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C Camaschella

Publications and source records attributed to C Camaschella.

At least 37 records · Page 2Linked to original sources
PubMed1999

Juvenile hemochromatosis locus maps to chromosome 1q.

Juvenile hemochromatosis (JH) is an autosomal recessive disorder that leads to severe iron loading in the 2d to 3d decade of life. Affected members in families with JH do not show linkage to chromosome 6p and do not have mutations in the HFE gene that lead to the common hereditary hemochromatosis. In this study we performed a genomewide search to map the JH locus in nine families: six consanguineous and three with multiple affected patients. This strategy allowed us to identify the JH locus on the long arm of chromosome 1. A maximum LOD score of 5.75 at a recombination fraction of 0 was detected with marker D1S498, and a LOD score of 5. 16 at a recombination fraction of 0 was detected for marker D1S2344. Homozygosity mapping in consanguineous families defined the limits of the candidate region in an approximately 4-cM interval between markers D1S442 and D1S2347. Analysis of genes mapped in this interval excluded obvious candidates. The JH locus does not correspond to the chromosomal localization of any known gene involved in iron metabolism. These findings provide a means to recognize, at an early age, patients in affected families. They also provide a starting point for the identification of the affected gene by positional cloning.

Adolescent↗
PubMed1999

Recurrent mutations in the iron regulatory element of L-ferritin in hereditary hyperferritinemia-cataract syndrome.

BACKGROUND AND OBJECTIVE: Hereditary hyperferritinemia-cataract syndrome (HHCS) is an autosomal dominant disorder characterized by bilateral cataracts and increased serum and tissue L-ferritin, in the absence of iron overload. The deregulation of ferritin production is caused by heterogeneous mutations in the iron regulatory element (IRE) of L-ferritin that interfere with the binding of iron regulatory proteins. DESIGN AND METHODS: We have identified several patients from three unrelated Italian families with HHCS. Iron parameters were assessed by standard methods. The IRE element of L-ferritin was amplified by PCR using appropriate primers and directly sequenced. RESULTS: Ferritin levels ranged from 918 microg/L to 2490 microg/L in the patients studied. In one family bilateral cataracts were diagnosed early in life, whereas in the others cataracts were diagnosed around 40-50 years. The female proband of family 3 presented with a severe iron deficiency anemia, which was unrecognized because of the increased ferritin values. Sequencing of the IRE element of L-ferritin in the probands of the three families identified three different nucleotide substitutions (+32 GAE A, +40 AAE G and +39 CT) in the IRE of L-ferritin. These mutations have already been reported in unrelated subjects of different ethnic origins. INTERPRETATION AND CONCLUSIONS: Our findings are consistent with recurrent mutations associated with HHCS and underline the importance of this syndrome in the differential diagnosis of unexplained hyperferritinemia. In addition, the findings highlight the role played by transferrin saturation in the diagnosis of iron deficiency in these patients.

Adult↗
PubMed1999

The influence of hemochromatosis mutations on iron overload of thalassemia major.

BACKGROUND AND OBJECTIVE: Hemochromatosis is a genetic form of iron overload due to a defective HFE gene. Secondary iron overload is the main complication in transfusion-dependent thalassemia patients. In this work we have examined the prevalence of HFE mutations in thalassemia major and evaluated the degree of iron overload of patients with and without HFE mutations. DESIGN AND METHODS: HFE mutations were studied in 71 Italian thalassemic patients and in 189 normal controls, using PCR and restriction enzyme analysis. The degree of iron overload, assessed by serum ferritin and liver iron concentration (LIC), was compared in 17 patients with mutations in the HFE gene, and in 17 subjects with wild type HFE genotype. The two groups of patients had comparable globin gene mutations, were matched for age and were homogeneous for transfusion and chelation history. In all cases the iron balance calculated on the basis of transfusion regimen and iron excreted by chelation was available. RESULTS: The allele frequencies of C282Y and H63D were respectively 1.4% and 12.7% in patients and 1.1% and 11.4% in controls. No case of C282Y homozygosity was recorded among patients. No significant difference was found in terms of serum ferritin, LIC, or the age at chelation start between patients with and without HFE mutations. The single patient with H63D homozygosity was severely iron-loaded. INTERPRETATION AND CONCLUSIONS: Our data suggest that the presence of a single mutation in the HFE gene does not influence the severity of iron loading in thalassemia patients following a regular transfusion and chelation program.

Adolescent↗
PubMed1998

Heterogeneity of hemochromatosis in Italy.

