The impact of basic dermatology education and training on primary healthcare providers in KwaZulu-Natal, South Africa

Background

Dermatological diseases are amongst the commonest reasons for consultation at primary care level. Yet, dermatology teaching in medical and nursing curricula is inconsistent and often insufficient to enable medical and nursing professionals to manage these conditions effectively.

Methods

We tested the knowledge of 100 doctors and 195 nurses who attended dermatology training sessions held in three health districts in the province of KwaZulu-Natal (KZN), South Africa, by using a quasi-experimental uncontrolled before-and-after study design. At the start of the session, participants were exposed to 15 slides representing common dermatological conditions; this was followed by a test. The participants then attended a series of short lectures followed by the same test. Pre- and post-intervention test scores were compared, and the results were analysed by professional status, health district and type of facility.

Results

The mean (standard deviation [SD]) pre-intervention test score was 40.6% (20.5%). Doctors scored significantly higher than nurses (p < 0.0001). There were significant differences in performance by district (p < 0.001) and type of facility (p < 0.001). The mean (SD) post-intervention score improved to 68.7% (22.5%).

Conclusion

Doctors and nurses working in the primary care sector appear to be insufficiently trained in the management of common dermatological conditions. A short period of in-service training resulted in an immediate, significant improvement in knowledge, although we did not study long-term retention beyond this. We recommend improved prequalification training in dermatology in medical and nursing schools and an expansion of continuing professional development as well as in-service training opportunities for primary care practitioners.

HIV viraemia during pregnancy in women receiving preconception antiretroviral therapy in KwaDukuza, KwaZulu-Natal

Background

Preconception antiretroviral therapy (PCART) followed by sustained viral suppression is effective in preventing mother-to-child transmission of HIV. The rates of persistent and transient viraemia in such patients have not been prospectively assessed in South Africa.

Objectives

We determined the prevalence of transient and persistent viraemia in HIV-positive women entering antenatal care on PCART and studied variables associated with viraemia.

Methods

We performed a prospective cross-sectional observational study of HIV-positive pregnant women presenting to a primary healthcare facility in KwaZulu-Natal. All had received at least 6 months of first-line PCART. Viral load (VL) was measured, patients were interviewed, adherence estimated using a visual analogue scale and adherence counselling provided. Viral load was repeated after 4 weeks where baseline VL exceeded 50 copies/mL.

Results

We enrolled 82 participants. Of them, 59 (72%) pregnancies were unplanned. Fifteen participants (18.3%) were viraemic at presentation with VL > 50 copies/mL. Of these, seven (8.5%) had viral suppression (VL < 50 copies/mL), and eight remained viraemic at the second visit. Adherence correlated significantly with viraemia at baseline. Level of knowledge correlated with adherence but not with lack of viral suppression at baseline. Socio-economic indicators did not correlate with viraemia. No instances of vertical transmission were observed at birth.

Conclusions

Approximately 20% of women receiving PCART may demonstrate viraemia. Half of these may be transient. Poor adherence is associated with viraemia, and efforts to encourage and monitor adherence are essential. The rate of unplanned pregnancies is high, and antiretroviral therapy programmes should focus on family planning needs of women in the reproductive age group to prevent viral non-suppression prior to pregnancy.

Keywords

Preconception Antiretroviral Therapy; HIV; Viraemia; Antenatal Care; Adherence.

Differentiation of breast tuberculosis and breast cancer using diffusion-weighted, T2-weighted and dynamic contrast-enhanced magnetic resonance imaging

Background

The use of multi-parametric magnetic resonance imaging (MRI) in the evaluation of breast tuberculosis (BTB).

Objectives

To evaluate the value of diffusion-weighted imaging (DWI), T2-weighted (T2W) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in differentiating breast cancer (BCA) from BTB.

Method

We retrospectively studied images of 17 patients with BCA who had undergone pre-operative MRI and 6 patients with pathologically proven BTB who underwent DCE-MRI during January 2014 to January 2015.

Results

All patients were female, with the age range of BTB patients being 23–43 years and the BCA patients being 31–74 years. Breast cancer patients had a statistically significant lower mean apparent diffusion coefficient (ADC) value (1072.10 ± 365.14), compared to the BTB group (1690.77 ± 624.05, p = 0.006). The mean T2-weighted signal intensity (T2SI) was lower for the BCA group (521.56 ± 233.73) than the BTB group (787.74 ± 196.04, p = 0.020). An ADC mean cut-off value of 1558.79 yielded 66% sensitivity and 94% specificity, whilst the T2SI cut-off value of 790.20 yielded 83% sensitivity and 83% specificity for differentiating between BTB and BCA. The homogeneous internal enhancement for focal mass was seen in BCA patients only.

