Carlos Wolff

Diagnosis and treatment of the acute porphyrias: an interdisciplinary challenge.

The porphyrias comprise a group of fascinating disorders resulting from predominantly inherited as well as acquired deficiencies of one of the eight enzymes along the pathway of heme biosynthesis. On the basis of clinical aspects, the different types of porphyrias can be classified in acute and non-acute forms. However, an exact classification is often difficult since the porphyrias might reveal unspecific clinical symptoms and/or overlapping biochemical features. In particular, this is true for the acute porphyrias which can present with life-threatening acute neurovisceral attacks that require immediate medical intervention. Due to the multiple facets of these disorders, the diagnosis and treatment of the acute porphyrias should always imply a close interdisciplinary collaboration to serve patients and their families most effectively.

Identification of a Founder Mutation in the Protoporphyrinogen Oxidase Gene in Variegate Porphyria Patients from Chile

Variegate porphyria (VP; OMIM 176200) is characterized by a partial defect in the activity of protoporphyrinogen oxidase (PPO), the seventh enzyme of the porphyrin-heme biosynthetic pathway. The disease is usually inherited as an autosomal dominant trait displaying incomplete penetrance. In an effort to characterize the spectrum of molecular defects in VP, we identified 3 distinct mutations in 6 VP families from Chile by PCR, heteroduplex analysis, automated sequencing, restriction enzyme digestion and haplotyping analysis. The mutations consisted of 2 deletions and 1 missense mutation, designated 1239delTACAC, 1330delT and R168H. The occurrence of the missense mutation R168H had been reported previously in American, German and Dutch VP families, suggesting that this may represent a frequent recurrent mutation. Interestingly, the mutation 1239delTACAC was found in patients from 4 unrelated families living in different parts of Chile, suggesting that it might represent a common mutation in Chile. Haplotype analysis using 15 microsatellite markers which closely flank the PPO gene on chromosome 1q22, spanning approximately 21 cM, revealed the presence of R168H on different haplotypes in 6 VP patients from 3 unrelated families. In contrast, we found the occurrence of 1239delTACAC on the same chromosome 1 haplotype in 11 mutation carriers from 4 unrelated families with VP. These findings are consistent with R168H representing a hotspot mutation and 1239delTACAC existing as a founder mutation in the PPO gene. Our data comprise the first genetic studies of the porphyrias in South America and will streamline the elucidation of the genetic defects in VP patients from Chile by allowing an initial screening for the founder mutation 1239delTACAC.

The molecular basis of porphyria cutanea tarda in Chile: Identification and functional characterization of mutations in the uroporphyrinogen decarboxylase gene

Abstract:  The porphyrias are heterogeneous disorders arising from predominantly inherited catalytic deficiencies of specific enzymes in heme biosynthesis. Porphyria cutanea tarda (PCT) results from a decreased activity of uroporphyrinogen decarboxylase, the fifth enzyme in heme biosynthesis. The disorder represents the only porphyria that is not exclusively inherited monogenetically. In PCT, at least two different types can be distinguished: acquired/sporadic (type I) PCT, in which the enzymatic deficiency is limited to the liver and inherited/familial (type II) PCT, which is inherited as an autosomal dominant trait with a decrease of enzymatic activity in all tissues. In an effort to characterize the molecular basis of PCT in Chile, we identified eight mutations in 18 previously unclassified PCT families by polymerase chain reaction, heteroduplex analysis, and automated sequencing. To study the role of these mutations in disease causality, in vitro expression of all novel missense mutations was studied. Our results indicate that the frequency of familial PCT in Chile is approximately 50%, thus, to our knowledge, representing the highest incidence of familial PCT reported to date. The data further emphasize the molecular heterogeneity in type II PCT and demonstrate the advantages of molecular genetic techniques as a diagnostic tool and in the detection of clinically asymptomatic mutation carriers.

