Validation of a novel patient reported tool to assess the impact of treatment in erythropoietic protoporphyria: the EPP-QoL.

BACKGROUND: A novel treatment has been developed for erythropoietic protoporphyria (EPP) (a rare condition that leaves patients highly sensitive to light). To fully understand the burden of EPP and the benefit of treatment, a novel patient reported outcome (PRO) measure was developed called the EPP-QoL. This report describes work to support the validation of this measure. METHODS: Secondary analysis of trial data was undertaken. These analyses explored the underlying factor structure of the measure. This supported the deletion of some items. Further work then explored the reliability of these factors, their construct validity and estimates of meaningful change. RESULTS: The factor analyses indicated that the items could be summarised in terms of two factors. One of these was labelled EPP Symptoms and the other EPP Wellbeing, based on the items included in the domain. EPP Symptoms had evidence to support its reliability and validity. EPP Wellbeing had poor psychometric properties. CONCLUSIONS: Based on the analysis it was recommended to drop the EPP Wellbeing domain (and associated items). EPP Symptoms, despite limitations in the development of items, showed evidence of validity. This work is consistent with the recommendations of a task force that provided recommendations regarding the development, modification and use of PROs in rare diseases.

Long-term observational study of afamelanotide in 115 patients with erythropoietic protoporphyria.

BACKGROUND: In erythropoietic protoporphyria (EPP), an inherited disease of porphyrin-biosynthesis, the accumulation of protoporphyrin in the skin causes severely painful phototoxic reactions. Symptom prevention was impossible until recently when afamelanotide became available. Afamelanotide-induced skin pigmentation has statistically significantly improved light-tolerance, although the clinical significance of the statistical effect was unknown. OBJECTIVES: To assess clinical effectiveness by recording compliance and safety during prolonged use. METHODS: We report longitudinal observations of 115 ambulatory patients with EPP, who were treated with a total of 1023 afamelanotide implants over a period of up to 8 years at two porphyria centres; one in Rome, Italy, and the other in Zurich, Switzerland. RESULTS: Since the treatment first became available in 2006, the number of patients treated with 16 mg afamelanotide implants rose continuously until June 2014, when 66% of all patients with EPP known to the porphyria centres were treated. Only three patients considered afamelanotide did not meet their expectations for symptom improvement; 23% discontinued the treatment for other, mostly compelling, reasons such as pregnancy or financial restrictions. The quality of life (QoL) scores, measured by an EPP-specific questionnaire, were 31 ± 24% of maximum prior to afamelanotide treatment, rose to 74% after starting afamelanotide and remained at this level during the entire observation period. Only minor adverse events attributable to afamelanotide, predominantly nausea, were recorded. CONCLUSION: Based on the improved QoL scores, high compliance and low discontinuation rates, we conclude that afamelanotide exhibits good clinical effectiveness and good safety in EPP under long-term routine conditions.

A homoallelic FECH mutation in a patient with both erythropoietic protoporphyria and palmar keratoderma.

BACKGROUND: Erythropoietic protoporphyria (EPP) is a hereditary disorder caused by the deficiency of ferrochelatase (FECH) in the haem biosynthetic pathway. In the majority of families, EPP is transmitted as a pseudodominant trait. Autosomal recessive form of EPP is found in only about 3% of the families. OBJECTIVES: In this study, we describe a 6-year-old boy who suffered from both EPP and palmar keratoderma. METHODS AND RESULTS: A novel homoallelic missense mutation (p.Ser318Tyr) was identified in the FECH gene. In addition, a region of homozygosity of approximately 6.8 Mb was observed in chromosome 18 of the patient by both microsatellite and SNP array. The parents of the patient, both of Palestinian (Jordanian) origin, were heterozygous for the S318Y mutation, although no history of consanguinity was known. Microsatellite genotyping identified a partial haplotype from each parent that corresponds to the region of homozygosity in the patient. Assuming S318Y is a founder mutation, the number of generations separating the two parents from their common ancestor from whom they inherited S318Y was estimated as 21.7 (95% CI 3.42­69.7). CONCLUSION: EPP was therefore inherited as an autosomal recessive trait in the family. This study confirms the association between palmar keratoderma and autosomal recessive EPP.

Identification of a recurrent mutation in the protoporphyrinogen oxidase gene in Swiss patients with variegate porphyria: clinical and genetic implications.

Variegate porphyria (VP), one of the acute hepatic porphyrias, results from an autosomal dominantly inherited deficiency of protoporphyrinogen oxidase (PPOX), the seventh enzyme in heme biosynthesis. Affected individuals can develop both cutaneous symptoms and potentially life-threatening neurovisceral attacks. Thirty unrelated VP index patients and families are currently known in the Swiss Porphyrin Reference Laboratory in Zürich. In 16 of a total of 24 genetically tested families, we detected a recurrent mutation in the PPOX gene, designated 1082-1083insC, reflecting a prevalence of 67%. Haplotype analysis revealed that 1082-1083insC arose on a common genetic background and, thus, represents a novel founder mutation in the Swiss population. Knowledge on the carrier status within a family does not only allow for adequate genetic counseling but also for prevention of the potentially life-threatening acute porphyric attacks. Hence, future molecular screening in Swiss VP patients might be facilitated by first seeking for mutation 1082-1083insC.