Conclusion

Multi-parametric MRI incorporating the DWI, T2W and DCE-MRI may be a useful tool to differentiate BCA from BTB.

Should essays and other "open-ended"-type questions retain a place in written summative assessment in clinical medicine?

BACKGROUND

Written assessments fall into two classes: constructed-response or open-ended questions, such as the essay and a number of variants of the short-answer question, and selected-response or closed-ended questions; typically in the form of multiple-choice. It is widely believed that constructed response written questions test higher order cognitive processes in a manner that multiple-choice questions cannot, and consequently have higher validity.

DISCUSSION

An extensive review of the literature suggests that in summative assessment neither premise is evidence-based. Well-structured open-ended and multiple-choice questions appear equivalent in their ability to assess higher cognitive functions, and performance in multiple-choice assessments may correlate more highly than the open-ended format with competence demonstrated in clinical practice following graduation. Studies of construct validity suggest that both formats measure essentially the same dimension, at least in mathematics, the physical sciences, biology and medicine. The persistence of the open-ended format in summative assessment may be due to the intuitive appeal of the belief that synthesising an answer to an open-ended question must be both more cognitively taxing and similar to actual experience than is selecting a correct response. I suggest that cognitive-constructivist learning theory would predict that a well-constructed context-rich multiple-choice item represents a complex problem-solving exercise which activates a sequence of cognitive processes which closely parallel those required in clinical practice, hence explaining the high validity of the multiple-choice format.

SUMMARY

The evidence does not support the proposition that the open-ended assessment format is superior to the multiple-choice format, at least in exit-level summative assessment, in terms of either its ability to test higher-order cognitive functioning or its validity. This is explicable using a theory of mental models, which might predict that the multiple-choice format will have higher validity, a statement for which some empiric support exists. Given the superior reliability and cost-effectiveness of the multiple-choice format consideration should be given to phasing out open-ended format questions in summative assessment. Whether the same applies to non-exit-level assessment and formative assessment is a question which remains to be answered; particularly in terms of the educational effect of testing, an area which deserves intensive study.

A review of the clinical presentation, natural history and inheritance of variegate porphyria: its implausibility as the source of the 'Royal Malady'

It has been suggested that King George III of Great Britain suffered from the haem biosynthetic disorder, variegate porphyria. This diagnosis is pervasive throughout the scientific and popular literature, and is often referred to as the 'Royal Malady.' The authors believe it inappropriate to view the case for porphyria purely in terms of symptoms, as has generally been the case in his presumptive acute porphyria diagnosis. Accordingly, this review provides a current description of the natural history and clinical presentation of the porphyrias, against which we measure the case for porphyria in George III and his relatives. The authors have critically assessed the prevalence of porphyria in a population, the expected patterns and frequency of inheritance, its penetrance and its expected natural history in affected individuals, and conclude that neither George nor his relatives had porphyria, based on four principal reasons. First, the rarity of the disease mandates a very low prior probability, and therefore implies a vanishingly low positive predictive value for any diagnostic indicator of low specificity, such as a historical reading of the symptoms. Second, penetrance of this autosomal dominant disorder is approximately 40%, and one may expect to have identified characteristic clinical features of porphyria in a large number of descendants without difficulty. Third, the symptoms of both George III and his relatives are highly atypical for porphyria and are more appropriately explained by other much commoner conditions. Finally, the natural history of the illnesses reported in this family is as atypical for variegate porphyria as are their symptoms.

C-terminal deletions in the ALAS2 gene lead to gain of function and cause X-linked dominant protoporphyria without anemia or iron overload

All reported mutations in ALAS2, which encodes the rate-regulating enzyme of erythroid heme biosynthesis, cause X-linked sideroblastic anemia. We describe eight families with ALAS2 deletions, either c.1706-1709 delAGTG (p.E569GfsX24) or c.1699-1700 delAT (p.M567EfsX2), resulting in frameshifts that lead to replacement or deletion of the 19-20 C-terminal residues of the enzyme. Prokaryotic expression studies show that both mutations markedly increase ALAS2 activity. These gain-of-function mutations cause a previously unrecognized form of porphyria, X-linked dominant protoporphyria, characterized biochemically by a high proportion of zinc-protoporphyrin in erythrocytes, in which a mismatch between protoporphyrin production and the heme requirement of differentiating erythroid cells leads to overproduction of protoporphyrin in amounts sufficient to cause photosensitivity and liver disease.

