Extremely rare association of HFE mutations with porphyria cutanea tarda in Japanese patients

Porphyria cutanea tarda: Recent update

Porphyria cutanea tarda (PCT) is the most common human porphyria, due to hepatic deficiency of uroporphyrinogen decarboxylase (UROD), which is acquired in the presence of iron overload and various susceptibility factors, such as alcohol abuse, smoking, hepatitis C virus (HCV) infection, HIV infection, iron overload with HFE gene mutations, use of estrogens, and UROD mutation. Patients with familial or type II PCT due to autosomal dominant UROD mutation also require other susceptibility factors, as the disease phenotype requires hepatic UROD deficiency to below 20% of normal. PCT clinically manifests with increased skin fragility and blistering skin lesions on sun exposed areas. The common age of presentation is 5th to 6th decade and occurs slightly more commonly in males. Although mild liver biochemical profile are common, advanced fibrosis and cirrhosis with hepatocellular carcinoma (HCC) can occasionally develop. Screening for HCC using ultrasound examination is recommended in PCT patients, especially with cirrhosis and advanced fibrosis. PCT is effectively and readily treatable with the use of either repeated phlebotomy or use of 100 mg hydroxychloroquine orally twice a week, and both the treatments are equally effective and safe. With the advent of new or direct antiviral agents for HCV infection, treatment of concomitant HCV has become safer and effective. Data are emerging on the benefit of these drugs as monotherapy for both PCT and HCV. After the achievement of remission of PCT, there remains a potential for relapse, especially when the susceptibility factors are not adequately controlled. Scanty data from retrospective and observational studies shows the relapse rate to be somewhat higher after remission with low-dose hydroxychloroquine as compared to phlebotomy induced remission. Future studies are needed on exploring mechanism of action of 4-aminoquinolines, understanding interaction of HCV and PCT, and relapse of PCT on long-term follow-up.

Therapy of porphyria cutanea tarda

Porphyria cutanea tarda (PCT) is the most common type of porphyria. There is an association of PCT with haemochromatosis, diabetes mellitus and hepatitis C infection. The basis of treatment of PCT consists of three elements: avoidance of triggering factors, iron depletion and porphyrin elimination. Alcohol and certain systemic medical drugs, such as oestrogens (or tuberculostatics), should be considered as triggering factors, and as far as possible, avoided. Other triggering factors, such as chronic haemodialysis in renal insufficiency, need a different approach. The hallmark in iron depletion is phlebotomy. Porphyrin elimination is achieved using low-dose chloroquin therapy. The treatment is safe and effective but has its limits in cases with haemochromatosis (HFE) gene mutations. Here iron depletion needs additional phlebotomy. In patients with chronic haemodialysis-associated PCT, chloroquine is ineffective. Erythropoietin, desferroxamine and small-volume phlebotomy have been employed to control the disease. Childhood PCT is very rare. No controlled studies are available, but published experience suggests that body weight-adapted chloroquine therapy or small volume phlebotomy might be useful.

Porphyria Cutanea Tarda in a Swedish Population: Risk Factors and Complications

There are varying reports on the prevalence of risk factors in porphyria cutanea tarda (PCT). We reviewed 84 patients with PCT in a restricted uptake area in Gothenburg, Sweden and evaluated different potential risk factors for the disease and complications. Besides a thorough medical history, the patients were investigated with urinary porphyrin analyses, transferrin saturation, ferritin and liver tests. Subsamples of patients were tested for antibodies to hepatitis C virus (n = 68), haemochromatosis gene mutations (n = 58) and with the oral glucose tolerance test (n = 31). We found a prevalence of about 1 patient with PCT in 10 000 inhabitants. Nineteen (23%) patients reported heredity for PCT. Identified risk factors were alcohol abuse (38% of male patients), oestrogen treatment (55% of female patients), anti-hepatitis C virus positivity (29% of male patients), diabetes (17%) or impaired glucose tolerance (45% of tested patients) and haemochromatosis gene mutations (57% of tested patients). All patients positive for anti-hepatitis C virus belonged to the non-hereditary group. During follow-up we observed a high incidence of stroke, no case of hepatocellular carcinoma and a normal life expectancy.

Porphyrias in Japan: Compilation of All Cases Reported through 2002

The first case of porphyria on record in Japan was a patient with congenital erythropoietic porphyria (CEP) reported by Sato and Takahashi in 1920. Since then until the end of December 2002, 827 cases of porphyrias have been diagnosed from characteristic clinical and/or laboratory findings (463 males, 358 females, and 6 of unknown sex). Essentially all inherited porphyrias have been found in Japan, with the incidences and clinical symptoms generally being similar to those reported for other countries. The male-female ratio was approximately 1:1 for CEP, whereas it was higher for erythropoietic protoporphyria. In contrast, preponderances of female patients exist with acute hepatic porphyrias, such as acute intermittent porphyria (AIP), variegate porphyria (VP), and hereditary coproporphyria (HCP), and with undefined acute porphyria. Although porphyria cutanea tarda (PCT) is believed to be increasing recently in women in other countries because of smoking and the use of contraceptives, it is still by far more prominent in males in Japan than in females. The recent increasing contribution of hepatitis C virus infection to PCT in Japan has also been recognized. but there have been no PCT cases in Japan with HFE gene mutations. Familial occurrence and consanguinity were high for CEP, as expected; however, significant consanguinity was also noted in families where CEP, AIP, HCP, VP, or PCT occurred as a single isolated case without a family history of disease. This survey also revealed that as many as 71% of acute hepatic porphyria cases were initially diagnosed as nonporphyria and later revised or corrected to porphyria, indicating the difficulty of diagnosing porphyria in the absence of specific laboratory testing for porphyrins and their precursors in urine, stool, plasma, and erythrocyte samples.

