Nine novel mutations in the hydroxymethylbilane synthase gene of Polish patients with acute intermittent porphyria.
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Adult↗
Biomedical subjects
E I Minder
Publications and source records attributed to E I Minder.
Mutation hotspots in the human porphobilinogen deaminase gene: recurrent mutations G111R and R173Q occurring at CpG motifs.
Acute intermittent porphyria (AIP) is an inherited disorder in the haem biosynthetic pathway caused by a partial deficiency of porphobilinogen (PBG) deaminase. To date, more than 200 different mutations have been identified in the PBG deaminase gene (PBGD) in AIP patients from various countries and ethnic groups. While the majority of the PBGD gene mutations, including most of the mutations occurring at CpG dinucleotides, are family-specific, a few CpG mutations have been observed in a number of AIP patients of European origin. To study the origin of these common CpG mutations, eight intragenic single-nucleotide polymorphisms (SNPs) in the PBGD gene, as well as eight microsatellites flanking the gene in chromosome 11 were used to construct haplotypes in six AIP families of German, Polish and Swiss origins who carried either G111R (4707G>A) or R173Q (6391G>A) mutations. Among the three R173Q families, three distinct haplotypes were found to be cosegregated with the mutation. One Swiss and one German G111R family shared partially an intragenic and its extended microsatellite haplotype, whereas the Polish G111R family showed a unique haplotype. These results indicated that the recurrent CpG mutations that exist in the European AIP population can be either of ancestral origins or derived from de novo events.
Chromosome Mapping↗
A genotype-phenotype correlation between null-allele mutations in the ferrochelatase gene and liver complication in patients with erythropoietic protoporphyria.
Erythropoietic protoporphyria (EPP), an inborn error of heme metabolism, causes in the majority of the patients only a symptom of photosensitivity. However, around 2% of the EPP sufferers develop liver complication in the form of liver cirrhosis and progressive liver failure. Mutations in the human ferrochelatase (FECH) gene causing EPP are highly heterogeneous and mostly family-specific. Actually, 62 FECH mutations have been published, 48 of them are "null allele" mutations inducing the formation of a truncated protein. The remaining 14 are missense mutations. In contrast to the null allele mutations, the latter lead to substitution of a single amino acid residue in the protein molecule and generate an enzyme that, although functionally impaired, is in its full length. In order to study the association between "null allele" mutation and liver complication, we combined our data with those in the literature. A total of 112 EPP patients were counted among 93 EPP families with a known FECH mutation. All 18 EPP patients who had severe liver complication carried a "null allele" mutation. In contrast, none of the 20 patients who carried a missense mutation had developed liver complication till the time of study (Fisher's exact test, p<0.05). High protoporphyrin blood concentration are considered to be a sign of an increased risk of liver disease. No correlation of protoporphyrin blood level with the type of mutation, was found, if patients with overt liver disease were excluded from the sample. Furthermore, no significant association of the liver complication with the location of the mutation within the FECH gene was found (Fisher exact test p = 0.46). These available data indicate a significant genotype-phenotype correlation between "null allele" mutation and protoporphyrin related liver disease in EPP. Although the risk for a EPP patient with a missense mutation to develop liver disease cannot be totally eliminated based on these data, it is comparably low.
Alleles↗
Elevation of troponin I in sepsis and septic shock.
OBJECTIVE: To detect myocardial damage in severe systemic inflammation by cTnI measurements in patients without acute coronary syndromes. DESIGN: Prospective case control study. SETTING: Tertiary referral center. PARTICIPANTS: Twenty patients with sepsis, septic shock, and systemic inflammatory response syndrome (SIRS) were examined and compared to controls without coronary artery disease or myocarditis. MEASUREMENTS AND RESULTS: cTnI levels were assessed in patients with SIRS, sepsis, and septic shock. Eight patients (two female/six male) suffered from septic shock, nine (three female/six male) from sepsis without shock, and three (three male) from SIRS. Seventeen patients (85%) showed elevated cTnI (median 0.57 microg/l; 0.17-15.4), whereas no patient in the control group showed elevated cTnI (P < 0.0001). Six patients (30%),--three with septic shock and three with sepsis--died during hospitalization, five of them with elevated cTnI. Four out of five autopsies showed normal coronary arteries. Coronary angiography, autopsy, and stress echocardiography ruled out significant coronary artery disease in ten cTnI-positive patients (59%). In 41 % of cTnI-positive patients, Streptococcus pneumoniae could be cultured, whereas no cTnI-negative or control patient showed signs of infection due to S. pneumoniae. CONCLUSION: Cardiac troponin I was elevated in 85% of patients with sepsis, septic shock or SIRS in our study. A high percentage showed infection caused by S. pneumoniae. In what way microorganisms cause cTnI elevations is not yet understood.
