genetic analysis indicated the presence of two genetic variants in the PBGD gene, p.G111R and p.E258G, a new genetic variant, revealing a case of heteroallelic HD-AIP. The patient, first diagnosed as a carrier of a dual porphyria: AIP / CEP based on the excretion profile of porphyrins, precursors and her clinical symptoms, would be an atypical case of human HD-AIP. These results would also suggest the presence of a phenocopy of the CEP, induced by an endogenous or exogenous factor. Our findings highlight the importance of genetic studies for a proper diagnosis of porphyria, prevention of its manifestation and its treatment.

Functional associations of genetic variants involved in the clinical manifestation of erythropoietic protoporphyria in the Argentinean population.

BACKGROUND: Combined inheritance of genetic variants in ferrochelatase gene (FECH) are implicated in clinical manifestation of Erythropoietic Protoporphyria (EPP). OBJECTIVE: Identify the genetic variants in FECH gene and their associations in the expression of EPP in Argentina. Determine the allelic frequency of polymorphic variants, associations in cis and its linkage disequilibrium. METHODS: The FECH gene was PCR-amplified and sequenced. Allelic variants of intragenic polymorphisms were identified by PCR followed by sequencing or restriction digestion analysis. Residual FECH activity was determined by prokaryotic expression in Escherichia coli JM109. Data were analyzed using Haploview and Statistix 9. RESULTS: Ten mutations were identified: three novel (p.S222N; p.R298X and p.R367X) and seven already known (g.12490_18067del; p.R115X; p.I186T; c.580_584delTACAG; c.598 + 1 G>T; p.Y209X and p.W310X). The p.R115X mutation was found in two families. The p.S222N mutation expressed 5% of normal activity. Only individuals who inherited a mutation combined in trans to a low expression allele c.1-251G, c.68-23T, and c.315-48C, showed clinical symptoms. The absence of c.315-48C variant was sufficient for not triggering EPP. However, these variants showed high levels of cosegregation and GTC haplotype is over-represented in EPP patients. CONCLUSION: In the dominant inheritance form of EPP, c.315-48C variant in trans to the mutated allele is sufficient to trigger the disease. The presence of GTC haplotype in all patients with dominant EPP could be due to the high level of cosegregation of c.315-48C with c.1-251G and c.68-23T variants in our population.

The very first description of a patient with hepatoerythropoietic porphyria in Argentina. Biochemical and molecular studies.

Hepatoerythropoietic Porphyria (HEP) is the rare homozygous form of Porphyria Cutanea Tarda (PCT). It is characterized clinically by the early onset of severe skin manifestations which can be confused with Congenital Erythropoietic Porphyria (CEP) or with PCT when the symptoms are mild. We describe the case of a 14 year-old child with skin manifestations similar to those observed in PCT. The biochemical assays ruled out a CEP as well as they suggested the development of a HEP. Although his symptoms were not severe enough to be HEP, the enzymatic activity was dramatically reduced to a 5% of normal values and the molecular analysis revealed the presence of two already known different mutations on the patient's URO-D gene, c.703 C>T and IVS9-1. Each parent carry one of the mutations, but they were absent in the brother. This is the first Argentinean HEP case ever described which appeared in a compound heterozygous form and less residual URO-D activity but associated to a mild phenotype.

Porfirias poco frecuentes: Casos detectados en la población argentina / Non frequent porphyrias in the argentinean population

