Clinical manifestations of porphyrin metabolism disorders

AIM: To characterize patients with various nosological unities [symbol: see text] of porphyria in accordance with their age, clinical symptoms, provoking factors, therapy and outcome. MATERIAL AND METHODS: Patients with acute intermittent porphyria (43), hereditary coproporphyria (8), variegate porphyria (3), porphyria cutanea tarda (7), hepatoerythropoietic porphyria (1), and hereditary erythropoietic porphyria (2) were studied. One patient was suspected of porphyria caused by deficiency of delta-aminolevulenic acid dehydrogenase. RESULTS: The patients were from the CIS. The overwhelming majority of them were young and middle-aged subjects. Rapid development of the disease and severe neurological symptoms were predominantly observed in patients with acute forms of porphyria. CONCLUSION: Early diagnosis of porphyrin metabolism disorders makes it possible to decrease abruptly the number of cases leading to severe complications, disability, and fatal outcome. The use of inexpensive methods of screening of porphyrin metabolism disorders provides a promising approach to solving this problem. These methods should be used in municipal hospitals. In addition, asymptomatic carriers of defective gene should be revealed at the preclinical stage using various methods of molecular genetic assay.     

Uroporphyrinogen synthase in erythrocytes in acute intermittent porphyria: new pathobiochemical aspects (author's transl)

Uroporphyrinogen synthase (EC 4.3.1.8) was determined in the erythrocytes of 380 patients, of which 21 showed clinical symptoms of acute intermittent porphyria. The normal range of a random sample was 61 +/- 23 mumol/1.h(x +/- 2s, n=302), including the activity of uroporphyrinogen cosynthase and the subsequent enzymes; when all the latter enzymes were destroyed by heating the haemolysate, the normal range for uroporphyrinogen synthase was 65 +/- 25 mumol/1.h(x +/- 2s, n=274). The respective activity of uroporphyrinogen synthase in patients with acute intermittent porphyria was 35 +/- 12, and 40 +/- 18 mumol/1.h which was significantly lower (p less than 0.001) than the control values. In the 21 cases of acute intermittent porphyria, the diagnosis had already been made from the presence of porphyrin precursors and porphyrin in the urine. In 7 of the 21 cases of acute intermittent porphyria, and in 6 relatives of the patients, the activity of the uroporphyrinogen synthase was in the overlap zone (40-50 mumol/1.h). 32 relatives of 9 of the patients with acute intermittent porphyria were investigated: 22 showed a significant decrease of uroporphyrinogen synthase, and 7 of these showed pathological urinary porphyrin precursors and porphyrin. The relative activity of uroporphyrinogen synthase in patients with acute intermittent porphyria was 57%. A decrease of the uroporphyrinogen synthase activity of greater than 30% compared with the mean of the controls is a sure indicator for the presence of a primary enzymic defect in the gene carrier for acute intermittent porphyria.     

Porphyrins, porphyrin metabolism and porphyrias. II. Diagnosis and monitoring in the acute porphyrias

The acute porphyrias constitute a group of metabolic disorders engaging enzymes in the haem synthetic chain and generally following dominant inheritance patterns. Some gene carriers are vulnerable to a range of exogenous and endogenous factors, which may trigger neuropsychiatric symptoms. Early diagnosis is of prime importance since it makes way for counselling with the aim to block the development of acute, as well as late, disease. The medical and psycho-social consequences of a porphyria diagnosis are considerable and the freedom for maldiagnosis correspondingly small. The strain imposed upon the diagnostic process makes management in specialized laboratories necessary. Inadvertent handling of the diagnostic procedures in laboratories lacking in knowledge, experience and technical competence is repeatedly the reason for harmful underdiagnosis and overdiagnosis. Gene diagnosis of the carrier condition, principally within reach in all types of acute porphyria, is of incomparable versatility and accuracy. However, despite recent great achievements in the molecular biology of porphyric disease, genomic procedures cannot replace biochemical methods in monitoring the activity and progress of the disease, or the effects of therapy. The classical methods are also useful when it comes to screening for the associated disease states. In these tasks, professional handling of the methods and skillful interpretation of the results are of paramount importance. Knowledge of the limitations and pitfalls of the procedures is a guard against maldiagnosis, which may be fatal. In the article the main diagnostic challenges are discussed; the strategy for early detection of the gene carrier state, the recognition and surveillance of the acute porphyric crisis, the evaluation of subacute/subchronic symptoms, the differential diagnoses of the cutaneous porphyrias and the monitoring of late complications.     

