Congenital erythropoietic porphyria. I. Case report, special studies and therapy

Developmental defects of enamel and dentine: challenges for basic science research and clinical management

Abnormalities of enamel and dentine are caused by a variety of interacting factors ranging from genetic defects to environmental insults. The genetic changes associated with some types of enamel and dentine defects have been mapped, and many environmental influences, including medical illnesses that can damage enamel and dentine have been identified. Developmental enamel defects may present as enamel hypoplasia or hypomineralization while dentine defects frequently demonstrate aberrant calcifications and abnormalities of the dentine-pulp complex. Clinically, developmental enamel defects often present with problems of discolouration and aesthetics, tooth sensitivity, and susceptibility to caries, wear and erosion. In contrast, dentine defects are a risk for endodontic complications resulting from dentine hypomineralization and pulpal abnormalities. The main goals of managing developmental abnormalities of enamel and dentine are early diagnosis and improvement of appearance and function by preserving the dentition and preventing complications. However, despite major advances in scientific knowledge regarding the causes of enamel and dentine defects, further research is required in order to translate the knowledge gained in the basic sciences research to accurate clinical diagnosis and successful treatment of the defects.

Congenital erythropoietic porphyria: characterization of murine models of the severe common (C73R/C73R) and later-onset genotypes

Congenital erythropoietic porphyria (CEP) is an autosomal recessive disorder due to the deficient activity of uroporphyrinogen III synthase (UROS). Knock-in mouse models were generated for the common, hematologically severe human genotype, C73R/C73R, and milder genotypes (C73R/V99L and V99L/V99L). The specific activities of the UROS enzyme in the livers and erythrocytes of these mice averaged approximately 1.2%, 11% and 19% of normal, respectively. C73R/C73R mice that survived fetal life to weaning age (~12%) had a severe microcytic hypochromic anemia (hemoglobin 7.9 g/dL, mean cellular volume 26.6 fL, mean cellular hemoglobin content 27.4 g/dL, red cell distribution width 37.7%, reticulocytes 19%) and massively accumulated isomer I porphyrins (95, 183 and 44 μmol/L in erythrocytes, spleen and liver, respectively), but a nearly normal lifespan. In adult C73R/C73R mice, spleen and liver weights were 8.2- and 1.5-fold increased, respectively. C73R/V99L mice were mildly anemic (hemoglobin was 14.0 g/dL and mean cellular hemoglobin was 13.3), with minimally accumulated porphyrins (0.10, 5.54 and 0.58 μmol/L in erythrocytes, spleen and liver, respectively), whereas adult V99L/V99L mice were normal. Of note, even the mildest genotype, V99L/V99L, exhibited porphyria in utero, which disappeared by 2 months of age. These severe and mild mouse models inform therapeutic interventions and permit further investigation of the porphyrin-induced hematopathology, which leads to photo-induced cutaneous lesions. Of significance for therapeutic intervention, these mouse models suggest that only 11% of wild-type activity might be needed to reverse the pathology in CEP patients.

Neonatal Hemolytic Anemia Due to Inherited Harderoporphyria: Clinical Characteristics and Molecular Basis

Porphyrias, a group of inborn errors of heme synthesis, are classified as hepatic or erythropoietic according to clinical data and the main site of expression of the specific enzymatic defect. Hereditary coproporphyria (HC) is an acute hepatic porphyria with autosomal dominant inheritance caused by deficient activity of coproporphyrinogen III oxidase (COX). Typical clinical manifestations of the disease are acute attacks of neurological dysfunction; skin photosensitivity may also be present. We report a variant form of HC characterized by a unifying syndrome in which hematologic disorders predominate: harderoporphyria. Harderoporphyric patients exhibit jaundice, severe chronic hemolytic anemia of early onset associated with hepatosplenomegaly, and skin photosensitivity. Neither abdominal pain nor neuropsychiatric symptoms are observed. COX activity is markedly decreased. In a first harderoporphyric family, with three affected siblings, a homozygous K404E mutation has been previously characterized. In the present study, molecular investigations in a second family with neonatal hemolytic anemia and harderoporphyria revealed two heterozygous point mutations in the COX gene. One allele bore the missense mutation K404E previously described. The second allele bore an A→G transition at the third position of the donor splice site in intron 6. This new COX gene mutation resulted in exon 6 skipping and the absence of functional protein production. In contrast with other COX gene defects that produce the classical hepatic porphyria presentation, our data suggest that the K404E substitution (either in the homozygous or compound heterozygous state associated with a mutation leading to the absence of functional mRNA or protein) is responsible for the specific hematologic clinical manifestations of harderoporphyria.