BACKGROUND & AIMS: Patients with hemochromatosis show variable phenotype expression. We evaluated the frequency of hemochromatosis gene (HFE) mutations and the contribution of HFE genotype, ancestral haplotype, ethnic background, and additional factors (alcohol intake, hepatitis viruses, and beta-thalassemia trait) to the severity of iron overload in a large series of Italian patients with a hemochromatosis phenotype. METHODS: HFE genotype was studied in 188 patients. Phenotype evaluation was available in 153 men and 20 women and was based mainly on iron removed. HFE genotype was determined by a polymerase chain reaction restriction assay and ancestral haplotype through D6S265 and D6S105 microsatellite analysis. RESULTS: The frequency of C282Y homozygotes was 64%, with a decreasing gradient from north to south. C282Y homozygotes showed more severe iron overload than the other HFE genotypes. In the same group, ancestral haplotype was associated with a more severe phenotype. Additional factors may favor the development of a relatively mild hemochromatosis phenotype in patients nonhomozygous for the C282Y mutation. CONCLUSIONS: Hemochromatosis in Italy is a nonhomogenous disorder in which genetic and acquired factors are involved. In patients with a single or no HFE mutation, further studies will enable a differentiation between true genetic disorders and interactions between genetic and acquired factors.

Adult↗
PubMed1998

Juvenile haemochromatosis.

Juvenile haemochromatosis (JH) is an autosomal recessive disorder which leads to early-onset, severe iron overload. The disease affects both sexes equally. Iron parameters and tissue iron distribution are similar to those in middle-life haemochromatosis (which is linked to the HFE gene). Endocrine manifestations, especially hypogonadism, and heart failure are the most prominent clinical features. Liver involvement, although present, is clinically less relevant. Genetic evidence indicates that JH is a disorder distinct from HFE-linked disease. Patients do not have mutations in the HFE gene, and the study of selected families has excluded a linkage to the interval of chromosome 6p where the HFE gene resides. The distinction between the two disorders raises the possibility that the different clinical presentation of JH is not only age-related but probably depends on a different biochemical defect. Early diagnosis of JH is important to avoid cardiac complications which can lead to premature death. As with HFE-linked disease, JH is responsive to phlebotomies.

Adolescent↗
PubMed1998

Molecular genetics and control of iron metabolism in hemochromatosis.

BACKGROUND AND OBJECTIVES: Hereditary hemochromatosis (HC) is an inborn error of iron metabolism that leads to progressive iron overload. Considerable advances in the knowledge of molecular events in iron metabolism have been recently obtained. These molecular findings, the cloning of the gene responsible for HC (HFE gene) and the results of preliminary studies on the HFE protein prompted us to review this topic. INFORMATION SOURCES: The material examined in this review article includes papers and abstracts published in the Journals covered by the Science Citation Index and Medline. The authors have been working in the field of HC for several years and have contributed eleven of the quoted papers. STATE OF ART AND PERSPECTIVE: HC is now recognized as the genetic disease characterized by the homozygosity for the Cys-->Tyr substitution at position 282 (C282Y) of the HFE protein. The mutation abolishes the association of the HFE protein with beta 2-microglobulin (beta 2M), making the complex unable to gain the cell surface. Thus HC is an example of abnormal trafficking of the corresponding proteins. It is clear by the analysis of its structure that HFE protein is not an iron transporter itself, but has a regulatory role in iron metabolism. Its peculiar localization in the crypt cells of the small intestine suggests an important role in iron trafficking at this level. However, other proteins are involved in iron uptake, as the recently cloned Nramp2, the first iron transporter discovered in mammalians. Nramp2 has a recognized role both in the intestinal iron uptake and in the iron transport within the erythroblast. The relationships between HFE and Nramp2 are still unexplored. The recent association of HFE gene with transferrin receptor (TfR) in trophoblast cells opens new possibilities on its role in cellular iron uptake. The existence of other forms of genetic iron overload suggests that the scenario of iron proteins is not yet fully defined. Further studies in this field will contribute to our knowledge of iron metabolism regulation in humans.

Hemochromatosis↗
PubMed1997

Different hematological phenotypes caused by the interaction of triplicated alpha-globin genes and heterozygous beta-thalassemia.

The pathophysiology and clinical severity of beta-thalassemia are related to the degree of alpha/non-alpha-chain imbalance. A triplicated alpha-globin gene locus can exacerbate effects of excess alpha-chains caused by a defective beta-globin gene, although this is not observed in all cases. Extensive studies on this condition are lacking. We report a group of 17 patients who are heterozygous for both the alpha alpha alpha(anti-3.7) allele and a mutation in the beta-globin gene cluster. Their clinical phenotypes varied: six had mild anemia with microcytosis and hypochromia, while 11 had more severe anemia with splenomegaly requiring splenectomy (three cases) and blood transfusions (four cases). Different phenotypes were also evident in the presence of the same beta-thalassemia mutation: in one family, two individuals had the same alpha- and beta-globin genotypes but presented with different hematologic phenotypes. In addition, the complex interaction involving a triplicated alpha-globin gene, beta39- and delta+27-thalassemia mutations is studied in a family with two siblings presenting with hemolytic anemia, normal Hb A2 and increased Hb F. Analysis of this series of patients suggests that additional genetic determinants play a role in modulating phenotypic expression in individuals with identical alpha- and beta-globin genotypes. Interaction with a triplicated alpha-gene can play a role in the clinical presentation of patients with defective beta-globin gene expression and should be considered in the diagnosis of atypical cases.