A Chilean boy with severe photosensitivity and finger shortening: the first case of homozygous variegate porphyria in South America

A 7‐year‐old Chilean boy presented with severe photosensitivity, blistering, erosions and scarring on sun‐exposed areas of the body since the age of 6 months. Additionally, he showed a short stature and shortening of the fingers. Laboratory examination revealed greatly elevated protoporphyrin levels in the blood. Such biochemical findings can be observed in homozygous variants of usually autosomal dominantly inherited acute porphyrias such as variegate porphyria (VP) and hereditary coproporphyria, which usually do not become manifest before the second or third decade of life in heterozygotes. Using polymerase chain reaction‐based techniques we identified a missense mutation in exon 7 on the paternal allele and a frameshift mutation in exon 13 on the maternal allele of the protoporphyrinogen oxidase gene that harbours the mutations underlying VP. This is the first homozygous case of VP in South America. As VP represents the most frequent type of acute porphyria not only in Chile but also in South Africa, more such cases could be expected in the future, particularly because a founder mutation for this disease has already been described in the Chilean and South African population.

Porfiria y embarazo

BACKGROUND Hormonal changes, prolonged fasting due to vomiting and some medications used during pregnancy, may cause an acute crisis of porphyria, sometimes unveiling a latent disease. Porphyria may also affect the evolution of pregnancy. AIM To study the reciprocal influence in the evolution of both pregnancy and porphyria. MATERIAL AND METHODS Retrospective review of medical records of women with porphyria followed by the authors. If additional information was required, an additional visit to the clinic was scheduled. The characteristics of pregnancy, delivery and the newborn were analyzed. RESULTS Information about 60 pregnancies in 17 women aged 18 to 43 years was gathered. Among women with acute porphyria, one with coproporphyria had four pregnancies, nine with variegate porphyria had a total of 34 pregnancies and two with acute intermittent porphyria had six pregnancies. Five women with porphyria cutánea had a total of 16 pregnancies. Influence of porphyria in pregnancy: Compared to the general population, no differences were observed in birth weight of newborns, frequency of gestational hypertension, term or preterm deliveries of live newborns, spontaneous abortions nor in tubal pregnancies; there was a high frequency of hyperemesis gravidarum. Influence of pregnancy in porphyria: 5 of the 12 patients with acute porphyria, had an acute porphyria crisis, 3 during the puerperal period and 2 during pregnancy (42% of women, 11% of pregnancies). All these crisis were associated to the administration of medications. All patients survived. Two of these women had six ulterior pregnancies without complications. CONCLUSIONS Women with porphyria that become pregnant have a higher frequency of hyperemesis gravidarum. Crises among women with acute porphyrias, were always associated with the use of potentially dangerous medications.

Analysis of the intronic single nucleotide polymorphism rs#466452 of the nephrin gene in patients with diabetic nephropathy

We present the analysis of an intronic polymorphism of the nephrin gene and its relationship to the development of diabetic nephropathy in a study of diabetes type 1 and type 2 patients. The frequency of the single nucleotide polymorphism rs#466452 in the nephrin gene was determined in 231 patients and control subjects. The C/T status of the polymorphism was assessed using restriction enzyme digestions and the nephrin transcript from a kidney biopsy was examined. Association between the polymorphism and clinical parameters was evaluated using multivariate correspondence analysis. A bioinformatics analysis of the single nucleotide polymorphism rs#466452 suggested the appearance of a splicing enhancer sequence in intron 24 of the nephrin gene and a modification of proteins that bind to this sequence. However, no change in the splicing of a nephrin transcript from a renal biopsy was found. No association was found between the polymorphism and diabetes or degree of renal damage in diabetes type 1 or 2 patients. The single nucleotide polymorphism rs#466452 of the nephrin gene seems to be neutral in relation to diabetes and the development of diabetic nephropathy, and does not affect the splicing of a nephrin transcript, in spite of a splicing enhancer site.

Tratamiento con insulina aspártica bifásica en pacientes con diabetes en mal control metabólico: Experiencia clínica programada

