Francesca Granata

Congenital erythropoietic porphyria linked to GATA1-R216W mutation: challenges for diagnosis.

Congenital erythropoietic porphyria (CEP) is a rare genetic disease that is characterized by a severe cutaneous photosensitivity causing unrecoverable deformities, chronic hemolytic anemia requiring blood transfusion program, and by fatal systemic complications. A correct and early diagnosis is required to develop a management plan that is appropriate to the patients needs. Recently only one case of X‐linked CEP had been reported, describing the trans‐acting GATA1‐R216W mutation. Here, we have characterized two novel X‐linked CEP patients, both with misleading hematological phenotypes that include dyserythropoietic anemia, thrombocytopenia, and hereditary persistence of fetal hemoglobin. We compare the previously reported case to ours and propose a diagnostic paradigm for this variant of CEP. Finally, a correlation between phenotype variability and the presence of modifier mutations in loci related to disease‐causing gene is described.

Advances in understanding the pathogenesis of congenital erythropoietic porphyria

Congenital erythropoietic porphyria (CEP) is a rare genetic disease resulting from the remarkable deficient activity of uroporphyrinogen III synthase, the fourth enzyme of the haem biosynthetic pathway. This enzyme defect results in overproduction of the non‐physiological and pathogenic porphyrin isomers, uroporphyrin I and coproporphyrin I. The predominant clinical characteristics of CEP include bullous cutaneous photosensitivity to visible light from early infancy, progressive photomutilation and chronic haemolytic anaemia. The severity of clinical manifestations is markedly heterogeneous among patients; and interdependence between disease severity and porphyrin amount in the tissues has been pointed out. A more pronounced endogenous production of porphyrins concomitant to activation of ALAS2, the first and rate‐limiting of the haem synthesis enzymes in erythroid cells, has also been reported. CEP is inherited as autosomal recessive or X‐linked trait due to mutations in UROS or GATA1 genes; however an involvement of other causative or modifier genes cannot be ruled out.

X-chromosomal inactivation directly influences the phenotypic manifestation of X-linked protoporphyria

X‐linked protoporphyria (XLP), a rare erythropoietic porphyria, results from terminal exon gain‐of‐function mutations in the ALAS2 gene causing increased ALAS2 activity and markedly increased erythrocyte protoporphyrin levels. Patients present with severe cutaneous photosensitivity and may develop liver dysfunction. XLP was originally reported as X‐linked dominant with 100% penetrance in males and females. We characterized 11 heterozygous females from six unrelated XLP families and show markedly varying phenotypic and biochemical heterogeneity, reflecting the degree of X‐chromsomal inactivation of the mutant gene. ALAS2 sequencing identified the specific mutation and confirmed heterozygosity among the females. Clinical history, plasma and erythrocyte protoporphyrin levels were determined. Methylation assays of the androgen receptor and zinc‐finger MYM type 3 short tandem repeat polymorphisms estimated each heterozygotes X‐chromosomal inactivation pattern. Heterozygotes with equal or increased skewing, favoring expression of the wild‐type allele had no clinical symptoms and only slightly increased erythrocyte protoporphyrin concentrations and/or frequency of protoporphyrin‐containing peripheral blood fluorocytes. When the wild‐type allele was preferentially inactivated, heterozygous females manifested the disease phenotype and had both higher erythrocyte protoporphyrin levels and circulating fluorocytes. These findings confirm that the previous dominant classification of XLP is inappropriate and genetically misleading, as the disorder is more appropriately designated XLP.

A puzzling mutation in congenital erythropoietic porphyria and an association with β-thalassaemia trait.

evidence base for PCA treatments. Furthermore, secondand third-line treatments were often not recorded, and when stated also varied greatly between individuals (see Table 1). Comments made by respondents confirm that PCAs are poorly understood and that clinicians face uncertainty in their diagnosis and management. Unfortunately, several dermatologists believed that PCAs are untreatable and histology is unhelpful. Trichologists generally offered supportive care and referred patients for diagnosis and treatment either to their GP or to a dermatologist. This is the first study to provide epidemiological data of PCA in U.K. general dermatology and trichology practice. These data highlight that PCAs are rare, and may even occur less frequently than reported, due to the possibility of nonresponse bias. Thus, gaining significant clinical experience in PCA management is limited outside the setting of a specialist hair clinic. Important investigations, such as diagnostic scalp biopsy, are often not performed despite recommendations to biopsy all cases of scarring alopecia. Our data suggest that PCAs are generally managed with difficulty. Prompt referrals to specialist hair clinics should be encouraged to enable the development of clinical expertise and promote recruitment into basic science and clinical research studies. Early diagnosis and effective management are essential to halt progression of these debilitating conditions, with further research urgently needed to identify effective treatment strategies. A national database of PCA cases would assist in gaining a better understanding of the natural history of each entity and help identify optimal management practices.