Porphyrins,porphyrin metabolism and porphyrias. II. Diagnosis and monitoring in the acute porphyrias

The acute porphyrias constitute a group of metabolic disorders engaging enzymes in the haem synthetic chain and generally following dominant inheritance patterns. Some gene carriers are vulnerable to a range of exogenous and endogenous factors, which may trigger neuropsychiatric symptoms. Early diagnosis is of prime importance since it makes way for counselling with the aim to block the development of acute, as well as late, disease. The medical and psycho-social consequences of a porphyria diagnosis are considerable and the freedom for maldiagnosis correspondingly small. The strain imposed upon the diagnostic process makes management in specialized laboratories necessary. Inadvertent handling of the diagnostic procedures in laboratories lacking in knowledge, experience and technical competence is repeatedly the reason for harmful underdiagnosis and overdiagnosis. Gene diagnosis of the carrier condition, principally within reach in all types of acute porphyria, is of incomparable versatility and accuracy. However, despite recent great achievements in the molecular biology of porphyric disease, genomic procedures cannot replace biochemical methods in monitoring the activity and progress of the disease, or the effects of therapy. The classical methods are also useful when it comes to screening for the associated disease states. In these tasks, professional handling of the methods and skilful interpretation of the results are of paramount importance. Knowledge of the limitations and pitfalls of the procedures is a guard against maldiagnosis, which may be fatal. In the article the main diagnostic challenges are discussed; the strategy for early detection of the gene carrier state, the recognition and surveillance of the acute porphyric crisis, the evaluation of subacute/subchronic symptoms, the differential diagnoses of the cutaneous porphyrias and the monitoring of late complications.     

The differentiation of the porphyrias by means of high pressure liquid chromatography

The analysis of faecal and urinary porphyrins by high pressure liquid chromatography (H.P.L.C.) provides characteristic profiles and facilitates rapid diagnosis of variegate (porphyria cutanea tarda hereditaria), symptomatic porphyria (porphyria cutanea tarda symptomatica), hereditary coproporphyria, acute intermittent porphyria, erythro-hepatic protoporphyria and congenital porphyria (erythropoietic porphyria).     

Increased activity of porphobilinogen deaminase in erythrocytes during attacks of acute intermittent porphyria

The activity of porphobilinogen deaminase was determined in 25 patients with acute intermittent porphyria during and after fully developed attacks of porphyria. It was found that in most cases (in 20 of 25) it was higher than 24.3 nmoles/ml erythrocytes/hour, a value considered as characteristic for acute intermittent porphyria, and that it decreased during convalescence and remission. In a proportion of these cases the decrease in the activity of the enzyme was parallelled by decreasing urinary excretion of porphobilinogen. A normal activity of porphobilinogen deaminase during an attack of porphyria can be a source of error in the differential diagnosis of porphyria.     

ED presentation of acute porphyria

Abdominal pain is a common complaint for visits to ED. Among the causes of abdominal pain, the acute porphyria may confuse emergency physicians. With wide range of unspecific symptoms and signs, acute porphyria is rarely considered as a differential diagnosis of acute abdomen in ED. Some patients even receive unnecessary surgery. There are 32 patients who visited the ED of National Taiwan University Hospital because of acute porphyric attacks over the past 13 years. Ten patients (3 males and 7 females) were diagnosed with acute porphyria for the first time at ED. The onset of age ranged from 17 to 55 years (mean, 32 years). All of our patients presented with abdominal pain but without fever, dermatologic, and neurologic symptoms that are typically presented in acute porphyria. On the average, most of them repeatedly sought for medical help because of persistent symptoms for 4 times before being definitely diagnosed and thus receiving the optimal treatment. Meanwhile, all patients needed at least 2 kinds of analgesic, and most of them needed narcotic analgesia for pain control before diagnosis. The most commonest point of tenderness is over epigastrium (7 of 10 patients). The laboratory and image studies of our patients were of no diagnostic value for acute porphyria, except for Watson-Schwartz test. In summary, our study revealed that when a patient after puberty with repetitive visits because of severe abdominal pain without reasonable causes and needs narcotics for pain control, acute porphyria should be taken into consideration.     

