Late-onset cutaneous porphyria in a patient heterozygous for a uroporphyrinogen III synthase gene mutation.

Deficiency of uroporphyrinogen III synthase (UROS) causes congenital erythropoietic porphyria (CEP). The disease, originating from the inheritance of mutations within the UROS gene, presents a recessive form of transmission. In a few patients, a late-onset CEP-like phenotype without UROS mutations appears to be associated with a myelodysplastic syndrome. We report a 60-year-old man with late-onset signs of cutaneous porphyria and accumulation in urine, plasma and faeces of type I porphyrin isomers characteristic of CEP. Analysis of DNA from peripheral leucocytes, skin and bone marrow aspirate showed that he was a heterozygous carrier of a Cys73Arg (c.217 T>C) mutation within UROS. Sequencing of cDNA from peripheral blood confirmed heterozygosity and expression of the normal allele. Measurement of UROS enzymatic activity in erythrocytes showed values ~70% of normal, indirectly indicating expression of the normal allele. Differently from other cases of late-onset uroporphyria, the patient did not present thrombocytopenia or any evidence of a myelodysplastic syndrome. Five years of clinical follow-up showed persistence of skin signs and increased excretion of porphyrins, independently of lifestyle factors or changes in medication regimes. We hypothesize acquired mosaicism (in the bone marrow) affecting the UROS gene. Thus, unstable cellular clones initiated overproduction of isomer I porphyrins leading to a CEP phenotype. This could be explained either by a clonal expansion of the porphyric (Cys73Arg) allele or by loss of function of the normal allele. Cellular turnover would facilitate release of uroporphyrins into circulation and subsequent skin lesions. This is the first case of a CEP heterozygous carrier presenting clinical manifestations.

Clinical experience of scoring criteria for Familial Hypercholesterolaemia (FH) genetic testing in Wales.

BACKGROUND/OBJECTIVE: Familial Hypercholesterolaemia (FH) is caused by mutations in genes of the Low Density Lipoprotein (LDL) receptor pathway. A definitive diagnosis of FH can be made by the demonstration of a pathogenic mutation. The Wales FH service has developed scoring criteria to guide selection of patients for DNA testing, for those referred to clinics with hypercholesterolaemia. The criteria are based on a modification of the Dutch Lipid Clinic scoring criteria and utilise a combination of lipid values, physical signs, personal and family history of premature cardiovascular disease. They are intended to provide clinical guidance and enable resources to be targeted in a cost effective manner. METHODS: 623 patients who presented to lipid clinics across Wales had DNA testing following application of these criteria. RESULTS: The proportion of patients with a pathogenic mutation ranged from 4% in those scoring 5 or less up to 85% in those scoring 15 or more. LDL-cholesterol was the strongest discriminatory factor. Scores gained from physical signs, family history, coronary heart disease, and triglycerides also showed a gradient in mutation pick-up rate according to the score. CONCLUSION: These criteria provide a useful tool to guide selection of patients for DNA testing when applied by health professionals who have clinical experience of FH.

X-linked dominant protoporphyria: a new porphyria.

X-linked dominant protoporphyria (XLDPP) was first reported in the genetics literature in 2008. It has a phenotype very similar to erythropoietic protoporphyria (EPP), but is distinguished from EPP by higher concentrations of erythrocyte protoporphyrin (of which a high proportion is zinc-chelated), its apparently higher incidence of liver disease, and an X-linked dominant pattern of inheritance. Dermatologists should understand how XLDPP differs from EPP, in order to advise newly diagnosed patients correctly about the genetic implications and the long-term management strategy. We present a case series of XLDPP to introduce this condition to the dermatology literature.

Role of genetic testing in the management of patients with inherited porphyria and their families.

The porphyrias are a group of mainly inherited metabolic conditions that result from partial deficiency of individual enzymes in the haem biosynthesis pathway. Clinical presentation is either with acute neurovisceral attacks, skin photosensitivity or both, and is due to overproduction of pathway intermediates. The primary diagnosis in the proband is based on biochemical testing of appropriate samples, preferably during or soon after onset of symptoms. The role of genetic testing in the autosomal dominant acute porphyrias (acute intermittent porphyria, hereditary coproporphyria and variegate porphyria) is to identify presymptomatic carriers of the family specific pathogenic mutation so that they can be counselled on how to minimize their risk of suffering an acute attack. At present the additional genetic factors that influence penetrance are not known, and all patients are treated as equally at risk. Genetic testing in the erythropoietic porphyrias (erythropoietic protoporphyria, congenital erythropoietic porphyria and X-linked dominant protoporphyria) is focused on predictive and preconceptual counselling, prenatal testing and genotype-phenotype correlation. Recent advances in analytical technology have resulted in increased sensitivity of mutation detection with success rates of greater than 90% for most of the genes. The ethical and consent issues are discussed. Current research into genetic factors that affect penetrance is likely to lead to a more refined approach to counselling for presymptomatic gene carriers.