Adult↗
PubMed1997

Mutation analysis of the HLA-H gene in Italian hemochromatosis patients.

Hemochromatosis (HH) is an inborn error of iron metabolism, frequent among Caucasians, characterized by progressive iron loading that, if untreated, causes high morbidity and death. HLA-H, a putative HH gene, has recently been isolated. The large majority of patients so far studied are homozygous for a single mutation, which results in a cysteine-to-tyrosine substitution at amino acid 282 of the protein. A second, less frequent, variant, His63Asp, has an undefined role in the pathogenesis of the disease. Here we report that the Cys282Tyr change accounts for 69% of HH chromosomes in a series of 75 unrelated Italian patients who fulfilled well-defined criteria for HH diagnosis. Sixty-four percent of patients were Cys282Tyr homozygous, 10% were heterozygous, and 21% carried the normal allele. The same mutation was rare in normal controls. The His63Asp variant was less frequent but had a similar frequency among affected and normal chromosomes. Subjects without two copies of the Cys282Tyr change were both isolated patients and individuals from families with a 6p-linked disease. Mutation analysis of the HLA-H gene, carried out by RNA-SSCP in the latter patients, did not reveal any significant nucleotide abnormality in coding sequences and intron-exon boundaries. The absence of mutations in HLA-H gene was confirmed in three cases by direct sequencing. Major deletions or rearrangements of the gene were excluded by Southern blotting. The existence of patients with clinical and histological features of HH, but without mutations in HLA-H gene, suggests that in Italy the disease is more heterogeneous than reported in northern Europe.

Chromosomes, Human, Pair 6↗
PubMed1997

A recombination event close to HFE gene in hereditary hemochromatosis.

A candidate gene for Hereditary Hemochromatosis (HFE) has been recently cloned from a region 4 cM telomeric to HLA-A on the short arm of chromosome 6. This gene, defined HFE, is mutated in a high proportion of HFE patients. Positional cloning of HFE has been difficult, because of the extended region of linkage disequilibrium observed around the gene and of the rarity of recombination events in this DNA area. Here we describe a crossover in an Italian HFE patient which occurred close to the HFE gene in a restricted interval between D6S2221 and D6S2240-D6S2238 markers. The molecular analysis of this event and the segregation of the HFE mutations in the family are consistent with the position of the HFE gene telomeric to D6S2221.

Adult↗
PubMed1996

Construction of a YAC contig covering human chromosome 6p22.

A contig covering human chromosome 6p22 that consists of 134 YAC clones aligned based on the presence/absence of 52 DNA markers is presented. This contig overlaps with the 6p23 contig at its telomeric end and with the 6p21.3 contig at its centromeric end. The order of loci within the contig resolves the relative positions of several genetically mapped markers. Among the additional markers used here, there are eight novel PCR assays. The 12 known genes and anonymous ESTs located within the contig establish a first step toward a transcriptional map of this region. The instability of YAC clones observed during this work is also discussed.

Chromosome Mapping↗
PubMed1996

Hereditary hemochromatosis: generation of a transcription map within a refined and extended map of the HLA class I region.

Hereditary hemochromatosis, a common severe inherited disease, maps to the short arm of chromosome 6 close to the HLA-A locus. Recently, linkage data on Italian and French populations confirmed this location, while a similar analysis on Australian and British populations located the gene closer to D6S105, a marker residing telomeric of HLA-A. To increase our knowledge on the region of highest linkage disequilibrium in our population and possibly to identify the disease gene, a 1.2-Mb detailed physical and transcription map was generated, spanning the HLA class I region. Thirty-eight unique cDNA fragments, retrieved following the hybridization of immobilized YACs to primary pools of cDNAs prepared from RNA of fetal brain, adult brain, liver, placenta, and the CaCo2 cell line, were characterized. All cDNA fragments were positioned in a refined and extended map of the human major histocompatibility complex spanning from HLA-E to approximately 500 kb telomeric of HLA-F. The localization of known genes was refined, and a new gene from the RNA helicase superfamily was identified. Overall, 14 transcription units in addition to the HLA genes have been detected and integrated in the map. Thirteen cDNA fragments show no similarity with known sequences and could be candidates for the disease. Their characterization and assessment for involvement in hemochromatosis are still under investigation. Seven new polymorphisms, some tightly linked to the disease, were also identified and localized.

Animals↗