Aged↗
Haplotype analysis in determination of the heredity of erythropoietic protoporphyria among Swiss families.
Defects in the human ferrochelatase gene lead to the hereditary disorder of erythropoietic protoporphyria. The clinical expression of this autosomal dominant disorder requires an allelic combination of a disabled mutant allele and a low-expressed nonmutant allele. Unlike most other erythropoietic protoporphyria populations, mutations identified among Swiss erythropoietic protoporphyria families to date have been relatively homogeneous. In this study, genotype analysis was conducted in seven Swiss erythropoietic protoporphyria families, three carrying mutation Q59X, two carrying mutation insT213, and two carrying mutation delTACAG(580-584). Three different haplotypes of five known intragenic single nucleotide polymorphisms, namely -251 A/G, IVS1-23C/T, 798 G/C, 921 A/G, and 1520C/T, were identified. Each haplotype was shared by families carrying an identical mutation in the ferrochelatase gene indicating a single mutation event for each of the three mutations. These mutations have been present in the Swiss erythropoietic protoporphyria population for a relatively long time as no common haplotypes of microsatellite markers flanking the ferrochelatase gene were found, except of two conserved regions, telomeric of the insT213 allele and centromeric of the delTACAG(580-584)allele, each with a size > 3 cM. Among the nonmutant ferrochelatase alleles, patients from six erythropoietic protoporphyria families shared a common haplotype [-251G; IVS1-23T] of the first two single nucleotide polymorphisms. An exception was the haplotype [-251 A; IVS1-23C] identified in the index patient of one erythropoietic protoporphyria family. These results supported the recent findings that the low expressed allele is tightly linked to a haplotype [-251G; IVS1-23T] of two intragenic single nucleotide polymorphisms in the ferrochelatase gene.
Family Health↗
Influence of age and gender on the clinical expression of acute intermittent porphyria based on molecular study of porphobilinogen deaminase gene among Swiss patients.
BACKGROUND: Acute intermittent porphyria (AIP) is an inherited disorder in the heme biosynthetic pathway caused by a partial deficiency of porphobilinogen (PBG) deaminase. Clinically, AIP is characterized as acute neurovisceral attacks that are often precipitated by exogenous factors such as drugs, hormones, and alcohol. An early detection of mutation carriers is essential for prevention of acute attacks by avoiding precipitating factors. This study was aimed at analyzing genetic defects causing AIP among Swiss families to further investigate aspects concerning the clinical expression of the disease. MATERIALS AND METHODS: The PBGD gene of index patients from 21 Swiss AIP families was systematically analyzed by denaturing gradient gel electrophoresis of polymerase chain reaction (PCR) amplified DNA fragments and direct sequencing. RESULTS: Five new mutations insA503, del L170, T190I, P241S, and R321H, as well as three known mutations (R26H, R173Q and W283X) were detected. Twelve of the 21 index patients (57%) carried the prevalent mutation W283X previously found among the Swiss AIP population. Family-specific mutations were then screened among relatives of the index patients. Among the 107 studied individuals, 58 carried a PBGD gene mutation--30 were overt AIP patients and 28 were asymptomatic carriers. The apparent rate of overt disease in the study cohort was 52%, which is significantly higher than the previously reported penetrance of 10-20%. To further examine the clinical expression of AIP, the cumulative life-time risk was calculated among 58 mutation-positive individuals after stratifying for age. The result shows a linear increase of the percentage of the symptomatic patients with age, reaching up to 75% among carriers aged over 60. Moreover, statistical analysis of the gender distribution among patients and asymptomatic carriers indicated that the disease was more frequently expressed among females than males (Fisher's exact test two sided, p= (0.001). CONCLUSIONS: This comprehensive search for genetic defects in the PBGD gene confirmed the existence of a prevalent mutation W283X among Swiss AIP patients, as well as a number of family-private mutations. Genetic analysis laid a groundwork for further studies such as the effects of gender and age on the clinical expression of AIP.
Adolescent↗
New insights into the pathogenesis of erythropoietic protoporphyria and their impact on patient care.