Rapid quantitative method using spin columns to measure porphobilinogen in urine

BACKGROUND: Large increases of urinary porphobilinogen (PBG) indicate acute porphyria, which may be due to acute intermittent porphyria, variegate porphyria, or hereditary coproporphyria. These conditions are relatively rare but share symptoms with more common conditions, such as acute surgical abdomen, and often must be ruled out rapidly. Reported quantitative methods for PBG measurement are time-consuming and inconvenient. We developed a rapid quantitative method that uses resin-packed spin columns to measure PBG in urine. Method: We applied urine to anion exchange resin in a spin column, then performed centrifugal separation and washing. PBG was eluted in 1 mol/L acetic acid and reacted with Ehrlich's reagent. After 5 min, we measured absorbance at 525, 555, and 585 nm. PBG concentration (mg/L) was calculated as 88 (A(555) - (1/2)(A(525) + A(585))). RESULTS: The reportable PBG concentration range was 0.2-15 mg/L. Between-day (total) imprecision (CV) was 8.4% at 1.2 mg/L and 3.5% at 4.4 mg/L. Comparison with our established method (x) yielded a Deming regression equation: y = 1.04x - 0.01 mg/L (R(2) = 0.98; S(y,x) = 0.87 mg/L). No interference was noted from urobilinogen or highly colored urine specimens. CONCLUSIONS: This method for PBG measurement is more rapid and precise than other methods. This test can serve as a quick screening test and facilitates batch analysis for routine quantitative testing.     

Plasma porphyrins in the porphyrias.

BACKGROUND: As an aid in the diagnosis and management of porphyria we have developed a method to fractionate and quantify plasma porphyrins and have evaluated its use in various porphyrias. METHODS: We used HPLC with fluorometric detection to measure plasma concentrations of uroporphyrin I and III, heptacarboxyl III, hexacarboxyl III, pentacarboxyl III, and coproporphyrin I and III. We studied 245 healthy subjects, 32 patients with classical porphyria cutanea tarda (PCT), 12 patients with PCT of renal failure, 13 patients with renal failure, 8 patients with pseudoporphyria of renal failure, 3 patients with acute intermittent porphyria, 5 patients with variegate porphyria, 5 patients with hereditary coproporphyria, and 4 patients with erythropoietic protoporphyria. RESULTS: Between-run CVs were 5.4-13%. The recoveries of porphyrins added to plasma were 71-114% except for protoporphyrin, which could not be reliably measured with this technique. Plasma porphyrin patterns clearly identified PCT, and its clinical sensitivity equaled that of urine porphyrin fractionation. The patterns also allowed differentiation of PCT of renal failure from pseudoporphyria of renal failure. CONCLUSIONS: The assay of plasma porphyrins identifies patients with PCT and appears particularly useful for differentiating PCT of renal failure from pseudoporphyria of renal failure.     

Acute porphyria in the emergency department

Patients with acute hepatic porphyria present with abdominal pain and neurologic abnormalities. Although the disease is uncommon, the emergency physician will occasionally encounter a patient with porphyria. The relevant pathophysiology of acute hepatic porphyria and the treatment of the patient with acute hepatic porphyria are reviewed.     

Circulating fluorocytes at the first attack of acute intermittent porphyria: A missing link in the pathogenesis

BackgroundAcute intermittent porphyria (AIP) is an autosomal dominant disorder of the haem biosynthesis resulting from a partial deficiency of hydroxymethylbilane synthase (HMBS) with incomplete penetrance. By conventional means, it is able to identify asymptomatic mutation carrier by molecular diagnosis, but one cannot reliably predict an acute porphyric attack. The presence of fluorescent red cells (fluorocytes) in AIP is probably under-recognized since AIP is a hepatic porphyria and not associated with photosensitivity.MethodsWe used an automatic image acquisition platform to detect the circulating fluorocytes at 700 nm emission in a diabetic AIP patient during acute attack. We screened the patient and her family members for the mutation on HMBS, urine porphobilinogen and circulating fluorocytes.ResultsThe patient was heterozygous for a disease-causing mutation on HMBS and several bright circulating fluorocytes were detected. We showed evidence that protoporphyrin contributed to the erythrocyte auto-fluorescence. Interestingly, asymptomatic mutation carriers with increased urine porphobilinogen did not have circulating fluorocytes. All mutation-negative family members revealed no circulating fluorocytes.ConclusionSudden decrease in plasma glucose concentration might invoke acute attack of AIP and appearance of circulatory fluorocytes. Potential of detecting fluorocytes as screening test or for predicting an acute attack of AIP in diabetes is worth investigating.     

Difficulties in diagnosis of intermittent porphyria

A case of acute intermittent porphyria (AIP) in a woman aged 51 years with a lethal outcome is reported. The diagnosis was made late because of insufficient knowledge of physicians about this disease. The article gives diagnostic criteria and methods of examination in AIP which provide timely diagnosis and adequate treatment.     

Biochemical differentiation of the porphyrias

Objectives: To differentiate the porphyrias by clinical and biochemical methods.

