Molecular Analysis of 55 Spanish Patients with Acute Intermittent Porphyria

Acute intermittent porphyria (AIP) results from a decreased activity of hepatic hydroxymethylbilane synthase (HMBS), the third enzyme in the heme biosynthetic pathway. AIP is an autosomal dominant disorder with incomplete penetrance, characterized by acute neurovisceral attacks precipitated by several factors that induce the hepatic 5-aminolevulinic acid synthase, the first enzyme in the heme biosynthesis. Thus, a deficiency in HMBS activity results in an overproduction of porphyrin precursors and the clinical manifestation of the disease. Early diagnosis and counselling are essential to prevent attacks, and mutation analysis is the most accurate method to identify asymptomatic carriers in AIP families. In the present study, we have investigated the molecular defects in 55 unrelated Spanish patients with AIP, identifying 32 HMBS gene mutations, of which six were novel and ten were found in more than one patient. The novel mutations included a missense, an insertion, two deletions, and two splice site variants. Prokaryotic expression studies demonstrated the detrimental effect for the missense mutation, whereas reverse transcription-PCR and sequencing showed aberrant splicing caused by each splice site mutation. These results will allow for an accurate diagnosis of carriers of the disease in these families. Furthermore, they increase the knowledge about the molecular heterogeneity of AIP in Spain.

Mutation in CNR1 Gene and VEGF Expression in Esophageal Cancer

Aims and background

Cannabinoid receptors have an impact on gastrointestinal function, but it remains unknown whether mutations may affect tumor susceptibility in patients with esophageal carcinoma. The aim of this study was to determine mutation in the cannabinoid receptor-1 (CNR1) gene and its relation to vascular endothelial growth factor (VEGF) expression as an angiogenic and poor prognostic factor.

Methods

179 esophageal tissue samples from 69 patients (29 with esophageal cancer and 40 controls) were studied. CNR1 gene mutation (1359 G → A in codon 453) was detected with PCR, using the MspI restriction enzyme. VEGF was determined by immunoassay.

Results

Genotyping in control patients’ samples revealed that 24/40 were G/G wild type and 16/40 were G/A; no samples were A/A. Of the 139 tissue samples from the 29 esophageal cancer patients, 15 were G/G homozygous, 85 G/A heterozygous, 11 had an A/A genotype and 28 were without amplification. In the normal tissue adjacent to tumor, some mutations were observed. The overall survival time was reduced in patients with the A/A type in all their 5 samples, in comparison to G/G type (P = 0.04, chi-square: 4.26). VEGF expression was higher in tumor than nontumor areas (P <0.025). VEGF expression was not correlated with survival time.

Conclusions

Our preliminary findings in esophageal tissue showed a high frequency of G → A mutation in the CNR1 gene. No correlation between VEGF expression and gene receptor mutation was found. Patients with mutation in all their samples had a reduced survival time.

A novel mutation in the SLC40A1 gene associated with reduced iron export in vitro

Ferroportin disease is an inherited disorder of iron metabolism and is caused by mutations in the ferroportin gene (SLC40A1). We present a patient with hyperferritinemia, iron overload in the liver with reticuloendothelial distribution and also in the spleen, and under treatment with erythropheresis. A molecular study of the genes involved in iron metabolism (HFE, HJV, HAMP, TFR2, SLC40A1) was undertaken. In vitro functional studies of the novel mutation found in the SLC40A1 gene was performed. The patient was heterozygous for a novel mutation, c.386T>C (p.L129P) in the SLC40A1 gene; some of his relatives were also heterozygous for this mutation. In vitro functional studies of the L129P mutation on ferroportin showed it impairs its capacity to export iron from cells but does not alter its sensitivity to hepcidin. These findings and the iron overload phenotype of the patient suggest that the novel mutation c.386T>C (p.L129P) in the SLC40A1 gene has incomplete penetrance and causes the classical form of ferroportin disease.

Two novel mutations in the SLC40A1 and HFE genes implicated in iron overload in a Spanish man

The most common form of hemochromatosis is caused by mutations in the HFE gene. Rare forms of the disease are caused by mutations in other genes. We present a patient with hyperferritinemia and iron overload, and facial flushing. Magnetic resonance imaging was performed to measure hepatic iron overload, and a molecular study of the genes involved in iron metabolism was undertaken. The iron overload was similar to that observed in HFE hemochromatosis, and the patient was double heterozygous for two novel mutations, c.-20G>A and c.718A>G (p.K240E), in the HFE and ferroportin (FPN1 or SLC40A1) genes, respectively. Hyperferritinemia and facial flushing improved after phlebotomy. Two of the patient's children were also studied, and the daughter was heterozygous for the mutation in the SLC40A1 gene, although she did not have hyperferritinemia. The patient presented a mild iron overload phenotype probably because of the two novel mutations in the HFE and SLC40A1 genes.

Hepcidin treatment in Hfe-/- mice diminishes plasma iron without affecting erythropoiesis

BACKGROUND

Iron is essential for mammalian metabolism and its cellular concentration is controlled by regulating its acquisition and storage. Haemochromatosis is a condition involving iron overload that is characterised by increased duodenal iron absorption and a progressive accumulation of iron in vital organs. Hepcidin is the main hormone that regulates iron homoestasis and it is secreted by the liver.