UNLABELLED: Erythropoietic protoporphyria (EPP, MIM 177000) is an inherited disorder caused by a partial deficiency of ferrochelatase (FECH) which catalyses the chelation of iron into protoporphyrin to form haem. The majority of EPP patients experience solely a painful photosensitivity whereas a small number of them develop liver complications due to the accumulation of excessive amount of protoporphyrin in the liver. EPP is considered to be an autosomal dominant disorder, however, with a low clinical penetrance. To date, a total of 65 different mutations have been identified in the FECH gene of EPP patients. Among the 89 EPP patients who carry a "null allele" mutation which results in the formation of a truncated protein, 18 of them developed EPP-related liver complications. None of the 16 missense mutations identified among 19 patients on the other hand, have been associated with liver disease (P = 0.038). The allelic constellation of an overt patient consists of a mutated FECH allele and a "low expressed" normal allele and that of an asymptomatic carrier, a combination of a mutated and a normally expressed FECH allele. The identification of the "low expressed" allele is facilitated by haplotype analysis using two single nucleotide polymorphisms, -251 A/G in the promoter region and IVS1-23C/T. At the current time when only partially effective therapies are available, the disclosures of both "null allele" and the "low expression" mechanisms will improve patient management. CONCLUSION: While covering the important clinical aspect of erythropoietic protoporphyria, this article emphasises the latest achievements in the molecular genetics of the disorder.
Alleles↗
Mutations in the ferrochelatase gene of four Spanish patients with erythropoietic protoporphyria.
Erythropoietic protoporphyria is a hereditary disorder of porphyrin metabolism caused by mutations in the ferrochelatase gene. Ferrochelatase catalyzes the chelation of ferrous iron into protoporphyrin IX to form heme. Mutation analysis was performed in four Spanish erythropoietic protoporphyria families resulting in the identification of four different mutations in the ferrochelatase gene. Two of them were novel mutations, a missense mutation (1157 A-->C, H386P) and a frameshift mutation (843delC) found in two Spanish families, respectively. The third and the forth Spanish patients carried already published ferrochelatase gene mutations, a nonsense mutation (343C-->T, R115X) and a missense mutation (557T-->C, I186T), respectively. The newly described frameshift mutation (843delC) predicted formation of an abrupt mRNA. The deleterious effect of His386 to Pro substitution as a result of mutation 1157 A-->C on the ferrochelatase activity was investigated by expressing the mutant ferrochelatase in Escherichia coli. The mutant ferrochelatase exhibited only 0.8% of the wild-type ferrochelatase activity. Prediction of the secondary structure of ferrochelatase suggested that the H386P mutation disrupted the original alpha-helical structure by way of introducing a turn, a rather drastic structural change of the enzyme sufficient to cause activity loss.
Electrophoresis, Polyacrylamide Gel↗
Systematic analysis of molecular defects in the ferrochelatase gene from patients with erythropoietic protoporphyria.
Erythropoietic protoporphyria (EPP; MIM 177000) is an inherited disorder caused by partial deficiency of ferrochelatase (FECH), the last enzyme in the heme biosynthetic pathway. In EPP patients, the FECH deficiency causes accumulation of free protoporphyrin in the erythron, associated with a painful skin photosensitivity. In rare cases, the massive accumulation of protoporphyrin in hepatocytes may lead to a rapidly progressive liver failure. The mode of inheritance in EPP is complex and can be either autosomal dominant with low clinical penetrance, as it is in most cases, or autosomal recessive. To acquire an in-depth knowledge of the genetic basis of EPP, we conducted a systematic mutation analysis of the FECH gene, following a procedure that combines the exon-by-exon denaturing-gradient-gel-electrophoresis screening of the FECH genomic DNA and direct sequencing. Twenty different mutations, 15 of which are newly described here, have been characterized in 26 of 29 EPP patients of Swiss and French origin. All the EPP patients, including those with liver complications, were heterozygous for the mutations identified in the FECH gene. The deleterious effect of all missense mutations has been assessed by bacterial expression of the respective FECH cDNAs generated by site-directed mutagenesis. Mutations leading to a null allele were a common feature among three EPP pedigrees with liver complications. Our systematic molecular study has resulted in a significant enlargement of the mutation repertoire in the FECH gene and has shed new light on the hereditary behavior of EPP.
Adolescent↗
Rapid molecular diagnosis of erythropoietic protoporphyria among Swiss patients.
Erythropoietic protoporphyria (EPP) is an autosomal dominant inherited disorder with incomplete penetrance. It is caused by partial deficiency of ferrochelatase, the last enzyme in the heme biosynthetic pathway. Measurement of protoporphyrin concentrations in red cells and feces, although sufficient for diagnosis of symptomatic EPP patients, fails to detect asymptomatic gene carriers. We have developed a molecular diagnostic procedure for rapid and reliable screening of five known mutations in the ferrochelatase gene among Swiss EPP patients in a single denaturing gradient gel electrophoresis (DGGE) gel.
Electrophoresis, Polyacrylamide Gel↗
Age-dependent reference values of urinary porphyrins in children.
