Clara Camaschella

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.

Natural history of juvenile haemochromatosis

Summary. Juvenile haemochromatosis or haemochromatosis type 2 is a rare autosomal recessive disorder which causes iron overload at a young age, affects both sexes equally and is characterized by a prevalence of hypogonadism and cardiopathy. Patients with haemochromatosis type 2 have been reported in different ethnic groups. Linkage to chromosome 1q has been established recently, but the gene remains unknown. We report the analysis of the phenotype of 29 patients from 20 families of different ethnic origin with a juvenile 1q‐associated disease. We also compared the clinical expression of 26 juvenile haemochromatosis patients with that of 93 C282Y homozygous males and of 11 subjects with haemochromatosis type 3. Patients with haemochromatosis type 2 were statistically younger at presentation and had a more severe iron burden than C282Y homozygotes and haemochromatosis type 3 patients. They were more frequently affected by cardiopathy, hypogonadism and reduced glucose tolerance. In contrast cirrhosis was not statistically different among the three groups. These data suggest that the rapid iron accumulation in haemochromatosis type 2 causes preferential tissue damage. Our results clarify the natural history of the disease and are compatible with the hypothesis that the HFE2 gene has greater influence on iron absorption than other haemochromatosis‐associated genes.

Significance of a new type of human fetal hemoglobin carrying a replacement isoleucine → threonine at position 75 (E 19) of the γ chain

SummaryA new type of hemoglobin F, in which isoleucine in position 75 (E 19) of the γ chain is replaced by a threonine residue, has been found in 29 out of 32 homozygotes for β thalassemia. The amount of this hemoglobin ranges from traces to 40% of the total Hb F. The same γ75 Thr chain is also present in the Hb F of 40% of normal newborns and premature infants examined, of one 14-week-old fetus and in one out of 3 patients with aplastic anemia and raised levels of Hb F. Our results strongly suggest that the synthesis of this new chain is under the control of a γ gene nonallelic with those coding for Aγ and Gγ chains.

Haemochromatosis in patients with beta-thalassaemia trait.

Severe iron overload has been reported in patients with the β‐thalassaemia trait. Studies performed before the discovery of the haemochromatosis gene (HFE) have yielded conflicting results: some suggest that iron overload might arise from the interaction of the β‐thalassaemia trait with heterozygosity for haemochromatosis, some with homozygosity for haemochromatosis and others that it was unrelated to haemochromatosis. We have studied the clinical phenotype, iron indices and HFE genotypes of 22 unrelated patients with the β‐thalassaemia trait and haemochromatosis, the inheritance of chromosome 6p and 1q haplotypes in families of non‐homozygous C282Y probands and serum measures of iron status in relatives heterozygous for C282Y with or without the β‐thalassaemia trait. We demonstrate that the β‐thalassaemia trait aggravates the clinical picture of C282Y homozygotes, favouring higher rates of iron accumulation and the development of severe iron‐related complications. We suggest that the coexistence of the β‐thalassaemia trait might also increase the risk of iron overload in patients with HFE genotypes at a mild risk of haemochromatosis. Our findings do not support the hypothesis that the association of the β‐thalassaemia trait with a single C282Y or H63D allele might lead to iron overload and suggest that other non‐HFE‐related inherited factors are present in haemochromatosis patients with incomplete HFE genotypes.

Clinical, biochemical and molecular findings in a series of families with hereditary hyperferritinaemia-cataract syndrome.

Hereditary hyperferritinaemia–cataract syndrome (HHCS) is an autosomal dominant disease caused by mutations in the iron responsive element (IRE) of the l‐ferritin gene. Despite the elucidation of the genetic basis, the overall clinical spectrum of HHCS has been less well studied as, to date, only individual case reports have been described. Therefore, we studied a total of 62 patients in 14 unrelated families, with nine different mutations. No relevant symptoms other than visual impairment were found to be associated with the syndrome. A marked phenotypic variability was observed, particularly with regard to ocular involvement (i.e. age range at which cataract was diagnosed in 16 subjects with the C39T: 6–40u2003years). Similarly, serum ferritin levels varied substantially also within subjects sharing the same mutation (i.e. range for the A40G: 700–2412u2003µg/l). We followed an HHCS newborn in whom well‐defined lens opacities were not detectable either at birth or at 1u2003year. The lens ferritin content was analysed in two subjects who underwent cataract surgery at different ages, with different cataract morphology. Values were similar and about 1500‐fold higher than in controls. These observations suggest that: (i) in HHCS the cataract is not necessarily congenital; (ii) in addition to the IRE genotype, other genetic or environmental factors may modulate the phenotype, especially the severity of the cataract.