Congenital erythropoietic porphyria

Congenital erythropoietic porphyria is a rare autosomal-recessive disorder of the porphyrin metabolism caused by the homozygous defect of uroporphyrinogen III cosynthase. High amounts of uroporphyrin I accumulate in all cells and tissues, reflected by an increased erythrocyte porphyrin concentration and excretion of high porphyrin amounts in urine and feces. Dermal deposits of uroporphyrin frequently induce a dramatic phototoxic oxygen-dependent skin damage with extensive ulcerations and mutilations. Splenomegaly and hemolytic anemia are typical internal symptoms. Skeletal changes such as osteolysis and calcifications are frequent. To date 130 cases of congenital erythropoietic porphyria have been published and are summarized here. Splenectomy, erythrocyte transfusions, and bone marrow transplantation have shown some beneficial effect. The best therapy is the avoidance of sunlight. In the two patients with congenital erythropoietic porphyria described here, oral administration of the oxygen quenchers ascorbic acid and alpha-tocopherol resulted in an improvement in the reduced hemoglobin and erythrocyte concentrations.

Correction of congenital erythropoietic porphyria by bone marrow transplantation

Congenital erythropoietic porphyria (Gunther disease) is a rare metabolic disorder caused by uroporphyrinogen III synthetase deficiency. We report the case of a 2-year-old girl with a severe form of this disease who received HLA-identical bone marrow transplantation from her heterozygous sister. Two transplantations were necessary to obtain full hematopoietic chimerism. Correction of the enzyme deficiency was confirmed by measuring erythrocyte uroporphyrinogen III synthetase activity. The patient's clinical condition improved dramatically, and she is well 1 year after the second transplantation, with no further treatment. Although long-term efficacy remains to be confirmed, we conclude that allogeneic bone marrow transplantation can cure patients with congenital erythropoietic porphyria.

Porphyria in childhood

Porphyria in childhood is an uncommon problem but the recognition of these disorders is vitally important for affected children. Of the cutaneous porphyrias, erythropoietic protoporphyria, congenital erythropoietic porphyria, hepatoerythropoietic porphyria, and the hereditary form of porphyria cutanea tarda (PCT) can present in infancy or childhood. This article focuses on the porphyrias that present in infants and children along with a brief discussion of pathogenesis, cutaneous histopathology, and genetics of these metabolic disorders.

Ocular involvement in two symptomatic congenital erythropoietic porphyria

Congenital erythropoietic porphyria (Gunther disease, CEP) is a rare autosomal recessive disorder of haeme biosynthesis. It is characterized by extreme photosensitivity and the excretion of large amounts of uroporphyrin I and coproporphyrin I in the urine and coproporphyrin I in the faeces. We have diagnosed two cases of congenital erythropoietic porphyria, who were first cousins once removed. They had recurrent skin bullae, scarring on the face and hands, hirsutism, discoloured fluorescent teeth, red urine, increased haemolysis and grossly increased excretion of porphyrin. Both children had blepharitis and their sclera gave pink fluorescence under long wave ultraviolet light, mainly in the interpalpebral fissures. All the features of our two patients, except the ocular lesions, conformed to cases of CEP reported in the literature. We have encountered no other reports on ocular lesions in CEP since first described by Chumbley in 1977.

Radiological features in congenital erythropoietic porphyria (Gunther's disease). Report of 3 cases

Gunther's disease or congenital erythropoietic porphyria is a rare and severe disorder comprising cutaneous and haemolytic symptoms. Photocutaneous lesions are responsible for scleroderma-like calcifications and deformities of the extremities visible on X-rays. Hemolytic manifestations lead to diffuse major osteopenia. Soft tissue calcifications of the fingers can be seen even in young patients. One case reported here is the first illustration of intracranial calcifications located on dura-mater and calvarium.

Uroporphyrinogen 3 cosynthetase in human congenital erythropoietic porphyria

Activity of the enzyme uroporphyrinogen III cosynthetase in hemolysates from five patients with congenital erythropoietic porphyria was much lower than the activity in control samples. The low cosynthetase activity in patients was not due to the presence of a free inhibitor or some competing enzymatic activity, because hemolysates from porphyric subjects did not interfere either with the cosynthetase activity of hemolysates from normal subjects or with cosynthetase prepared from hematopoietic mouse spleen. This partial deficiency of cosynthetase in congenital erythropoietic porphyria corresponds to that shown previously in the clinically similar erythropoietic porphyria of cattle and explains the overproduction of uroporphyrin I in the human disease.