A structured assessment of newly qualified medical graduates

INTRODUCTION

While there is extensive published experience with the assessment of procedural skills in undergraduate students, this is limited in newly qualified medical graduates at the time of entry to the pre-registration (internship) year. The few studies that have been published suggest that these skills are frequently deficient when objectively tested. We therefore chose to assess the competence of a group of South African medical graduates on entry to their pre-registration year.

METHODS

A total of 58 graduates of South African medical schools were assessed. Each subject participated in a 7-station objective structured clinical examination (OSCE); 6 of these assessed individual competence in phlebotomy, intramuscular injection, female pelvic examination, bladder catheterisation, tracheal intubation and prescription writing, while competence in cardiopulmonary resuscitation was assessed in a seventh station in randomly allocated teams of 3 candidates. Candidates' opinions of their own competence was sought by questionnaire.

RESULTS

There was a wide variation in competence between subjects and across the range of tasks studied. Mean scores ranged from 85.4% for phlebotomy to 55.3% for prescription writing. The average score across all stations was 67.5%, and no student obtained an overall cut-off score of 85% or more, which was established using a modified Angoff method. Subjects' assessment of their own performance was unduly optimistic; most believed that they had demonstrated competence despite clear shortcomings in technique. Objective scores for subjects who had been exposed to a structured skills laboratory programme were not significantly higher than for those who had not, although their self-assessed performance was indeed higher.

DISCUSSION

Most of the South African medical graduates who participated in this study were unable to satisfactorily perform technical procedures appropriate to the house officer on entry to the pre-registration year. This is in line with the conclusions of the few studies published in other countries. We suggest that the learning outcomes of undergraduate medical programmes should include an explicit statement of the competencies required for practice in the pre-registration year, and that these should be adequately taught and rigorously assessed before graduation.

An analysis of 112 acute porphyric attacks in Cape Town, South Africa: Evidence that acute intermittent porphyria and variegate porphyria differ in susceptibility and severity

Four forms of porphyria may present clinically with the acute attack, an episodic, severe, and potentially life-threatening manifestation characterized by abdominal and neurologic symptoms. We describe our experience with 112 consecutive attacks observed and treated in 25 patients with the 2 most common forms of acute porphyria in Cape Town, South Africa; 25 attacks in 10 patients with variegate porphyria and 87 attacks in 14 patients with acute intermittent porphyria. The remaining patient experienced more than 100 sequential, severe, and poorly remitting attacks, which are not included in our analysis. In our population, the relative risk of an acute attack in acute intermittent porphyria compared with that in variegate porphyria was 14.3 (confidence intervals, 6.3-32.7). Patients with variegate porphyria were significantly older (median age at first attack, 30 yr) than those with acute intermittent porphyria (median age at first attack, 23.5 yr; p < 0.0001), and demonstrated an equal sex ratio, whereas the male:female ratio in acute intermittent porphyria was 2:12 (p < 0.0001). There was a significant difference in the incidence of factors precipitating the acute attack. Drug exposure was a frequent precipitant of the acute attack in variegate porphyria, whereas hormonal factors were more important in acute intermittent porphyria (p < 0.00001). Patients with acute intermittent porphyria also showed a trend to earlier and more frequent recurrent acute attacks following the initial admission. Mean urine precursor levels, blood pressure, pulse rate, and heme arginate requirement were all significantly higher in patients with acute intermittent porphyria. No significant difference in the frequency of serious complications or in outcome could be shown. We describe our experience with treatment with heme arginate, and provide evidence that heme arginate results in a prompt and statistically significant improvement in symptoms. The incidence of serious complications and mortality in this series was low, confirming a trend to an increasingly good prognosis for patients with acute porphyria who receive expert treatment.

A systematic study of the clinical and biochemical expression of variegate porphyria in a large South African family

BACKGROUND

Variegate porphyria (VP) is an autosomal dominant disorder associated with deficient haem synthesis. Recent reports indicate that the clinical penetrance of VP may have been overestimated in studies which predated the availability of DNA-based testing for VP.

OBJECTIVES

To undertake a study specifically designed to assess the clinical and biochemical penetrance of VP in a kindred characterized by gene status.

METHODS

We studied a large family carrying the South African founder mutation which is known to result in almost complete haplodeficiency. All informative members were tested for the R59W mutation. Biochemical evidence of porphyria was sought by porphyrin analysis and by plasma fluorescence scanning. The presence of clinically expressed porphyria was assessed using a structured questionnaire and telephone or personal interview.