Las porfirias son consecuencia de fallas en el metabolismo del hemo. Se clasifican según el tipo de sintomatología clínica prevalente o el órgano donde se expresa preferencialmente la falla metabólica. En general la deficiencia enzimática está asociada a mutaciones en los genes que codifican para cada una de las enzimas. Están descritos 7 tipos de porfiria diferentes. Se transmiten por carácter autosómico dominante a excepción de la PCE, la PHE y la NPA que son recesivas. Sin embargo, están reportadas variantes homocigotas para el resto de las porfirias de pronóstico y evolución mucho más grave que la forma heterocigota. La descripción de estos casos poco frecuentes, sus tratamientos y evolución, facilitarían tanto el diagnóstico diferencial de la porfiria como el conocimiento de las posibilidades terapéuticas en cada caso. Asimismo para las porfirias heterocigotas con manifestación infantil, su identificación temprana y tratamiento aseguraría una mejor evolución minimizando los riesgos asociados. Se han diagnosticado 5 casos de porfirias agudas en niñas: 2 de PAI, 2 de PV y 1 de CPH. Entre las porfirias cutáneas se presentan 25 casos de PCT infantil, el primer caso de PHE en Argentina, 4 casos de PCE infantil y 1 en un adulto y 2 casos de PPE con compromiso hepatobiliar.

The Porphyrias are a group of diseases resulting from partial deficiencies in one of the heme biosynthetic enzymes. These disorders can be classified on the basis of their clinical manifestations or according the organ where the metabolic deficiency is mainly expressed. In general this enzyme deficiency is associated with mutations in the genes which codify each enzyme. There are 7 types of Porphyrias. They are autosomal dominant disorders with the exception of PCE, PHE and NPA which are recessive. However, some rare and severe cases with recessive inheritance have also been reported. The description of these infrequent cases and their treatments and evolution would make easier the differential diagnosis of Porphyrias as well as the therapeutic possibilities to be applied in each case. Moreover, it is very important the early identification and treatment of infantile heterozygous porphyrias to avoid the risks of associatedd complications. In the CIPYP we have diagnosed 5 cases of infantil Acute Porphyrias: 2 PAI, 2 PV and 1 CPH. In the group of Cutaneous Porphyrias we present 25 cases of infantil PCT, the first case of PHE in Argentina, 4 cases of infantil PCE and 1 adult PCE and 2 cases of PPE with hepatic failure.

Acute porphyrias in the Argentinean population: a review.

The porphyrias are a group of inherited metabolic disorders of heme biosynthesis which result from a partial deficiency in one of its seven specific enzymes, after its first and rate limiting enzyme, delta-aminolevulinic acid synthetase. They can be classified on the basis of their clinical manifestations into cutaneous, acute and mixed disorders. Acute intermittent porphyria (AIP) is the most common type of hepatic acute porphyrias, inherited as an autosomal dominant trait, caused by a defect in the gene which codifies for the heme enzyme porphobilinogen deaminase. Its prevalence in the Argentinean population is about 1:125,000. A partial deficiency in another enzyme, protoporphyrinogen oxidase, produces variegate porphyria (VP), the second acute porphyria most frequent in the Argentinean population (1:600,000). Here, we review all the mutations we have found in 46 AIP and 9 VP unrelated Argentinean patients. To screen for mutations in symptomatic patients, we have proposed a geneticresearch strategy.

Identification and characterization of two novel mutations that produce acute intermittent porphyria: A 3-base deletion (841-843delGGA) and a missense mutation (T35M).

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.

Porfiria variegata: signos cutáneos, agudos y bioquímicos / Primer estudio genético en pacientes Argentinos / Variegate porphyria: cutaneus sign, biochemistry and sharp. Genetic first study in Argentinean patients

Las porfirias son enfermedades metabólicas que surgen como consecuencia de una deficiencia enzimática parcial de alguna de las enzimas del hemo. En la porfiria Variegata (PV) este defecto se encuentra a nivel de la Protoporfirinógeno oxidasa (PPOX) quwe transforma el Protoporfirinógeno IX en Protoporfirina IX. Se caracteriza por presentar el síndromeagudo y cutáneo. Es una patología genéticamente heterogénea, al presente se han detectado 77 mutaciones diferentes en el gen de la PPOX, responsables de esta porfiria. Nuestro objetivo es el estudio bioquímico y molecular de pacientes con sintomatología de PV para llegar a un dignóstico certero de la enfermedad y hacerlo extensivo a sus familiares con el fin de identificar a los portadores asintomáticos y asesorarlos acerca del contacto con los factores desencadenantes de esta porfiria. Hasta el momento el estudio genético nos permitió detectar 2 mutaciones, una mutación puntual recientemente descripta que produce cambio de aminoácido, R168H en el exón 6 y una inserción nueva, 1320InT, que produce corrimiento del marco de lectura. Estos resultados han permitido confirmar el diagnóstico de PV en estos pacientes(AU)