A management algorithm for congenital erythropoietic porphyria derived from a study of 29 cases.

BACKGROUND: Congenital erythropoietic porphyria (CEP) is an autosomal recessive photomutilating porphyria with onset usually in childhood, where haematological complications determine prognosis. Due to its extreme rarity and clinical heterogeneity, management decisions in CEP are often difficult. OBJECTIVES: To develop a management algorithm for patients with CEP based on data from carefully characterized historical cases. METHODS: A single investigator collated data related to treatments and their outcomes in 29 patients with CEP from the U.K., France, Germany and Switzerland. RESULTS: Six children were treated with bone marrow transplantation (BMT); five have remained symptomatically cured up to 11.5 years post-transplantation. Treatments such as oral charcoal, splenectomy and chronic hypertransfusion were either of no benefit or were associated with complications and negative impact on health-related quality of life. Lack of consistent genotype-phenotype correlation meant that this could not be used to predict disease prognosis. The main poor prognostic factors were early age of disease onset and severity of haematological manifestations. CONCLUSIONS: A management algorithm is proposed where every patient, irrespective of disease severity at presentation, should receive a comprehensive, multidisciplinary clinical assessment and should then be reviewed at intervals based on their predicted prognosis, and the rate of onset of complications. A BMT should be considered in those with progressive, symptomatic haemolytic anaemia and/or thrombocytopenia. Uroporphyrinogen III synthase genotypes associated with poor prognosis would additionally justify consideration for a BMT. Rigorous photoprotection of the skin and eyes from visible light is essential in all patients.

Congenital erythropoietic porphyria: a single-observer clinical study of 29 cases.

BACKGROUND: Congenital erythropoietic porphyria (CEP) is an autosomal recessive cutaneous porphyria caused by decreased activity of uroporphyrinogen III synthase (UROS). Its predominant characteristics include bullous cutaneous photosensitivity to visible light from early infancy, progressive photomutilation and chronic haemolytic anaemia. Due to its rarity and genetic heterogeneity, clinical phenotypes are unclear and its impact on health-related quality of life (HRQoL) has not been previously assessed. OBJECTIVES: To define comprehensively CEP phenotypes and assess their impact on HRQoL, and to correlate these factors with laboratory parameters. METHODS: A single observer assessed patients with CEP from four European countries. RESULTS: Twenty-seven unrelated patients with CEP, aged between 7.6 and 65 years, participated in the study. The patients came from the U.K. (17), France (4), Switzerland (4) and Germany (2). Additional data were obtained for two deceased patients. Newly characterized features of CEP include acute-onset cutaneous and noncutaneous symptoms immediately following sunlight exposure, and pink erythematous facial papules. There was a lack of consistent genotype-phenotype correlation in CEP. The main poor prognostic factors in CEP are the early age of disease onset and haematological complications. CONCLUSIONS: CEP is a multisystem disease; cutaneous, ocular, oral and skeletal manifestations also contribute to disease severity and impact on HRQoL, in addition to the haematological complications. The rarity of the disease can lead to delayed diagnosis. The lack of consistent genotype-phenotype correlation in CEP suggests a contribution to phenotype from other factors, such as environment, patients' photoprotective behaviour and genes other than UROS. There is currently an unmet need for multidisciplinary management of patients with CEP.

Molecular epidemiology of erythropoietic protoporphyria in the U.K.

BACKGROUND: Erythropoietic protoporphyria (EPP) is a cutaneous porphyria caused by mutations in the ferrochelatase (FECH) or, less frequently, the delta-aminolaevulinate synthase 2 (ALAS2) gene. Predictive genetic counselling requires accurate molecular diagnosis and knowledge of patterns of inheritance. OBJECTIVES: To investigate the molecular epidemiology of EPP in the U.K. METHODS: DNA samples from 191 unrelated patients resident in the U.K. were analysed for mutations in the FECH and ALAS2 genes and for the FECH IVS3-48 dimorphism. RESULTS: Mutations were identified in 179 (94%) patients. Most (169; 94%) had a FECH mutation on one allele and were classified as having pseudodominant EPP (psdEPP); seven (4%) patients had FECH mutations on both alleles (autosomal recessive EPP) and three (2%) patients had ALAS2 mutations (X-linked dominant protoporphyria). The FECH IVS3-48C allele was strongly associated with psdEPP and with the absence of mutations at the FECH or ALAS2 loci. Fifty-six FECH mutations were identified, 19 being previously unreported. Missense mutations were predominant in autosomal recessive EPP (82%) but not in psdEPP (32%). One mutation (c.314 + 2T>G) was present in 41 (24%) of EPP families, most of whom appeared to be descended from a common ancestor resident in the north of England. CONCLUSIONS: These data define the prevalence and molecular epidemiology of each type of EPP in the U.K.