RESULTS

Of 62 informative subjects, 33 had inherited the mutation. Of 28 adults, one subject had experienced a single acute attack. She and a further 10 subjects had experienced photosensitivity. The frequency of acute attacks in this family is therefore 4% (95% confidence interval, CI 1-18%), and of photosensitivity is 39.3% (95% CI 24-58%). The sensitivity and specificity of porphyrin analysis in this family were 0.46 (95% CI 0.30-0.64) and 1.00 (95% CI 0.85-1.00), respectively, and for plasma scanning the values were 0.85 (95% CI 0.58-0.96) and 1.00 (95% CI 0.72-1.00), respectively.

CONCLUSIONS

The clinical penetrance of VP in our family is approximately 40%. Many more subjects with VP are diagnosed in an asymptomatic phase than previously, and the acute attack is now an uncommon manifestation of VP. Plasma scanning is more sensitive than faecal porphyrin analysis, but neither is sufficiently sensitive for the detection of carrier status.

Plasma Fluorescence Scanning and Fecal Porphyrin Analysis for the Diagnosis of Variegate Porphyria: Precise Determination of Sensitivity and Specificity with Detection of Protoporphyrinogen Oxidase Mutations as a Reference Standard

Background: Variegate porphyria (VP) is the autosomal dominant disorder associated with deficiency of the enzyme protoporphyrinogen oxidase (PPOX). Plasma fluorescence scanning has been reported to be a more sensitive test for VP than traditional fecal chromatography. Previous comparisons of these techniques predated identification of the PPOX gene. We assessed these techniques in a large group of patients characterized for VP at the DNA level.

Methods: We evaluated all patients for whom the genotype and a plasma scan or fecal porphyrin result were available. Mutations were detected by restriction digest analysis. Plasma fluorescence scanning was conducted according to published methods. Fecal porphyrins were identified and quantified by thin-layer chromatography.

Results: Plasma fluorescence scanning was assessed in 679 patients (205 with VP who were carriers of a PPOX mutation, either with disease symptoms or asymptomatic) and fecal analysis in 473 (190 with VP). Sensitivity and specificity of both tests were higher in adults than in children and higher for adults with disease symptoms than for asymptomatic carriers. In a direct comparison in 168 adults (73 with VP), plasma scanning was significantly more sensitive than fecal porphyrin analysis [sensitivity, 0.96 (95% confidence interval, 0.89–0.99) vs 0.77 (0.66–0.85)]. Fecal coproporphyrin [area under the curve, 0.87 (0.83–0.90)] was a better predictor of VP than protoporphyrin [0.80 (0.76–0.84)].

Conclusions: Plasma scanning is a more sensitive and specific test for VP than fecal porphyrin analysis. Neither test is sensitive in children, and both are less sensitive in asymptomatic carriers than in symptomatic cases. DNA analysis therefore remains the preferred method for the identification of carriers, particularly in children.

Administration of oral activated charcoal in variegate porphyria results in a paradoxical clinical and biochemical deterioration

BACKGROUND

Porphyrinogens are the obligate intracellular precursors of haem. These compounds are, however, unstable and are easily oxidized to the corresponding porphyrins, which are the form in which they are usually measured in the laboratory. A substantial enterohepatic cycling of porphyrins has been shown. Administration of oral activated charcoal, by interrupting this cycle, may reduce plasma and urine porphyrin levels in patients with some forms of porphyria. The effect of charcoal in subjects with variegate porphyria (VP) has not been reported.

OBJECTIVES

To determine the clinical and biochemical effects of the administration of oral activated charcoal in patients with VP.

METHODS

Oral activated charcoal was administered to eight subjects with VP. Clinical activity was assessed by skin lesion counts fortnightly for 6 weeks, 6 weeks after cessation of therapy, and during a subsequent 6-week control period during which no charcoal was taken. Urine and plasma porphyrins and urine precursors were measured by standard techniques.

RESULTS

Treatment resulted in a significant increase in skin disease, urine and plasma porphyrins.

CONCLUSIONS

Oral charcoal administration results in a paradoxical aggravation of VP, suggesting a complex and as yet undefined interaction of hepatic porphyrin metabolism and bowel porphyrin reabsorption. Oral sorbents should not be prescribed to subjects with VP.