Molecular Basis of β-Thalassemia Intermedia in Erbil Province of Iraqi Kurdistan

Abstract β-Thalassemia intermedia (β-TI) is a clinical term describing a range of clinical phenotypes that are intermediate in severity between the carrier state and β-thalassemia major (β-TM). To characterize the molecular basis of β-TI in Erbil Province, Northern Iraq, 83 unrelated patients were investigated. Detection of β-globin gene mutations was carried out by reverse hybridization assay and direct gene sequencing. All patients were screened for the XmnI polymorphism by direct sequencing of HBG2 (Gγ promoter gene). Detection of α-globin gene deletions and triplication was carried out using the reverse hybridization assay. Four main molecular patterns were identified in association with the β-TI phenotype, namely: β+/β+ (38.5%), β+/β0 (21.6%), β0/β0 (31.3%), and β0/wild type (8.4%). IVS-I-6 (T > C) was the most frequently encountered mutation (55 alleles, 34.6%), followed by IVS-II-1 (G > A) and codon 8 (−AA); furthermore, we report for the first time from Iraq two β+ mutations, −87 (C > G) and 5′ untranslated region (5′UTR) +22 (G > A). The XmnI polymorphism was detected in 47.0% of patients, mainly in association with the β0/β0 genotype. The α-globin gene deletions were encountered in four cases, including one case with (– –FIL) double gene deletion, a report that is the first from our country. The α-globin gene triplication was detected in five of the seven heterozygous β-thalassemia (β-thal) patients. Similar to other Mediterranean countries, inheritance of mild β-globin mutations was the main molecular pattern underlying β-TI in our patients followed by the ameliorating effect of the XmnI polymorphism.

Molecular characterization, by digital PCR analysis of four HMBS gene mutations affecting the ubiquitous isoform of Porphobilinogen Deaminase (PBGD) in patients with Acute Intermittent Porphyria (AIP)

Genetic variants in promoters and alternative-splicing lesions require to be experimentally tested in order to validate them as causatives of a disease. The digital PCR (dPCR) approach, which is an alternative to the classical qPCR, is an innovative and a more sensitive method for the detection and quantification of nucleic acids. In the present study, we identified four HMBS gene mutations affecting the ubiquitous isoform of porphobilinogen deaminase (PBGD) and established a dPCR protocol which would be able to detect the different transcripts of this gene. With the application of this method, we were able to characterize the functional roles of these four genetic variants, demonstrating that all these mutations were causatives of the non-erythroid variant of the acute intermittent porphyria (AIP) disease.

Digital PCR (dPCR) analysis reveals that the homozygous c.315–48T>C variant in the FECH gene might cause erythropoietic protoporphyria (EPP)

Alterations in the ferrochelatase gene (FECH) are the basis of the phenotypic expressions in erythropoietic protoporphyria. The phenotype is due to the presence of a mutation in the FECH gene associated in trans to the c.315-48 T > C variant in the intron 3. The latter is able to increase the physiological quota of alternative splicing events in the intron 3. Other two variants in the FECH gene (c.1-252A > G and c.68-23C > T) have been found to be associated to the intron 3 variant in some populations and together, they constitute a haplotype (ACT/GTC), but eventually, their role in the alternative splicing event has never been elucidated. The absolute number of the aberrantly spliced FECH mRNA molecules and the absolute expression of the FECH gene were evaluated by digital PCR technique in a comprehensive cohort. The number of splicing events that rose in the presence of the c.315-48 T > C variant, both in the heterozygous and homozygous condition was reported for the first time. Also, the percentage of the inserted FECH mRNA increased, even doubled in the T/C cases, compared to T/T cases. The constant presence of variants in the promoter and intron 2 did not influence or modulate the aberrant splicing. The results of FECH gene expression suggested that the homozygosity for the c.315-48 T > C variant could be considered pathological. Thus, this study identified the homozygotes for the c.315-48 T > C variant as pathological. By extension, when the samples were categorised according to the haplotypes, the GTC haplotype in homozygosis was pathological.

Acute Intermittent Porphyria in a Child with Severe Neuropathy

Clinical presentation of acute intermittent porphyria before puberty is unusual. We diagnosed the non-erythroid variant form of this disease in a male child, who first presented, at the age of 6 years, with unexplained neurological symptoms and behavioural abnormalities. We also report the successful treatment, and the long-term clinical management.