Design and methods: We describe levels of blood, urine, and fecal porphyrins and their precursors in the porphyrias and present an algorithm for their biochemical differentiation. Diagnoses were established using clinical and biochemical data. Porphyrin analyses were performed by high performance liquid chromatography.

Results and conclusions: Plasma and urine porphyrin patterns were useful for diagnosis of porphyria cutanea tarda, but not the acute porphyrias. Erythropoietic protoporphyria was confirmed by erythrocyte protoporphyrin assay and erythrocyte fluorescence. Acute intermittent porphyria was diagnosed by increases in urine delta-aminolevulinic acid and porphobilinogen and confirmed by reduced erythrocyte porphobilinogen deaminase activity and normal or near-normal stool porphyrins. Variegate porphyria and hereditary coproporphyria were diagnosed by their characteristic stool porphyrin patterns. This appears to be the most convenient diagnostic approach until molecular abnormalities become more extensively defined and more widely available.     

Spectrophotometric quantification of total urinary porphyrins as a screening test for porphyrias: Threshold value revisited

Objectives

The quantification of total urinary porphyrins based on spectrophotometry or spectrofluorimetry is a key screening test in cutaneous or mixed porphyria, performed before the quantitative fractionation of porphyrin isomers by chromatography. The aim of the present study was to determine the best threshold value for a spectrophotometric screening test and to estimate its diagnostic performances.

Design and methods

Data from samples sent to the laboratory between January 2006 and July 2013 from patients with a suspicion of cutaneous or mixed porphyria were retrospectively collected. The final diagnosis was based on the clinical presentation and biochemical results performed on appropriate specimens. Control samples were obtained from 91 non-porphyria patients and 58 healthy individuals and patient samples were obtained from 38 patients with symptomatic porphyria. The sensitivity and specificity of the spectrophotometric screening test were calculated at different cutoff values expressed in nmol/L and nmol/mmol creatinine using receiver operator curves.

Results and conclusion

A threshold of 18.8 nmol/mmol creatinine was considered as the best cutoff value for the screening test, achieving a sensitivity of 100% and a specificity of 93.2%.     

Variant of acute intermittent porphyria with normal erythrocyte uroporphyrinogen-I-synthase activity

A kindred in which several members have otherwise typical acute intermittent porphyria but normal erythrocyte uroporphyrinogen-I-synthase activity has been described from Finland. We studied two porphyric members of this kindred, two patients with typical acute intermittent porphyria, and two healthy controls using the delta-aminolaevulinic acid loading test and by measuring the erythrocyte enzymes of haem biosynthesis. The excretion pattern of haem precursors after the delta-aminolaevulinic loading test in the members of the kindred studied, was similar to that in typical acute intermittent porphyria suggesting an identical enzyme defect in the liver. The activity of all red cell enzymes studied was normal in the members of the kindred. The results suggest that porphyria in the kindred studied is a variant of acute intermittent porphyria, where the uroporphyrinogen-I-synthase defect is manifested in the liver but not in red cells.     

Denaturing gradient gel electrophoresis for rapid detection of latent carriers of a subtype of acute intermittent porphyria with normal erythrocyte porphobilinogen deaminase activity.

Acute intermittent porphyria is an autosomal dominant disorder defined by a partial deficiency of porphobilinogen deaminase (EC 4.3.1.8). Clinical manifestations of the disease are characterized by acute attacks of neurological dysfunction often linked to environmental factors. Early diagnosis of gene carriers is important in the prevention of attacks and is usually achieved by determining the porphobilinogen deaminase activity in erythrocytes. However, in a subtype of acute intermittent porphyria, the enzymatic defect is restricted to nonerythropoietic cells. Different mutations have already been described that account for this phenotype in two unrelated families. We previously detected asymptomatic carriers by using mutation-specific probes after in vitro amplification of the target DNA sequence. In this study, we investigated the DNA of eight unrelated subjects with the same subtype of acute intermittent porphyria by using the polymerase chain reaction, with subsequent analysis of the amplified products by denaturing gradient gel electrophoresis. Five of these patients shared the same single-base change. This technique was quite simple and efficient for detecting asymptomatic carriers. Importantly, it is potentially useful for studying families with the same phenotypic subtype of the disease and possibly different mutations in the same DNA region.     