Porphyria cutanea tarda: the etiological importance of mutations in the HFE gene and viral infection is population-dependent

A number of factors, including increased iron stores and alcohol consumption, are known to be associated with the development of porphyria cutanea tarda (PCT) in susceptible individuals. Recent reports have described a significant association between inheritance of the C282Y and H63D mutations in the HFE gene, associated with genetic hemochromatosis (GH) and PCT. A strong association between hepatitis C virus infection and PCT has also been demonstrated, while case reports record a link between human immunodeficiency virus (HIV) and PCT. We have investigated the frequency of these factors in a racially-mixed population of patients with PCT in Cape Town, South Africa. 57 patients with PCT drawn from three ethnic groups were screened for the presence of the C282Y and H63D mutations linked to GH, and the prevalences were compared with corresponding healthy control populations. The seroprevalence of markers for HCV, hepatitis B (HBV) and HIV infection were examined in 28 of these. In the control populations, we found that both the C282Y and H63D mutations are highly prevalent in South Africans of European origin. In a population of mixed or Asian origin, the C282Y mutation is very rare whereas the H63D mutation is common. Neither mutation was encountered in any African subject. Both mutations are associated with PCT, but the association is dependent on the ethnic origins of the population to which the patient belongs. In contrast to other studies, HCV infection is numerically unimportant in PCT in our patients. HIV infection is increasingly encountered in our patients with PCT, but the strength of the association cannot be determined in view of the high background prevalence of HIV infection in some sectors of the South African population. The contribution of specific risk factors may be heavily dependent on the population from which patients are drawn, and care should be taken in extrapolating from observations in one racial or geographic population to any other.

Treatment of acute porphyria

Haem preparations are now available for the specific treatment of attacks of acute porphyria. This review focuses on their use in this uncommon but life-threatening medical emergency.

Identification of the first variegate porphyria mutation in an indigenous black South African and further evidence for heterogeneity in variegate porphyria

Variegate porphyria is an autosomal dominant disorder of haem metabolism resulting from reduced levels of the penultimate enzyme in the pathway, protoporphyrinogen oxidase. Here we investigate the molecular basis of variegate porphyria in four non-R59W South African families. We report the identification of the first mutation in the protoporphyrinogen oxidase gene in a black South African individual (V290M). In addition, we document three further mutations, a missense mutation (L15F), a deletion followed by a substitution [c769delG;770T > A], and a nonsense mutation (Q375X), in individuals of European or mixed ancestry. Our data provide further evidence of genetic heterogeneity in South Africa.

Identification and characterisation of a deletion (537delAT) in the protoporphyrinogen oxidase gene in a South African variegate porphyria family

Variegate porphyria is an autosomal dominant disorder of haem metabolism resulting from a partial decrease in protoporphyrinogen oxidase activity. Variegate porphyria is highly prevalent in South Africa, the result of a founder effect now confirmed genetically as a single point mutation (R59W) which has been described in nearly all South African variegate porphyria patients studied. Only two other mutations (H20P, R168C) have been reported in South Africa. We utilised simultaneous, single-stranded conformational polymorphism and heteroduplex analysis, and direct sequencing to identify a further mutation; a 2 bp deletion in exon 6 which results in a premature stop codon 11 codons downstream from the mutation and is the first reported deletion in the protoporphyrinogen oxidase gene in a South African family. The familial segregation of this mutation strongly suggests that it is the disease causing mutation for variegate porphyria in this family. This further evidence for allelic heterogeneity limits the utility of tests for the R59W mutation in the diagnosis of variegate porphyria in South Africa.

Homozygous variegate porphyria in South Africa: genotypic analysis in two cases

Variegate porphyria is an autosomal dominant disorder of heme metabolism which results from decreased activity of the enzyme protoporphyrinogen oxidase. Clinically, the disease manifests postpubertally and is characterized by photocutaneous sensitivity and/or acute neurovisceral crises. However, in homozygous variegate porphyria, onset of the disease usually occurs in infancy with severe skin manifestations. The molecular basis of variegate porphyria in two severely affected probands in two South African families is described. Mutation detection included combined SSCP-heteroduplex analysis followed by direct sequencing. The unrelated probands both had the common R59W mutation while the other lesion was Y348C or R138P (both novel mutations), causing homozygous variegate porphyria.

Variegate porphyria

Variegate porphyria is an autosomal dominant inherited trait resulting in decreased activity of protoporphyrinogen oxidase. It is characterized clinically by photosensitive skin disease and a propensity to acute neurovisceral crises. The disease is found worldwide but has an exceptionally high frequency in South Africa. The gene for human protoporphyrinogen oxidase has been identified and sequenced, and several mutations in the protoporphyrinogen oxidase gene sequence have been identified. In South Africa, fewer patients now present with acute attacks, leaving a greater proportion with skin disease or asymptomatic disease. Acute attacks of variegate porphyria appear to be less easily provoked and to be milder than those associated with acute intermittent porphyria.