To establish age-dependent reference ranges for the 3 major urinary porphyrins, uroporphyrin, coproporphyrin I and coproporphyrin III, concentrations were measured in random urine specimens from 198 children aged 0.5 to 16 and 18 new-borns by HPLC. All three porphyrins displayed unique age-dependencies. The highest coproporphyrin I concentration was observed in the new-born period, which could be explained by a physiologically under-developed excretion system (via bile and faeces) for this particular porphyrin. Coproporphyrin III excretion reached its highest value in children between ages 1 and 2. Of the three porphyrins, coproporphyrin III concentration showed the closest correlation with the total haem synthesis in childhood. A relatively broad concentration range was found for uroporphyrin in all tested age-groups, the highest mean concentration being in the new-born period. Quantification of each individual urinary porphyrin enables the diagnosis of certain disorders which otherwise cannot be achieved by the total porphyrin determination. As an example of the clinical application of these reference ranges, a case of bronze baby syndrome is discussed.
Adolescent↗
Human ferrochelatase: a novel mutation in patients with erythropoietic protoporphyria and an isoform caused by alternative splicing.
Erythropoietic protoporphyria (EPP), attributable to deficiency of ferrochelatase activity (FECH), is characterised mainly by cutaneous photosensitivity. To define the molecular defect in two EPP-affected siblings and their parents in a Swiss family, ferrochelatase cDNA was amplified by the polymerase chain reaction (PCR) and subjected to sequence analysis. A 5-bp deletion (T580-G584) was identified on one allele of the ferrochelatase gene in both patients and their mother. Screening of the mutation among family members of RsaI digestion of PCR-amplified genomic DNA revealed autosomal dominant inheritance associated with abnormal protoporphyrin concentration and enzyme activity. We also isolated ferrochelatase cDNAs containing a 18-bp insertion (part of the intron 2 sequence) between exons 2 and 3; this corresponded to six extra amino acids (YESNIR) inserted between Arg-65 and Lys-66 of the known ferrochelatase. This isoform was identified initially in mRNAs derived from both alleles of the ferrochelatase gene in one patient. Its existence was confirmed in six additional EPP patients, in five out of seven controls, and in four different cell lines (fibroblast, muscle, hepatoma and myelogenous leukaemia). This isoform, roughly 20% of the total ferrochelatase mRNA, was generated through splicing at a second donor site in intron 2 and its presence was not linked to EPP.
Adolescent↗
Development of a gas chromatography-mass spectrometry method for determination of ketamine in plasma and its application to human samples.
A sensitive and precise gas chromatography-mass spectrometry method with selected ion monitoring has been developed for identification and quantification of the phencyclidine derivative ketamine in human plasma. The assay is based on an alkaline extraction from aqueous to organic solvent from plasma and an efficient gas chromatographic separation on a DB-5 capillary column. The analytical procedure has a coefficient of variation of 0.7-6.2% and from 1.3 to 8.7% within-day and from day-to-day analysis, respectively. The low level of sensitivity was 10 ng/ml. It was used to measure low plasma concentrations in volunteers during ketamine-induced experimental psychosis. The method is not enantio selective.
Adult↗
Recessive inheritance of erythropoietic protoporphyria with liver failure.
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Ferrochelatase↗
Lack of effect of oral charcoal in congenital erythropoietic porphyria.
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Administration, Oral↗
Molecular defects in erythropoietic protoporphyria with terminal liver failure.
We identified two additional mutations in the ferrochelatase gene in two Swiss patients with erythropoietic protoporphyria (EPP). Ferrochelatase cDNA from patients was amplified by the polymerase chain reaction (PCR) and subjected to mutation analysis by sequencing PCR products either directly or after subcloning. The first patient, who underwent liver transplantation because of terminal liver failure, was identified as having a single point mutation (C to T) at nucleotide 175 that resulted in a Gln to stop codon conversion in one allele of the gene. In the second case, in which the patient has so far no liver involvement, a two-base deletion (T899G900) was found in one allele. Frameshift as a result of the deletion creates a stop codon. This study presents two new genotypes of EPP, including one with liver failure, a rare and fatal form of EPP.
Adult↗
[Often unrecognized: erythropoietic protoporphyria].
Erythropoietic protoporphyria is an autosomal dominant hereditary disorder with irregular penetrance. Recently, the first molecular DNA defects have been published. Various courses the disease may take are illustrated by three cases. The main symptom is photosensitivity, usually beginning in early childhood. Development of gallstones at an early age is one possible complication. Terminal liver failure, a rare but fatal complication, is due to intrahepatic protoporphyrin deposition and is treatable by liver transplantation only. Possible treatment schemes for photosensitivity and for liver involvement are discussed.
Adult↗
Coproporphyrin isomers in acute-intermittent porphyria.
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Coproporphyrins↗