Porfiria variegata: signos cutáneos, agudos y bioquímicos. Primer estudio genético en pacientes Argentinos / Variegate porphyria: cutaneus sign, biochemistry and sharp. Genetic first study in Argentinean patients

Las porfirias son enfermedades metabólicas que surgen como consecuencia de una deficiencia enzimática parcial de alguna de las enzimas del hemo. En la porfiria Variegata (PV) este defecto se encuentra a nivel de la Protoporfirinógeno oxidasa (PPOX) quwe transforma el Protoporfirinógeno IX en Protoporfirina IX. Se caracteriza por presentar el síndromeagudo y cutáneo. Es una patología genéticamente heterogénea, al presente se han detectado 77 mutaciones diferentes en el gen de la PPOX, responsables de esta porfiria. Nuestro objetivo es el estudio bioquímico y molecular de pacientes con sintomatología de PV para llegar a un dignóstico certero de la enfermedad y hacerlo extensivo a sus familiares con el fin de identificar a los portadores asintomáticos y asesorarlos acerca del contacto con los factores desencadenantes de esta porfiria. Hasta el momento el estudio genético nos permitió detectar 2 mutaciones, una mutación puntual recientemente descripta que produce cambio de aminoácido, R168H en el exón 6 y una inserción nueva, 1320InT, que produce corrimiento del marco de lectura. Estos resultados han permitido confirmar el diagnóstico de PV en estos pacientes

Acute intermittent porphyria: biochemical and clinical analysis in the Argentinean population.

Acute intermittent porphyria (AIP) is the most common type of hepatic acute porphyria. In this work, we have analyzed the biochemical data of all Argentinean AIP families studied in the Porphyrins and Porphyrias Research Centre (CIPYP). We have shown that: (i) the prevalence for this population is about 1:125,000; (ii) the disease is more frequent in women than in men (7:3); (iii) about 60% are latent carriers; (iv) 15% of patients with symptomatic AIP died during an acute attack; (v) the most important precipitating factors of acute attacks in our population were the ingestion of therapeutic drugs (25%), anesthetics in surgical interventions (25%) and infections (20%); (vi) the initial symptom in Argentinean AIP individuals is severe abdominal pain (100%), and it is often accompanied by constipation (37%), anorexia (37%) and tachycardia (30%); and (vii) the percentage of recurrence of the acute attacks is high (81%).

Identification and characterization of hydroxymethylbilane synthase mutations causing acute intermittent porphyria: evidence for an ancestral founder of the common G111R mutation.

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.

Acute intermittent porphyria: characterization of two novel mutations in the porphobilinogen deaminase gene, one amino acid deletion (453-455delAGC) and one splicing aceptor site mutation (IVS8-1G>T).

A partial deficiency of Porphobilinogen deaminase (PBG-D) 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 three previously reported were found in the PBG-D gene in 12 Argentinean AIP patients corresponding to 5 different families. To screen for AIP mutations in symptomatic patients, genomic DNA isolated was amplified in 2 Multiplex PCR reactions, then all coding exons and flanking intronic regions were sequenced. The new mutations are 453-455delAGC in exon 9 which results in the loss of an alanine residue at position 152, and one new point mutation in the splicing aceptor site in the last position of intron 8 (IVS8-1G>T) which leds to a 15 bp deletion because a cryptic site (first AG upstream) is used. Both mutations produce amino acid deletion without frameshift effect. To further characterize the 453-455delAGC mutation, the pKK-PBGD construct for the mutant allele was expressed in E. coli, the enzymatic activity of the recombinant protein was 1.3% of the mean level expressed by the normal allele. Finally, three missense mutations, previously reported, were identified in three unrelated families.