The molecular genetics of erythropoietic protoporphyria.

Erythropoietic protoporphyria (EPP) is a syndrome in which accumulation of protoporphyrin IX in erythroid cells, plasma, skin and liver leads to acute photosensitivity and, in about 2% of patients, liver disease. More than 95% of unrelated patients have ferrochelatase (FECH) deficiency (MIM 177000) while about 2% have X-linked dominant protoporphyria (XLDPP) (MIM 300752) caused by gain-of-function mutations in the ALAS2 gene. Most FECH-deficient patients are compound heterozygotes for a hypomorphic allele (FECH IVS3-48C) and a deleterious FECH mutation that together lower FECH activity to around 30% of normal. The frequency of the IVS3-48C allele varies between populations, ranging from less than 1% to 45%. About 4% of unrelated FECH-deficient patients are compound heterozygotes or homozygotes for rare FECH mutations and have lower enzyme activities. Acquired somatic mutation of FECH secondary to myeloid disease may rarely cause EPP. The risk of liver disease is increased in XLDPP and in FECH-deficient patients who are hetero- or homoallelic for rare FECH mutations. Inherited FECH-deficient EPP is an autosomal recessive disorder with some families showing pseudodominant inheritance; the proportion of such families being determined by the population frequency of the IVS3-48C allele.

Late presentation of erythropoietic protoporphyria: case report and genetic analysis of family members.

Erythropoietic protoporphyria (EPP) is an inherited disorder of haem biosynthesis caused by decreased activity of the enzyme ferrochelatase (FECH), which catalyses the insertion of iron into protoporphyrin, the last step in haem biosynthesis. Development of clinically overt EPP usually requires inheritance of a severe FECH mutation trans to a low-expression FECH variant (FECH IVS3-48C), which is present in 13% of the U.K. population. Reduced FECH activity leads to accumulation of protoporphyrin in various tissues. An excess amount of free protoporphyrin in the skin causes photosensitivity. EPP usually presents in early childhood or infancy, with painful burning and pruritus within minutes of light exposure. Onset of symptoms in adults is rare and often associated with acquired somatic mutation of the FECH gene secondary to haematological malignancy. Here we describe a patient with EPP, in whom the presenting clinical symptom, night-time itch, did not appear until middle age and who had an asymptomatic sister with the same FECH genotype.

Allogeneic bone marrow transplantation in a 7-year-old girl with congenital erythropoietic porphyria: a treatment dilemma.

Congenital erythropoietic porphyria (CEP, Günther's disease) has a very variable phenotype. In the more severely affected, bone marrow transplantation (BMT) is potentially curative, but is not without risks. We describe a 7-year-old girl with CEP characterized by severe photosensitivity but only mild anaemia, in whom the difficult decision to proceed with allogeneic BMT was made after discussion in a multidisciplinary team. She has shown successful engraftment, accompanied by biochemical and clinical resolution of her metabolic disease. She remains well 3 years later, the oldest patient with CEP receiving BMT to survive beyond 12 months. However, she has experienced significant morbidity including florid cutaneous graft-versus-host disease with postinflammatory hypopigmentation. Her case is important in highlighting the delay in diagnosis not uncommon in this condition and the complex decision-making process involved in proceeding with BMT.

Germline mosaicism for a MECP2 mutation in a man with two Rett daughters.

Rett syndrome is a severe neurodevelopmental disorder that is caused by mutations in the X-linked gene, methyl-CpG binding protein 2 (MECP2). The majority of cases are sporadic, but rarely germline mosaicism can lead to familial cases. Here, we report the first case where germline mosaicism for a MECP2 mutation has been shown in a man. He has two affected daughters who are half sisters, and both have the c.808delC mutation. We show that this mutation is present at a low level in DNA extracted from the patient's semen. This case has implications for genetic counseling, and pre-natal testing should be offered for the partners of men who have a daughter with Rett syndrome.

Gross rearrangements of the MECP2 gene are found in both classical and atypical Rett syndrome patients.