Variations in the length of poly-C and poly-T tracts in intron 3 of the human ferrochelatase gene.

The third intron of human ferrochelatase (FECH) gene contains according to NCBI, a poly-C (11) and a poly-T (24) tracts which are located approximately 900 bp upstream from the known splice modulating SNP IVS3-48 c/t. Ferrochelatase catalyses the last step in heme biosynthesis and a deficiency of this enzyme results in the hereditary disorder of erythropoietic protopoprhyria (EPP). During the course of mutation analysis in the FECH gene among EPP patients, we observed variations in the length of the poly-C and poly-T tracts. To study these variations, we analyzed a total of 54 individuals of Swiss and Israeli origins. Among them, 37 were control subjects (23 individuals with the genotype t/t and 14 with the genotype c/t), 10 were unrelated EPP patients (genotype c/M) and 7 were unrelated asymptomatic mutation carriers (genotype t/M). The length of poly-C tract varied from 10 to 16, that of poly-T tract from 22 to 24 in the study cohort. Statistic analysis showed that the low-expressed FECH allele (IVS3-48c) is associated with poly-C12, C13 and C15 and poly-T22. In addition, the segregation of poly-C and poly-T tracts was studied in two Israeli EPP families. Instabilities, as seen by both insertion and deletion of one nucleotide between two generations, were observed only in the poly-T tract. The function of the poly-C and poly-T tracts are yet to be explored.

A systematic review of treatment options for dermal photosensitivity in erythropoietic protoporphyria.

Erythropoietic protoporphyria (EPP) is a rare inherited disease characterized by dermal photosensitivity due to the accumulation of photosensitizer protoporphyrin IX. We performed a systematic database search on studies related to treatment of EPP. A total of 25 relevant studies were retrieved, 16 of them dealing with the application of beta-carotene. Two studies were found on each of the three substances, n-acetyl-cysteine (NAC), cysteine, and dihydroxyacetone/Lawson (henna). In addition, single studies on vitamin C, canthaxanthin and UVB treatment respectively, were located. The total number of patients in the 25 studies was 454, including 337 patients in the various beta-carotene trials. Most studies were published in the 1970's. Efficacy criteria were not standardized. Only 5 of the 25 studies were randomized and controlled trials; the rest were either open-label, uncontrolled studies or retrospective case reports. Four of the five well-designed studies suggested lack of efficacy of beta-carotene, NAC and vitamin C. The results of the beta-carotene studies were strongly contradictory and efficacy was inversely correlated with study quality. Our data confirm the opinion of experts in the field who are much more skeptical as to its efficacy than were early proponents of treatment with this agent. We conclude, that the available data are insufficient to prove efficacy of any treatments studied so far in EPP. We emphasize the necessity of high quality efficacy studies in porphyrias and in other rare diseases.

Biochemical and molecular diagnosis of erythropoietic protoporphyria in an Ashkenazi Jewish family.

Erythropoietic protoporphyria (EPP) is a rare hereditary disorder due to a partial deficiency of ferrochelatase (FECH). The genotype of EPP patients features a mutation on one allele of the FECH gene and a common hypomorphic FECH IVS3-48c on the other allele (M/c). The resulting enzyme activity in patients is ∼35% of that in normal individuals. Ferrochelatase deficiency results in the accumulation of protoporphyrin in the skin, which is responsible for the clinical symptom of cutaneous photosensitivity in patients. In this study, we report the identification of a novel FECH mutation delT23 in an 11-member EPP family of Jewish origin. Two EPP siblings shared an identical genotype of delT23/IVS3-48c (M/c). They were both photosensitive and showed highly increased erythrocyte protoporphyrin. The genotype of the patients' mother, who did not present with any EPP clinical symptoms, was delT23/IVS3-48t (M/t). The patients' father, an offspring of consanguineous parents, was homozygous IVS3-48 c/c. He exhibited a mild photosensitivity, and an increase of 4-fold in erythrocyte protoporphyrin. His FECH mRNA amount was 71% of that of genotype t/t. It is the first reported case of an individual with c/c genotype who exhibits both biochemical and clinical indications of EPP. These results suggest that IVS3-48c is a functional variant of ferrochelatase. The clinical symptoms and biochemical abnormalities in the patients' father could be the result of an interaction between genetic and environmental factors. In addition, the frequency of IVS3-48c in the Ashkenazi Jewish population was estimated at 8%, which is similar to that in the European populations.

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.

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.

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.

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.

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.

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.

Identification of a prevalent nonsense mutation (W283X) and two novel mutations in the porphobilinogen deaminase gene of Swiss patients with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is an autosomal dominant disorder caused by decreased activity of porphobilinogen deaminase (PBGD), the third enzyme in the heme biosynthetic pathway. We report the first molecular analysis of PBGD gene mutations in AIP patients of Swiss origin. The PBGD gene of 18 Swiss AIP patients was analyzed by denaturing gradient gel electrophoresis screening of the genomic DNA and direct sequencing. Thirteen of the 18 patients (72%) carried a nonsense mutation G(849)-->A, W283X. In addition, 4 different mutations including 2 novel mutations (Q217L and Q292X), were identified in the 5 remaining AIP patients originating from both German- and Italian-speaking regions of Switzerland.

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.

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.

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.

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.