No abstract

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.

OBJECTIVE -The normochromic normocytic anemia of erythropoietin (EPO) deficiency is recognized in advanced renal failure but not in early renal disease. The aim of this study was to determine whether anemia with EPO deficiency is found in type 1 diabetic patients with diabetic nephropathy in the absence of advanced renal failure and to compare them with patients with nondiabetic renal disease of similar severity. RESEARCH DESIGN AND METHODS-A total of 27 type 1 diabetic patients with diabetic nephropathy (DN), defined as having persistent proteinuria (mean 1,086 mg/day 190]), a serum creatinine Յ180 mol/l, and retinopathy, were compared with 26 nondiabetic patients with glomerulonephritis (GN) and persistent proteinuria (1,874 mg/day [349 -5,005]). The Hb concentration, red cell indexes, and serum EPO levels were measured, and other causes for the anemia were excluded. The EPO values were compared with a normal reference range obtained from nondiabetic patients with a microcytic anemia. The DN patients were tested for signs of diabetic peripheral and autonomic neuropathy.RESULTS -We found that 13 of the 27 DN patients were anemic (Hb 10.6 Ϯ 0.9 g/dl) in marked contrast to none of the GN patients (Hb 13.7 Ϯ 1.4 g/dl, P Ͻ 0.005). In the DN group, serum EPO concentrations failed to increase in response to anemia compared with the response seen in patients with microcytic anemia. Thus, the anemia of the DN group was associated with EPO deficiency. The anemic DN patients showed evidence of more severe proteinuria and diabetic neuropathy than the nonanemic DN patients.CONCLUSIONS -Anemia associated with EPO deficiency can occur early in DN before the onset of advanced renal failure, but does not normally occur in nondiabetic renal disease of similar severity. The pathogenesis requires elucidation. Diabetes Care 24:495-499, 2001

The porphyrias are disorders of haem biosynthesis which present with acute neurovisceral attacks or disorders of sun-exposed skin. Acute attacks occur mainly in adults and comprise severe abdominal pain, nausea, vomiting, autonomic disturbance, central nervous system involvement and peripheral motor neuropathy. Cutaneous porphyrias can be acute or chronic presenting at various ages. Timely diagnosis depends on clinical suspicion leading to referral of appropriate samples for screening by reliable biochemical methods. All samples should be protected from light. Investigation for an acute attack: • Porphobilinogen (PBG) quantitation in a random urine sample collected during symptoms. Urine concentration must be assessed by measuring creatinine, and a repeat requested if urine creatinine <2 mmol/L. • Urgent porphobilinogen testing should be available within 24 h of sample receipt at the local laboratory. Urine porphyrin excretion (TUP) should subsequently be measured on this urine. • Urine porphobilinogen should be measured using a validated quantitative ion-exchange resin-based method or LC-MS. • Increased urine porphobilinogen excretion requires confirmatory testing and clinical advice from the National Acute Porphyria Service. • Identification of individual acute porphyrias requires analysis of urine, plasma and faecal porphyrins. Investigation for cutaneous porphyria: • An EDTA blood sample for plasma porphyrin fluorescence emission spectroscopy and random urine sample for TUP. • Whole blood for porphyrin analysis is essential to identify protoporphyria. • Faeces need only be collected, if first-line tests are positive or if clinical symptoms persist. Investigation for latent porphyria or family history: • Contact a specialist porphyria laboratory for advice. Clinical, family details are usually required.

The National Acute Porphyria Service (NAPS) provides acute care support and clinical advice for patients in England with active acute porphyria requiring haem arginate treatment and patients with recurrent acute attacks.This audit examined the benefits and complications of regular haem arginate treatment started with prophylactic intent to reduce the frequency of recurrent acute attacks in a group of patients managed through NAPS. We included 22 patients (21 female and 1 male) and returned information on diagnosis, indications for prophylactic infusions, frequency and dose, analgesia, activity and employment and complications including thromboembolic disease and iron overload.The median age at presentation with porphyria was 21 years (range 9-44), with acute abdominal pain as the predominant symptom. Patients had a median of 12 (1-400) attacks before starting prophylaxis and had received a median of 52 (0-1,350) doses of haem arginate. The median age at starting prophylaxis was 28 years (13-58) with a median delay of 4 years (0.5-37) between presentation and prophylaxis. The frequency of prophylactic haem arginate varied from 1 to 8 per month, and 67% patients were documented as having a reduction in pain frequency on prophylaxis. Only one patient developed clinically significant iron overload and required iron chelation, but the number of venous access devices required varied from 1 to 15, with each device lasting a median of 1.2 years before requiring replacement. Six patients stopped haem arginate and in three this was because their symptoms had improved. Prophylactic haem arginate appears to be beneficial in patients with recurrent acute porphyria symptoms, but maintaining central venous access may prove challenging.