Identification of two novel mutations in the hydroxymethylbilane synthase gene in three patients from two unrelated families with acute intermittent porphyria

We have screened the hydroxymethylbilane synthase cDNAs of 3 patients from 2 families suffering from acute intermittent porphyria (AIP) from Scotland and South Africa using heteroduplex and chemical cleavage of mismatch analyses. Direct sequencing was used to characterise the mutations. The two novel mutations identified were a missense mutation at nucleotide position 64 in exon 3 (R22C) and a single base-pair deletion in exon 15. These mutations are predicted to affect the normal function of the enzyme and, therefore, are expected to be the primary cause of disease in these patients.

Acute intermittent porphyria: the in vitro expression of mutant hydroxymethylbilane synthase

Acute intermittent porphyria (AIP) is an inborn error of haem biosynthesis caused by a variety of mutations in the gene coding for hydroxymethylbilane synthase (HMB-S). The entire coding sequence of this gene, from each of three South African AIP patients, was therefore screened for mutations using chemical cleavage mismatch (CCM) analysis and any changes detected characterized by DNA sequencing. Three single base changes were identified; a G77 to A in exon 3, a C346 to T in exon 8 and a G518 to A in exon 10. These missense mutations, previously reported to be present in other populations, are known to be responsible for the structurally deleterious amino acid replacements R26H, R116W and R173Q, respectively. The in vitro expression of the enzymes containing these mutations and the subsequent measurement of their specific activities revealed a reduction to approximately 4% of normal activity.

Variegate porphyria in South Africa, 1688-1996--new developments in an old disease

Variegate porphyria, an autosomal dominant inherited trait resulting in decreased activity of protoporphyrinogen oxidase, the penultimate haem biosynthetic enzyme, is characterised clinically by photosensitive skin disease and a propensity to acute neurovisceral crises. The disease has an exceptionally high frequency in South Africa, owing to a founder effect. The specific mutation in the protoporphyrinogen oxidase gene sequence which represents this founder gene has been identified. Genetic diagnosis is therefore now possible in families in whom the gene defect is known. However, the exact nature and degree of activity of the porphyria can only be determined by detailed quantitative biochemical analysis of excreted porphyrins. The relative contributions of the acute attack and the skin disease to the total disease burden of patients with variegate porphyria is not static, and in South Africa there have been significant changes over the past 25 years, with fewer patients presenting with acute attacks, leaving a greater proportion to present with skin disease or to remain asymptomatic with the diagnosis being made in the laboratory. The most common precipitating cause of the acute attack of VP is administration of porphyrinogenic drugs. Specific suppression of haem synthesis with intravenous haem arginate is the most useful treatment of a moderate or severe acute attack. Although cutaneous lesions are limited to the sun-exposed areas, management of the skin disease of VP remains inadequate.

Drugs in the acute porphyrias--toxicogenetic diseases

The acute Porphyrias are examples of toxico-genetic diseases and diseases genetically acquired, which show an idiosyncratic reaction to certain chemicals and drugs. Porphyrics are at risk of developing an acute attack if exposed to various precipitating factors of which drugs are the most common factor. This paper presents lists of drugs complied into those hazardous for patients with acute porphyria and those thought to be safe.

A R59W mutation in human protoporphyrinogen oxidase results in decreased enzyme activity and is prevalent in South Africans with variegate porphyria

Variegate porphyria (VP), a low-penetrant autosomal dominant inherited disorder of haem metabolism, is characterised by photosensitivity (Fig. 1) and a propensity to develop acute neuropsychiatric attacks with abdominal pain, vomiting, constipation, tachycardia, hypertension, psychiatric symptoms and, in the worst cases, quadriplegia. Acute attacks, often precipitated by inappropriate drug therapy, are potentially fatal. While earlier workers thought the distal haem biosynthetic enzyme ferrochelatase may be involved in the genesis of VP, it was shown in the early 1980's, and is now accepted, that VP is associated with decreased protoporphyrinogen oxidase activity (PPO) (E.C.1.3.3.4). VP prevalence is much higher in South Africa than elsewhere; probably due to a founder effect with patients descending from a 17th century Dutch immigrant. PPO cDNAs from Bacillus subtilis, Myxococcus xanthus, human placenta and mouse liver have been cloned, sequenced and expressed. Human and mouse cDNAs consist of open reading frames 1431 nucleotides long, encoding a 477 amino acid protein. The human PPO gene contains thirteen exons, spanning approximately 4.5 kb. We have identified a C to T transition in codon 59 (in exon 3) resulting in an arginine to tryptophan substitution (R59W). A protein expressed from an in vitro-mutagenized PPO construct exhibits substantially less activity than the wild type. The R59W mutation was present in 43 of 45 patients with VP from 26 of 27 South African families investigated, but not in 34 unaffected relatives or 9 unrelated British patients with PPO deficiency. Since at least one of these families is descended from the founder of South African VP, this defect may represent the founder gene defect associated causally with VP in South Africa.