BACKGROUND Biophasic insulin aspart (InAsBi) is a mixture of 30% of rapid acting soluble aspart insulin and 70% aspart insulin retarded with protamine. The soluble portion reduces postprandial serum glucose rises and the retarded portion reduces basal glucose levels. AIM To assess the efficacy of biphasic insulin aspart in diabetics with a bad metabolic control. MATERIAL AND METHODS Multicentríc study that included diabetic patients with a glycosilated hemoglobin over 7% that were transferred to treatment with InAsBi, given in one to three daily doses, according to glycemic control and followed for 12 weeks. At the end of follow up, glycosilated hemoglobin levels (HbA1c) were measured again. RESULTS One hundred ninety six patients were enrolled and 154, age 59+/- 12 (84 females), completed the follow up. HbA 1 c levels decreased in at least 1% in 96 and increased in eight cases. In the total group HbA1c decreased from 10.1+/- 1.7 to 8.4+/-1.4% (p <0.01). Those with higher initial values and with oral therapy, had the greatest reductions. At the end of the observation period, 29 patients received one daily dose of InAsBi, 114 two doses and 11 three doses. Two patients had allergy, one systemic and one in the injection site. CONCLUSIONS In this group of diabetic patients with a bad metabolic control, the use of InAsBi was associated with a significant reduction of glycosilated hemoglobin levels.

Genetics of Endothelial Damage Associated to Diabetes Mellitus Type 2

Diabetes mellitus (DM) is a serious worldwide public health problem due to its frequency, chronic complications and their high associated costs. This disease is considered a multifactorial pathology that involves insulin resistance and is associated to obesity, dyslipidemia, endothelial dysfunction, inflammation and hypertension (Petersen & Shulman, 2006). Type 2 diabetes (DM2) is one of the most common diseases in the developed world and is recognized now as a global burden (van Dieren et al., 2010). Released in 2000, the initial edition of the Diabetes Atlas estimated the global prevalence of this disease at 4.6%, representing 151 million people, and projected an increase to 333 million people by 2025. On the basis of the most recent evidence, the current Diabetes Atlas has predicted that the number of people with diabetes will have risen to a staggering 438 million or 7.8% of the world`s population in 2030 (Colagiuri, 2010; www.diabetesatlas.org). The development of DM2 requires the involvement of genetic and environmental factors such as android obesity and sedentary lifestyle that determine hyposecretion of insulin in response to glucose stimulation and a decreased insulin action in peripheral tissues. Most of the complications associated to DM2 are related to pathophysiological alterations of the vascular endothelium, and are the main cause of morbidity and mortality among DM patients. Endothelial dysfunction is the initial event that predisposes the vascular wall to diverse alterations leading to the establishment of so-called cardiovascular complications of diabetes. Known risk factors of diabetic complications such as hyperglycemia, hypertension and dyslipidemia stimulate the production of reactive oxygen species (ROS) in the vascular wall. Hyperglycemia is now considered a key causal factor in the development of chronic complications of diabetes (Giuliano et al., 2008). The vascular endothelium consists of endothelial cells and is a type of monostratified squamous epithelium that lines the inner surface of all blood vessels including the heart. Its crucial role is to regulate the vascular tone and it also has a structural function. In addition, the vascular endothelium normally inhibits platelet and leukocyte adhesion to the vascular surface and maintains a balance between profibrinolytic and prothrombotic activities

Contents Vol. 14, 2001

2nd Joint Meeting International Psoriasis Symposium and European Congress on Psoriasis San Francisco, Calif., June 19–24, 2001 136 Oral Presentations 176 Poster Presentations

Carbohydrate metabolism in porphyria

A high proportion of patients with porphyria cutanea tarda (PCT) show a hyperinsulinemic response to the oral glucose tolerance test (OGTT) attributed to the hepatopathy also frequent in this disease. We propose that hyperinsulinemia is the main feature and source of carbohydrate metabolic alterations present in both chronic and acute types of porphyria. In order to verify this hypothesis, the insulinemic response to the OGTT was studied in 12 healthy controls, 18 PCT patients and 14 patients with acute types of porphyria. Of the PCT patients, 22% showed an altered response to the OGTT, in agreement with other authors. The frequency of altered hyperinsulinemic response in PCT patients was similar to that in acute-type porphyria patients. However, the intensity of this alteration was significantly higher in PCT than in acute-type porphyria patients. Among the PCT patients with hyperinsulinemic response, some showed evidence of hepatic damage, while others did not. On the other hand, patients with acute types of porphyria and chronic hepatic damage, demonstrated by histology procedures, did not show the hyperinsulinemic phenomenon. In summary, both PCT and acute-type porphyria patients show a higher frequency of hyperinsulinemic response to the OGTT than the general population. This hyperinsulinemic response cannot be attributed to concomitant hepatic damage, but hepatopathy can intensify the insulinemic response.