MATERIALS AND METHODS

We have studied how extended hepcidin administration affects the iron load status, plasma and tissue iron concentration, erythropoiesis and the expression of proteins involved on iron homeostasis in haemochromatotic (Hfe(-/-)) and wild-type mice.

RESULTS

Hepcidin reverted the high plasma iron concentrations in Hfe(-/-) mice to normal values. The high concentration of hepatic iron was not altered in the liver of these Hfe(-/-) mice. Hepcidin administration did not disturb erythropoiesis in either Hfe(-/-) or wild-type mice and likewise, hepcidin did not modify the expression of any protein analysed in the liver, duodenum or spleen of Hfe(-/-) and wild-type mice. These data confirm that hepcidin administration diminishes plasma iron concentrations.

CONCLUSION

Treatment with sustained doses of hepcidin diminishes plasma iron concentrations in Hfe(-/-) mice.

Bone marrow transplantation into hemochromatotic mice decreases hepatic and duodenal iron overload

Human hereditary hemochromatosis is a disorder of iron homeostasis characterized by increased absorption of iron and its deposition in parenchymal organs. The maintenance of iron homeostasis is regulated by molecules involved in the absorption, transport, storage and redox of iron. The potential of hematopoietic stem cell therapy for liver diseases has been studied in some experimental animal models. Our objective was to evaluate the effect of bone marrow transplantation from wild type mice on the status of iron overload in Hfe knockout hemochromatotic mice (Hfe(-/-)). The transplanted cells were detected in the liver (11% of the total cells) and characterized as hepatocytes and myofibroblasts. They were also detected in the duodenum and characterized as myofibroblasts. The iron content in the Hfe(-/-) mice descended 2.9-fold in the liver and 2.4-fold in the duodenum 6 months after transplantation. Non-significant changes of relative mRNA abundance of genes of iron metabolism were observed in the liver and duodenum of Hfe(-/-) transplanted mice. At 6 months after transplantation the proportion of Hfe mRNA in Hfe(-/-) mice reached 3.8% of the levels in wild type mice in the liver and 1.6% in the duodenum. In conclusion, adult stem cells from bone marrow transplant were able to differentiate into hepatocytes and myofibroblasts in hemochromatotic mice. Bone marrow transplantation assisted in reducing the iron overload in this murine model of hemochromatosis. These findings might contribute to the knowledge of pathways involved in the regulatory system of iron homeostasis.

Cerebrospinal fluid levels of non-neurotransmitter amino acids in patients with Alzheimer's disease

We measured the CSF levels of 21 and the plasma levels of 24 amino acids in 37 patients with Alzheimer's disease (AD) and in 32 matched controls. We used an ion-exchange chromatography method. When compared with controls, AD patients had lower CSF levels of phosphoserine, citrulline, alfa-aminobutyric acid, methionine, and ethanolamine; and higher CSF levels of threonine, serine, lysine, histidine and arginine. However, when expressed relative to CSF protein, CSF levels of serine, lysine, histidine, and arginine, were normal. AD patients had higher plasma levels of phosphoserine, threonine, citrulline, hydroxyproline, and proline; and lower plasma levels of alfa-aminobutyric acid, methionine, leucine and ethanolamine. The CSF/plasma ratios of phosphoserine, serine, citrulline, alfa-aminobutyric acid and arginine were significantly lower in AD patients than those of controls. CSF amino acid levels were not related with the duration and severity of the disease.

Cerebrospinal fluid levels of alpha-tocopherol (vitamin E) in Parkinson's disease

We compared CSF and serum levels, and the CSF/serum ratio of alpha-tocopherol (vitamin E), measured by HPLC, in 34 patients with Parkinson's disease (PD) and 47 controls. CSF and serum vitamin E levels were correlate. The mean CSF and serum vitamin E levels, and the CSF/serum ratio of PD patients did not differ significantly between the groups. There was no influence of antiparkinsonian therapy on CSF vitamin E levels. CSF vitamin E levels did not correlate with age, age at onset, duration of the disease, scores of the Unified Parkinson Disease Rating Scale of the Hoehn and Yahr staging in the PD group. These results suggest that CSF vitamin E concentrations are unrelated with the risk for PD.

Cerebrospinal fluid levels of alpha-tocopherol (vitamin E) in Alzheimer's disease

We compared CSF and serum levels, and the CST/serum ratio of alpha-tocopherol (vitamin E), measured by HPLC, in 44 apparently well-nourished patients with Alzheimer's disease (AD) and 37 matched controls. CSF and serum vitamin E levels were correlated, both in AD patients and in controls. The mean CSF and serum vitamin E levels were significantly lower in AD patients, and the CSF/serum ratio of AD patients did not differ significantly between the 2 study groups. CSF vitamin E levels did not correlate with age, age at onset, duration of the disease and score of the Minimental State Examination in the AD group. Weight and body mass index were significantly lower in AD patients than in controls. These results suggest that low CSF and serum vitamin E concentrations in AD patients could be related with a deficiency of dietary intake of vitamin E.