Familial porphyria cutanea tarda: characterization of seven novel uroporphyrinogen decarboxylase mutations and frequency of common hemochromatosis alleles.

Familial porphyria cutanea tarda (f-PCT) results from the half-normal activity of uroporphyrinogen decarboxylase (URO-D). Heterozygotes for this autosomal dominant trait are predisposed to photosensitive cutaneous lesions by various ecogenic factors, including iron overload and alcohol abuse. The 3.6-kb URO-D gene was completely sequenced, and a long-range PCR method was developed to amplify the entire gene for mutation analysis. Four missense mutations (M165R, L195F, N304K, and R332H), a microinsertion (g10insA), a deletion (g645Delta1053), and a novel exonic splicing defect (E314E) were identified. Expression of the L195F, N304K, and R332H polypeptides revealed significant residual activity, whereas reverse transcription-PCR and sequencing demonstrated that the E314E lesion caused abnormal splicing and exon 9 skipping. Haplotyping indicated that three of the four families with the g10insA mutation were unrelated, indicating that these microinsertions resulted from independent mutational events. Screening of nine f-PCT probands revealed that 44% were heterozygous or homozygous for the common hemochromatosis mutations, which suggests that iron overload may predispose to clinical expression. However, there was no clear correlation between f-PCT disease severity and the URO-D and/or hemochromatosis genotypes. These studies doubled the number of known f-PCT mutations, demonstrated that marked genetic heterogeneity underlies f-PCT, and permitted presymptomatic molecular diagnosis and counseling in these families to enable family members to avoid disease-precipitating factors.

Porfiria cutanea tarda: detección de una mutación en la uroporfirinogena decarboxilasa mediante RT-PCR y secuenciación directa / Porphyria cutanea tarda: detection of the new mutation in the uroporphyrinogen decarboxylase intervening RT-PCR direct sequenced

La porfiria cutánea tardía familiar (PCT-F) y la porfiria hepatoeritropoyética (PHE), son dos porfirias cutáneas causadas por la deficiencia en la actividad de la Uroporfirinógeno Decarboxilasa (URO-D), que es la quinta enzima del camino biosintético del hemo y cataliza la conversión del Uroporfirinógeno(UROgen) a Coproporfirinógeno (COPROgen). La PCT-F es dominante y la actividad de la URO-D está reducida a un 50 por ciento en todos los tejidos mientras que la PHE es recesiva y en ella la activcidad de la URO-D es sólo de un 5-10 por ciento del valor normal. El gen de la URO-D está compuesto por 10 exones dentro de 3 kb. Partiendo de 15 ml de sangre entera, y realizando separación de linfocitos, extracción de ARN, RT-PCR y secuenciación directa de las casi 1,2 del ADNc de la URO-D, se ha encontrado en un paciente argentina con PCT-F una mutación nueva caracterizada por la deleción del exón 9, La PCR y secuenciación del ADN genómico revelo que la deleción es causada por la transición G A en la última base del exón 9 que afecta la maduración ("splicing") del mensajero ya que inactivaría el sitio doner de "splicing" del intrón 9, como consecuencia se produce la unión entre el exón 8 y 10 lo cual a su vez lleva a un corrimiento de marco de lectura, que predice la síntesis de una proteína truncada con una perdida total de casi el 20 por ciento de sus aminoácidos(AU)

Porfiria cutanea tarda: detección de una mutación en la uroporfirinogena decarboxilasa mediante RT-PCR y secuenciación directa / Porphyria cutanea tarda: detection of the new mutation in the uroporphyrinogen decarboxylase intervening RT-PCR direct sequenced