Mapping of the variegate porphyria (VP) gene: contradictory evidence for linkage between VP and microsatellite markers at chromosome 14q32

The gene for variegate porphyria (VP), an autosomal dominant disease with a high prevalance in South Africa, evidently due to a founder effect, was previously mapped to chromosome 14q32. In the current study this localization was evaluated by linkage and haplotype analyses using microsatellite markers spanning a region of more than 20 cM on chromosome 14q32. In many recent studies linkage disequilibrium between disease and marker loci has been utilized to map genes in founder populations, but we could not find any association between VP and the markers used in this study. Our data suggest that the allocation of VP to chromosome 14q32 may be incorrect.

Detection of four mutations in six unrelated South African patients with acute intermittent porphyria

We have screened the hydroxymethylbilane synthase cDNA from six South African patients with acute intermittent porphyria, using a combination of chemical cleavage mismatch analysis and direct sequencing of asymmetrically amplified PCR products. Four mutations were detected, a novel T insertion (771insT) and three missense mutations (R26H, R116W and R173Q). The 771insT mutation produces a stop codon, thirty-three codons downstream and a loss of approximately 20% of the protein is predicted. The R116W mutation, which was found to have a high prevalence in the Dutch population, was detected in three unrelated South African patients.

Inhibition of mammalian protoporphyrinogen oxidase by acifluorfen

We have studied the kinetics of the inhibition of mitochondrial protoporphyrinogen oxidase (PPO) from liver and placenta of 3 mammalian species by the diphenyl ether herbicide acifluorfen (AF). AF competitively inhibited PPO from human liver and placenta, mouse liver and pig placenta with respect to its substrate protoporphyrinogen. In contrast, mixed-type inhibition was shown for pig liver. The differing results shown in pig liver may point to structural differences in PPO derived from different species and tissues. We have also compared the effects of AF on the function of PPO in human lymphoblasts from normal subjects and those with variegate porphyria, an inherited disorder of PPO. Competitive inhibition was shown for both and there were no significant differences in the values of Ks or Ki.

Hepatoerythropoietic porphyria precipitated by viral hepatitis

Porphyria cutanea tarda (PCT), the condition resulting from a deficiency of hepatic uroporphyrinogen decarboxylase activity, is the commonest form of porphyria. Both acquired and familial form exist and are commonly associated in adults with liver disease and hepatic iron overload. The condition is extremely rare in children; most cases of childhood PCT are familial and some particularly severe cases have been shown to have a hepatoerythropoietic porphyria or homozygous uroporphyrinogen decarboxylase deficiency. A case is described of hepatoerythropoietic porphyria in which the disease was first precipitated at the age of two by a coincidental hepatitis A infection and improved as the hepatitis cleared. This paper reviews the evidence that viral hepatitis may precipitate overt PCT in children in a manner analogous to the precipitation of PCT in adults by alcohol associated liver disease.

Homozygous variegate porphyria: an evolving clinical syndrome

Variegate porphyria is one of the most frequently encountered genetic conditions in South Africa. It is inherited as an autosomal dominant disease and in excess of 300 heterozygous cases have been studied by the Cape Town unit. Despite this, the homozygous condition has not previously been encountered in South Africa. We report two cases of homozygous variegate porphyria, one of whom represents the first South African case. We delineate a syndrome principally characterized by growth retardation, developmental delay, epileptic seizures, photosensitivity and an abnormal porphyrin excretion pattern. In addition we describe, in one case, two features not previously reported: skin disease in areas unexposed to light and a severe sensory neuropathy which may account at least in part for the hand deformities of this disorder.

The effect of oral activated charcoal on the course of congenital erythropoietic porphyria

The administration of oral activated charcoal to two patients with congenital erythropoietic porphyria has previously been reported to result in a marked reduction in plasma and urinary porphyrin concentrations and in one case, clinical remission. We describe an additional case in which the use of charcoal was associated with an apparent exacerbation of the biochemical activity of the disease following an initial period of remission. This result is unexpected, and currently unexplained. We conclude that charcoal therapy in porphyria may not be without risk, and should be used with caution.