2 Juvenile haemochromatosis

Abstract Juvenile haemochromatosis (JH) is an autosomal recessive disorder which leads to earlyonset, 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.

A benign form of thalassaemia intermedia may be determined by the interaction of triplicated α locus and heterozygous β‐thalassaemia

In this paper we report that the combination of a triplicated α globin locus with heterozygous β‐thalassaemia produces a clinical phenotype of thalassaemia intermedia in five Italian subjects from four unrelated families, while in two other cases the phenotype was thalassaemia minor.

Rapid identification by denaturing gradient gel electrophoresis of mutations in the γ-globin gene promoters in non-deletion type HPFH

Summary We have outlined a fast, non‐radioactive strategy to identify point mutations in the 5’flanking region of the γ‐globin genes using denaturing gradient gel electrophoresis (DGGE) of amplified DMA. In a sample of previously characterized carriers of non deletion‐type hereditary persistence of fetal haemoglobin (HPFH) the different point mutations in both γ gene promoters could be easily identified by DGGE of a 327 bp fragment. A 4 bp deletion at position —225 to —222 of the Aγ globin gene was unexpectedly found in several samples and shown to represent a frequent polymorphism.

Clinical and Haematological Data in 254 Cases of Beta-Thalassaemia Trait in Italy

The haematological and clinical data in 254 Italian subjects with β‐thalassaemia trait are reported. 46% of the patients were anaemic, 40% complained of weakness, 19% showed enlargement of the spleen and 10% enlargement of the liver. The haemoglobin levels ranged from 8 to 15.5 g/dl with a normal distribution and a mean of 12.73 for males, 10.93 for females and 11.34 for children (4–15 years). Reticulocyte counts and serum bilirubin levels were slightly increased and both showed a statistically significant relationship with haemoglobin levels. The serum iron level was increased in 27% and decreased in 6% of the cases. Haemoglobin A2 concentrations ranged from 3.5 to 8% with a normal distribution and a mean of 5.37; Hb F values were less than 1% in 36% and varied from 1 to 14% in the remainder. Red cell osmotic fragility was decreased in all but 6% of the subjects: low MCV, MCH and MCHC values were observed in 75%, 86% and 10% respectively. A comparison is made between the data and those obtained by other workers.

New polymorphisms and markers in the HLA class I region: relevance to hereditary hemochromatosis (HFE).

Hereditary hemochromatosis (HFE) is an inherited disorder whose gene lies in the proximity of the histocompatability antigen (HLA) class I region, on 6p21.3. Despite efforts in refining the HFE region, a number of informative DNA markers, linked to the disease locus and amenable to use in an assay based on the polymerase chain reaction (PCR) is available. The gene content of this region is high, and the HFE gene has not so far been identified. We have used a strategy based on PCR protocols potentially able to detect both polymorphisms and expressed sequences. This approach has been applied to a 700-kb stretch (approximately) of DNA corresponding to the insert of a Centre dEtude du Polymorphisme Humain yeast artificial chromosome (225 B1) of the possible candidate region. Five new polymorphisms have been detected among 20 specific fragments isolated. Four of them are tightly linked to the HFE locus. Because of the strong linkage disequilibrium with the disease demonstrated by these markers, they could represent starting points for the identification and characterization of the HFE gene. The remaining non-polymorphic fragments, being amplifiable and in most cases linked to NotI sites, may be useful starting points for the generation of a genomic contig of band 6p21.3 and for gene identification.