La porfiria cutánea tardía familiar (PCT-F) y la porfiria hepatoeritropoyética (PHE), son dos porfirias cutáneas causadas por la deficiencia en la actividad de la Uroporfirinógeno Decarboxilasa (URO-D), que es la quinta enzima del camino biosintético del hemo y cataliza la conversión del Uroporfirinógeno(UROgen) a Coproporfirinógeno (COPROgen). La PCT-F es dominante y la actividad de la URO-D está reducida a un 50 por ciento en todos los tejidos mientras que la PHE es recesiva y en ella la activcidad de la URO-D es sólo de un 5-10 por ciento del valor normal. El gen de la URO-D está compuesto por 10 exones dentro de 3 kb. Partiendo de 15 ml de sangre entera, y realizando separación de linfocitos, extracción de ARN, RT-PCR y secuenciación directa de las casi 1,2 del ADNc de la URO-D, se ha encontrado en un paciente argentina con PCT-F una mutación nueva caracterizada por la deleción del exón 9, La PCR y secuenciación del ADN genómico revelo que la deleción es causada por la transición G A en la última base del exón 9 que afecta la maduración ("splicing") del mensajero ya que inactivaría el sitio doner de "splicing" del intrón 9, como consecuencia se produce la unión entre el exón 8 y 10 lo cual a su vez lleva a un corrimiento de marco de lectura, que predice la síntesis de una proteína truncada con una perdida total de casi el 20 por ciento de sus aminoácidos

Acción fotodinámica y no-fotodinámica de las porfirinas sobre la aminolevulico dehidrasa en sangre normal y de pacientes con porfiria cutanea tardia (AU) / Photodinamic action and non-photodinamic action of the porphyrins in aminolevuleico dehydrase in normal blood, and patients with porphyria cutanea tarda

Se ha investigado la acción de concentraciones variables de uroporfirina I, uroporfirinógeno I y mezclas de porfirina aisladas de plasma y orina de pacientes porfíricos sobre la actividad de la alfa-aminolevúlico dehidrasa (ALA-D) de sangre de individuos normales y pacientes con PCT, en diferentes condiciones de iluminación, a 37-C y luego de 2 horas de exposición a la porfirina. La Uro I y el Urogen I inactivan la enzima en la oscuridad, efecto dependiente de la concentración que llega al 30-60% a valore de 10 AM del tetrapirrol. El Urogen I es un inhibidor más efectivo que la Uro I. La presencia de cantidades variables de mezclas de porfirinas aisladas del plasma y orina de pacientes con PCT, en la enzima de sangre normal y porfírica, produce también una inactivación independiente y una dependiente de la luz que aumenta a concentraciones crecientes de la mezcla, a partir de un valor umbral del orden de 1 - 1,5 AM por debajo del cual, los pigmentos no ejercen ningún tipo de inhibición (AU)

Acción fotodinámica y no-fotodinámica de las porfirinas sobre la aminolevulico dehidrasa en sangre normal y de pacientes con porfiria cutanea tardia (AU) / Photodinamic action and non-photodinamic action of the porphyrins in aminolevuleico dehydrase in normal blood, and patients with porphyria cutanea tarda

Se ha investigado la acción de concentraciones variables de uroporfirina I, uroporfirinógeno I y mezclas de porfirina aisladas de plasma y orina de pacientes porfíricos sobre la actividad de la alfa-aminolevúlico dehidrasa (ALA-D) de sangre de individuos normales y pacientes con PCT, en diferentes condiciones de iluminación, a 37-C y luego de 2 horas de exposición a la porfirina. La Uro I y el Urogen I inactivan la enzima en la oscuridad, efecto dependiente de la concentración que llega al 30-60% a valore de 10 µM del tetrapirrol. El Urogen I es un inhibidor más efectivo que la Uro I. La presencia de cantidades variables de mezclas de porfirinas aisladas del plasma y orina de pacientes con PCT, en la enzima de sangre normal y porfírica, produce también una inactivación independiente y una dependiente de la luz que aumenta a concentraciones crecientes de la mezcla, a partir de un valor umbral del orden de 1 - 1,5 µM por debajo del cual, los pigmentos no ejercen ningún tipo de inhibición