Safety and efficacy of interferon alpha-2b following prednisone withdrawal in the treatment of chronic viral hepatitis B. A case-controlled, randomised study

The therapeutic effects of interferon alpha-2b (Intron A; Scherag) in patients with chronic active hepatitis caused by hepatitis B virus (HBV) were assessed in a randomised, case-controlled clinical trial conducted between January 1988 and June 1990. Treatment involved a short course of prednisone followed by interferon alpha-2b, initially 10 million U by subcutaneous injection, 3 times a week for 16 weeks. All patients were symptomatic, were known to have had hepatitis B surface antigen and hepatitis B e antigen (HBeAg) in their blood for at least 6 months, and had elevated serum aminotransferase activities with histological evidence of chronic active hepatitis. Patients with carcinoma, renal or haematological abnormalities or decompensated cirrhosis were excluded. In 6 of 10 patients randomised to receive interferon and 1 of 10 controls, HBeAg and HBV DNA were cleared from the blood during the 12-month study period (P < 0.05). An indeterminate response with clearance of HBV DNA but persistence of HBeAg was noted in 1 patient receiving interferon. Serum aminotransferase levels decreased only in those patients who had responded to treatment, but this did not reach statistical significance for the group as a whole. Histological studies, where available, showed decreased hepatic periportal necrosis in patients who underwent treatment. Two patients relapsed to HBeAg-positive status 2 months after their initial seroconversion; 1 became clear again during a repeat course of interferon. Side-effects of treatment were common and included fever, malaise, myalgias and myelosuppression. One patient developed hypothyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired hypoprothrombinaemia and lupus anticoagulant: response to steroid therapy

An iliac crest bone marrow aspiration in a 24-year-old man was followed by severe haemorrhage into the iliopsoas muscle. A lupus anticoagulant and severe hypoprothrombinaemia, as well as clinical and laboratory pointers to suggest the presence of a systemic lupus erythematosus-like syndrome, were demonstrated. Therapy with prednisone was commenced following recurrent severe epistaxis. His prothrombin time, activated partial thromboplastin time and prothrombin activity improved promptly and his bleeding ceased. The lupus anticoagulant is commonly encountered in the laboratory, but acquired hypoprothrombinaemia is extremely rare. The condition is reviewed and its treatment discussed.

Propofol as an i.v. anaesthetic induction agent in variegate porphyria

The choice of an i.v. anaesthetic induction poses problems for the anaesthetist confronted with a patient with one of the acute porphyrias. We undertook a prospective clinical trial in 13 variegate porphyric subjects using propofol as an anaesthetic induction agent. Urinary porphyrin precursors and porphyrins were measured before operation and 1-5 days after operation. Stool and plasma porphyrin concentrations were measured over the same period. Comparison of these data in the porphyric patients and in 21 control subjects over the trial period revealed no significant change in porphyrin or porphyrin precursor output after operation. Urinary porphyrin precursor concentrations did not exceed the limits established for variegate porphyric patients in remission, and there were no changes in the stool and plasma porphyrin profiles or any symptoms of an acute porphyric attack. We conclude that propofol did not appear to be porphyrinogenic when used for the induction of anaesthesia in 13 patients with variegate porphyria.

Primary biliary cirrhosis. A retrospective survey at Groote Schuur Hospital, Cape Town

Primary biliary cirrhosis (PBC) or chronic non-suppurative destructive cholangiohepatitis is rare in southern Africa. Eight patients with this diagnosis were identified and fully investigated at Groote Schuur Hospital between 1980 and 1988. Seven patients were female, all were white or coloured, and their ages ranged from 49 years to 80 years. All patients presented with a history of malaise, fatigue, night sweats and pruritus, which had been present for 3 months--12 years before diagnosis of PBC. Initial misdiagnosis had resulted in unnecessary invasive investigations including laparotomies. Signs of chronic liver disease, such as xantholasmas, evidence of pruritus, the sicca syndrome or hepatomegaly, were invariably present. Marked elevation of serum alkaline phosphatase level and IgM were present in all cases. Antimitochondrial antibodies were positive in significant titre in 7 of the 8 patients. Liver biopsies demonstrated stage II-III disease in all patients. Therapy was chiefly supportive and symptomatic although most patients received immunosuppressive agents. Despite the late presentation, the subsequent course was similar to that seen elsewhere where patients are recognised earlier.