MECP2 mutations are identifiable in approximately 80% of classic Rett syndrome (RTT), but less frequently in atypical RTT. We recruited 110 patients who fulfilled the diagnostic criteria for Rett syndrome and were referred to Cardiff for molecular analysis, but in whom an MECP2 mutation was not identifiable. Dosage analysis of MECP2 was carried out using multiplex ligation dependent probe amplification or quantitative fluorescent PCR. Large deletions were identified in 37.8% (14/37) of classic and 7.5% (4/53) of atypical RTT patients. Most large deletions contained a breakpoint in the deletion prone region of exon 4. The clinical phenotype was ascertained in all 18 of the deleted cases and in four further cases with large deletions identified in Goettingen. Five patients with large deletions had additional congenital anomalies, which was significantly more than in RTT patients with other MECP2 mutations (2/193; p<0.0001). Quantitative analysis should be included in molecular diagnostic strategies in both classic and atypical RTT.

Hereditary coproporphyria: comparison of molecular and biochemical investigations in a large family.

Hereditary coproporphyria (HCP) is the least common of the three autosomal dominant acute porphyrias. To compare the sensitivity of metabolite measurements for the identification of asymptomatic HCP, we carried out a molecular and biochemical investigation of a large family in which HCP is caused by a previously unreported frameshift mutation (c.119delA). Thirteen of 19 asymptomatic family members, aged 10-72 years, were shown by mutational analysis to have HCP. The faecal coproporphyrin isomer III:I ratio was increased in all of these 13 family members; faecal total porphyrin concentration and urinary porphyrin excretion were increased in 11 and 8 of them, respectively. Plasma porphyrin concentrations were marginally increased in three individuals and plasma fluorescence emission scanning showed a porphyrin peak at 618 nm in two of these. Our results add to the evidence that an increased faecal porphyrin coproporphyrin III:I ratio is a highly sensitive test for the detection of clinically latent HCP in individuals over the age of 10 years; its sensitivity below this age remains uncertain. They also show that plasma fluorescence emission scanning is not useful for the investigation of families with HCP.

Hepatoerythropoietic porphyria: a missense mutation in the UROD gene is associated with mild disease and an unusual porphyrin excretion pattern.

Hepatoerythropoietic porphyria (HEP) is an uncommon inherited cutaneous porphyria, related to porphyria cutanea tarda, that results from severe uroporphyrinogen decarboxylase (UROD) deficiency. It is characterized clinically by the onset in early childhood of severe lesions on sun-exposed skin. We describe a man aged 38 years with an unusually mild form of the disease that started in his early teens. Our data confirm that homozygosity for the F46L mutation in the UROD gene causes a mild form of HEP and show that this genotype may be associated with a unique urinary porphyrin excretion pattern in which pentacarboxylic porphyrin predominates.

A mitochondrial DNA sequence variant associated with schizophrenia and oxidative stress.

We have previously reported a changed mitochondrial (mt) gene expression in brain from patients with schizophrenia [Schizophr. Res. 14 (1995) 203]; now, we describe the distribution in the mtDNA from lymphocytes of a heteroplasmic sequence variation that was originally found in the mtDNA from the postmortem brain of a patient with schizophrenia. The variant is m.12027T>C and results in the change from isoleucine to threonine at position 423 of the ND4 subunit of NADH-ubiquinone reductase. Using a PCR-RFLP method, we have determined the heteroplasmy as the ratio of variant to total (variant ratio) at m.12027 in 184 controls and 181 patients with schizophrenia as well as 24 postmortem brain samples. The distribution of variants is bimodal having peaks at variant ratios of 0.262 and 0.732. The variant-rich fraction is very significantly associated with schizophrenia in males (47%), while there is only 18% in control males. There are significantly more variant-rich control females (36%) than control males (18%), suggesting that the female population is less sensitive to the presence of a variant in terms of liability to schizophrenia. In variant-rich samples from postmortem brain originating from both sexes, there is an increased superoxide production, suggesting that the variation contributes to oxidative stress. Antioxidant glycosides, such as quercetin rutoside, quench the superoxide production without (in contrast to neuroleptic drugs) interfering with the electron transfer activity of the reductase.

Sporadic case of fatal encephalopathy with neonatal onset associated with a T158M missense mutation in MECP2.

The case of a male infant with neonatal encephalopathy and a de novo MECP2 mutation is reported. The presenting phenotype of decelerating head growth, spasticity, scoliosis, and central respiratory disturbance raised suspicions of the diagnosis. Neonatal encephalopathy in males is part of a spectrum of disorders caused by MECP2 dysfunction.