Some Type 1 diabetic patients with autonomic neuropathy present with an EPO-depleted anaemia, which responds to treatment with EPO. This observation supports the concept of autonomic neuropathy as a cause of anaemia with EPO depletion, although the role of established renal damage cannot be excluded.

Summary. Serum erythropoietin (Epo) values were estimated in samples from 125 patients with erythrocytosis to examine the specificity and sensitivity of reduced and raised values in the diagnosis of polycythaemia vera (PV) and secondary erythrocytosis (SE) respectively. Additionally, Epo values were estimated in samples from 49 patients with primary thrombocythaemia (PT) to determine whether Epo values were altered. We found high specificity (92%) and moderate sensitivity (64%) of low serum Epo values (below the reference range) in the diagnosis of PV, and also poor sensitivity (47%) of raised Epo values in the diagnosis of SE. Raised Epo values were not observed in PV patients with Hb > 14AE0 g/dl and were only observed in one PV patient with a relatively low Hb recovering from a gastro-intestinal haemorrhage. Raised Epo values occurred in some patients with apparent erythrocytosis (AE) and idiopathic erythrocytosis (IE), mainly at normal (rather than raised) Hb values (< 16 g/dl). Low Epo values occurred in a few AE, IE and SE patients at higher Hb values (> 16 g/dl). Low Epo values were less specific for PV when the Hb was raised, while raised Epo values were less specific for SE when the Hb was not raised. Approximately one third of patients with PT had a low (below the reference range) Epo value, this being associated with a high normal Hb (> 14 g/dl, P < 0AE001) and showing a trend towards association with absence of treatment. The high normal Hb values were in turn associated with an increased incidence of thrombotic events (P < 0AE05). These findings could influence the future investigation and management of PT patients.

Colour and pattern are key traits with important roles in camouflage, warning and attraction. Ideally, in order to begin to understand the evolution and ecology of colour in nature, it is important to identify and, where possible, fully characterise pigments using biochemical methods. The phylum Mollusca includes some of the most beautiful exemplars of biological pigmentation, with the vivid colours of sea shells particularly prized by collectors and scientists alike. Biochemical studies of molluscan shell colour were fairly common in the last century, but few of these studies have been confirmed using modern methods and very few shell pigments have been fully characterised. Here, we use modern chemical and multi-modal spectroscopic techniques to identify two porphyrin pigments and eumelanin in the shell of marine snails Clanculus pharaonius and C margaritarius. The same porphyrins were also identified in coloured foot tissue of both species. We use high performance liquid chromatography (HPLC) to show definitively that these porphyrins are uroporphyrin I and uroporphyrin III. Evidence from confocal microscopy analyses shows that the distribution of porphyrin pigments corresponds to the striking pink-red of C. pharaonius shells, as well as pink-red dots and lines on the early whorls of C. margaritarius and yellow-brown colour of later whorls. Additional HPLC results suggest that eumelanin is likely responsible for black spots. We refer to the two differently coloured porphyrin pigments as trochopuniceus (pink-red) and trochoxouthos (yellow-brown) in order to distinguish between them. Trochopuniceus and trochoxouthos were not found in the shell of a third species of the same superfamily, Calliostoma zizyphinum, despite its superficially similar colouration, suggesting that this species has different shell pigments. These findings have important implications for the study of colour and pattern in molluscs specifically, but in other taxa more generally, since this study shows that homology of visible colour cannot be assumed without identification of pigments.