Lipoprotein abnormalities in patients with asymptomatic acute porphyria

There have been discrepancies in reports of total cholesterol and low density lipoprotein (LDL)-cholesterol levels in patients with acute porphyria. Some studies have found that acute porphyria patients have increased levels while others do not. The aim of this study has been to evaluate the lipid profile in a series of patients with acute porphyria, in order to help clarify these differences. Serum lipoprotein levels were studied in 30 patients (25 women and five men; age:38+/-10 years) with asymptomatic acute porphyria. Controls were 30 healthy volunteers matched for age and gender. For 13 patients and 15 controls, lipoprotein lipase and hepatic lipase activities were determined. Patients exhibited increased levels of total-cholesterol, LDL-cholesterol, high density lipoprotein (HDL)-cholesterol and apolipoprotein (apo)-A1 compared with controls (P4 mmol/l in 15 patients (50%). Levels of total triglycerides, very low density lipoprotein (VLDL)-triglycerides, VLDL-cholesterol, apo-B and lipoprotein(a) were similar in patients and controls. The hepatic lipase activity tended to be lower in patients than controls (33.8+/-17.7 vs. 50.4+/-23.0 pkat/ml; P=0.05). In conclusion, in patients with asymptomatic acute porphyria an increase of total and LDL-cholesterol was found. The cardiovascular risk conferred by this factor may be attenuated by increased HDL-cholesterol and apo-A1.     

King George III, bipolar disorder, porphyria and lessons for historians

In the 1960s, Ida Macalpine and Richard Hunter, mother and son psychiatrists, stated that George III's medical records showed that he suffered from acute porphyria. In spite of well-argued criticisms by Geoffrey Dean and Charles Dent based on their extensive clinical experience of the acute porphyrias, Macalpine and Hunter were able to garnish extensive support for their claims from historians, psychiatrists, physicians and the media circus and their view is now surprisingly widely accepted. Recent research of George III's extensive medical records has shown that Macalpine and Hunter were highly selective in their reporting and interpretation of his signs and symptoms and that the diagnosis of the acute porphyria cannot be sustained. The basis for the false claims and the consequences for historians are considered and indicate that there is now an opportunity to reassess George III's contributions to events in his reign.     

Molecular diagnostics of acute intermittent porphyria

Acute intermittent porphyria (AIP) is an inherited metabolic disease with an autosomal dominant pattern of inheritance. The disease is caused by a partial deficiency of porphobilinogen deaminase (PBGD) in heme biosynthesis. Since biochemical measurements of patients and their healthy relatives overlap, the diagnosis of AIP may remain undetermined at the symptom-free phase. Mutation detection in AIP, which provides 95% sensitivity and around 100% specificity, has quickly been incorporated into good clinical practice. During an acute attack, which includes various neurovisceral symptoms, measurement of urinary porphobilinogen (PBG) is a method of choice to confirm diagnosis, and DNA testing is unnecessary at that stage. DNA testing has revealed many new patients and excluded AIP from many healthy relatives despite slightly increased excretions of porphyrin precursors and erythrocyte PBGD in the low or borderline zone. Thus, quality-assured DNA testing is accurate enough to confirm or exclude the diagnosis of AIP. The clinical utility of DNA testing is limited for those individuals whose mutation is currently unknown, in which biochemical analyses are essential and the majority of the patients can be identified using urinary PBG and erythrocyte PBGD measurements. The measurement of urinary PBG can be used to evaluate the prognosis for symptom-free individuals. Currently, DNA testing of AIP at the population level is not recommended unless the frequency of gene carriers is locally very high and large-scale population-based mutation screening is reasonable. In the future, the knowledge of gene-gene and gene-environment interactions and protein networks using gene array and proteomics technologies may provide more precise information about pathogenetic mechanisms and novel therapeutic strategies for an acute attack and the long-term complications of AIP. Increasing knowledge of pharmacogenetics may identify the patients who are at high risk for clinical manifestations.     

Psychotropic drugs in acute intermittent porphyria.

Acute intermittent porphyria is one of a group of metabolic diseases called the porphyrias that may lead to symptoms of the central nervous system during an acute exacerbation. Certain drugs such as barbiturates are known to precipitate attacks of acute intermittent porphyria, but unfortunately there is little information regarding the safety of many psychotropic drugs in this disorder, especially the newer antidepressants and atypical antipsychotics. We report a case of an elderly patient with acute intermittent porphyria who was treated with a variety of psychotropic agents for a severe depression with psychotic features. Although many of the agents did not improve the psychiatric status of the patient, all the drugs were tolerated without precipitating an episode of acute intermittent porphyria. To our knowledge, this is the first report of the safe use of sertraline, venlafaxine, olanzapine, risperidone, clozapine, buspirone, trazodone, lorazepam, and clonazepam in a patient with documented acute intermittent porphyria. Our report also supports the safety of trifluoperazine. Although response and sensitivity to drugs may vary greatly among patients with this disorder, clinicians may want to consider the possibility of the above drugs to treat psychiatric symptoms in patients with acute intermittent porphyria.