Hemochromatosis (HFE) gene mutations and hepatitis C virus infection as risk factors for porphyria cutanea tarda in Hungarian patients

AIM

It is not clear whether the mutations in hemochromatosis (HFE) gene and hepatitis C virus (HCV) infection act independently in the pathogenesis of porphyria cutanea tarda (PCT). The prevalence of both risk factors varies greatly in different parts of the world. PCT patients from Hungary were evaluated to assess both factors.

METHODS

The prevalence of C282Y and H63D mutations in the HFE gene was determined in 50 PCT patients and compared with the reported control frequencies. Furthermore, the presence of HCV infection was determined and related to the patients' HFE gene status.

RESULTS

The C282Y mutation was found in 8/50 cases (three homozygotes and five heterozygotes), with an 11% allele frequency (vs. 3.8% control) (P<0.05). Seventeen patients were heterozygous, one was homozygous for the H63D mutation, allele frequency 19%, which did not differ significantly from the reported control prevalence of 12.3%. Twenty-two patients (44%) were HCV-RNA positive; six out of them were heterozygous for H63D mutation, one only for the C282Y mutation and one was compound heterozygous for both mutations.

CONCLUSION

HCV infection and HFE C282Y mutation may probably be independent predisposing factors for development of PCT in Hungarian patients.

HFE mutations and transferrin receptor polymorphism analysis in porphyria cutanea tarda: a prospective study of 36 cases from southern France

BACKGROUND

Porphyria cutanea tarda (PCT) is associated in most cases with iron overload, which may participate in decreased activity of uroporphyrinogen decarboxylase in the liver. The aetiology of this iron overload remains unknown; however, it has been demonstrated that mutations of HFE, the genetic haemochromatosis gene, might be present in a significant proportion of Anglo-Saxon and Italian patients. Furthermore, transferrin receptor polymorphism may influence the affinity of this receptor to its ligand with a subsequent increase of cellular iron absorption and storage.

OBJECTIVES

To evaluate the incidence and spectrum of HFE mutations and the relative frequency of the two main alleles of transferrin receptor in patients with PCT originating from southern France, and to evaluate the relationship of these genetic data with iron status, and with hepatitis B and C and human immunodeficiency virus (HIV) infections.

METHODS

Thirty-six consecutive patients with either sporadic or familial PCT were prospectively included between 1997 and 2000. Search for the presence of the three main mutations of the HFE gene and identification of the transferrin receptor alleles were performed using polymerase chain reaction followed by enzymatic digestion. Iron parameters and viral status for hepatitis B and C viruses and HIV were determined.

RESULTS

Seven patients (19%) showed heterozygous C282Y mutation, but no C282Y homozygote was present; five patients (14%) carried homozygous H63D mutation, while eight (22%) were heterozygous for this mutation. One patient was heterozygous for the S65C mutation (3%). Iron parameters demonstrated overload in all patients, without a clear difference between patients with and without deleterious mutations of the HFE gene. Infection by hepatitis C virus was documented in 20 patients (56%), and was significantly less frequent in patients with deleterious HFE mutations. The profile of transferrin receptor alleles in PCT patients did not show significant variation compared with the general population.

CONCLUSIONS

This study confirms the high frequency of HFE mutations in patients with PCT and supports the hypothesis that HFE gene abnormalities might play a significant part in the PCT pathomechanism, probably through iron overload; by contrast, transferrin receptor polymorphisms do not appear to play a significant part in iron overload in PCT.

Co-inheritance of mutations in the uroporphyrinogen decarboxylase and hemochromatosis genes accelerates the onset of porphyria cutanea tarda

Porphyria cutanea tarda is a skin disease caused by photosensitization by porphyrins whose accumulation is caused by deficiency of hepatic uroporphyrin- ogen decarboxylase activity. Mutations in the uroporphyrinogen decarboxylase gene are present in the low-penetrant, autosomal dominant familial form but not in the commoner sporadic form of porphyria cutanea tarda. We have investigated the relationship between age of onset of skin lesions and mutations (C282Y, H63D) in the hemochromatosis gene in familial (19 patients) and sporadic porphyria cutanea tarda (65 patients). Familial porphyria cutanea tarda was identified by mutational analysis of the uroporphyrinogen decarboxylase gene. Five previously described and eight novel mutations (A80S, R144P, L216Q, E218K, L282R, G303S, 402-403delGT, IVS2 + 2 delTAA) were identified. Homozygosity for the C282Y hemochromatosis mutation was associated with an earlier onset of skin lesions in both familial and sporadic porphyria cutanea tarda, the effect being more marked in familial porphyria cutanea tarda where anticipation was demonstrated in family studies. Analysis of the frequencies of hemochromatosis genotypes in each type of porphyria cutanea tarda indicated that C282Y homozygosity is an important susceptibility factor in both types but suggested that heterozygosity for this mutation has much less effect on the development of the disease.