Abnormal mRNA splicing resulting from consensus sequence splicing mutations of ATP7B.

More than 200 Wilson disease (WD) disease-causing mutations have been defined to date. Missense mutations are largely prevalent while splice-site mutations are limited in number. Most reside in the splice donor or acceptor sites and only a minority are detected in splicing consensus sequences. Furthermore, only a few splicing mutations have been studied at the RNA level to date. In this study, using the RT-PCR method we performed the molecular characterization of four consensus splice-site mutations identified by DNA analysis in patients with WD. One of them, previously described 1707+3insT, occurred at position 3 in the donor splice site of intron 4, while the other three, 2122-8T>G, 2866-6T>G, and 3061-12T>A, are novel and occurred in the acceptor splice sites of introns 7, 12, and 13, respectively. Analysis revealed a prevalently abnormal splicing in the samples carrying the mutations compared to the normal controls. Comparison of RNA splicing with normal controls in liver and lymphocytes further suggests that abnormal splicing of the WD gene is also present and differentially regulated in normal tissues. The results produced in this study strongly suggest that DNA mutations residing in the consensus sequence of WD gene splice sites result in the WD phenotype by interfering with the production of the normal WD protein. Further studies are necessary to better quantify the amount of different transcripts produced by these mutations, and establish their correlation with the disease phenotype.

Haplotype and mutation analysis in Greek patients with Wilson disease.

In this study, we report the results of haplotype and mutation analysis of the ATP7B gene in Wilson disease (WD) patients of Greek origin. We have analysed 25 WD families and two single patients and characterised 94% of the WD chromosomes investigated. We have found 12 different molecular defects (three frameshifts, two splice site, two nonsense, five missense mutations), four of which are novel. Five of the mutations are widely prevalent accounting for 74% of the WD chromosomes analysed. These results may enable preclinical diagnosis in the large majority of WD patients of Greek descent, thereby improving genetic counselling and disease management.

Detection of a rare Wilson disease mutation associated with arylsulfatase A pseudodeficiency.

We have studied a patient with Wilson disease (WD), belonging to a family segregating late-onset, dominant cerebellar ataxia. Analysis of the WD gene showed that the patient is a compound heterozygote, carrying the 14His1069Gln mutation from the father and the 8Gly710Ser mutation from the mother. The 8Gly710Ser is a mutation described previously only in a Swedish patient. Our patient is also homozygous for arylsulfatase A pseudodeficiency. This genetic defect, which has been reported in association with other neuropsychiatric syndromes, has not been described in WD.

Molecular analysis of atypical beta-thalassemia heterozygotes.

This paper reviews the molecular pathology of a heterogeneous group of beta-thalassemia heterozygotes which may be referred to as atypical beta-thalassemia. This group includes four different categories of heterozygous beta-thalassemia, which are characterized, respectively, by (1) normal MCV and MCH; (2) normal Hb A2; (3) normal MCV, MCH, and Hb A2 and imbalanced globin chain synthesis only or, (4) the presence of clinical manifestations. The first group is represented by a limited proportion of double heterozygotes for alpha- and beta-thalassemia. The second group includes two categories. One category is double heterozygotes for delta- and beta-thalassemia with the delta-thalassemia mutation in cis or in trans to beta-thalassemia. A number of delta-thalassemia mutations which produce this phenotype by interacting with beta-thalassemia have been described. The other category within the second group is heterozygotes for some mild beta(+)-thalassemia mutations. Within the third group, conclusive evidence for a mutation within the beta-globin gene cluster producing the silent beta-thalassemia phenotype has been obtained solely for a C----T substitution at -101 within the CACCC box of the beta-globin gene. Possible candidates are the complex rearrangements (-T, +ATA; -T, +ATATA) found at position -530 from the cap site. In the group of thalassemic hemoglobinopathies, a series of mutations mostly located in the third exon and producing elongated or truncated molecules have been recently reported. Most of the mutations are silent at the protein level, produce inclusion bodies in peripheral erythrocytes, and show a dominant transmission pattern or occur sporadically.

Delineation of the spectrum of Wilson disease mutations in the Greek population and the identification of six novel mutations.

In this study, we report the further results of an ongoing project on the delineation of the spectrum of mutations on the ATP7B gene in Wilson disease (WD) patients of Greek origin. We have analyzed 24 additional families and detected 16 mutations (five frameshifts, two splice site, two nonsense, and seven missense), of which six are novel. On adding these results to the ones already published by us, we conclude that WD shows a marked allelic heterogeneity in the Greek population. Of the total number of mutations so far detected, the most common eight account for the molecular defect in 72.8% of the WD chromosomes. The most frequent mutation is the His0169Gln, which has a frequency of 28.5%, similar to those reported in North European populations. Using these data, an efficient strategy of mutation screening for WD is possible in this population, thus improving the possibility of preclinical diagnosis.

Acute Gallbladder Hydrops and Arthritis: unusual initial manifestations of Wilson's Disease (WD): Case Report.

Wilson disease (WD) is an autosomal recessive disorder, in which copper is deposited in the liver, brain, cornea and kidneys. The clinical presentation is variable, with fully expressed disease manifesting cirrhosis, neurologic damage and Kayser-Fleischer (K-F) ring on the cornea. A 24-year-old patient developed right upper quadrant pain with a palpable mass and a swelling of the right talocrural articulation. X-rays were uneventful, but the routine examination of hepatic enzymes discovered a 6-8 fold increase in SGPT, SGOT and AST. Antibodies for hepatitis B, C were normal, as well as the ANA, ANCA, antimytochondrial and anti-smooth muscle antibodies. Ultrasound of the abdomen revealed extremely dilated hepatic, cystic ducts as well as gallbladder. A large, oedematous gallbladder with yellow green bile was removed, the liver was found to be cirrhotic, but as the operative bleeding was abundant a biopsy was not done. Serum ceruloplasmin was low [0.160 g/l (normal 0.204-0.407)], serum copper 12.7 µmol/l (11.0-24.4), transaminasis: always very high, in the last months normal/slightly elevated. Urine copper: 1.0 µmol/24 h (>9.44). As first seen the proband had tremor, dysarthria, dystonia and K-F ring on the cornea. After 10 months of treatment with penicillamine his transaminases normalized, the tremor, dysarthria, dystonia initially got worse and then ameliorated. The coagulation times are ameliorated, but not yet normalized. Mutational analysis has shown that the proband is homozygote for c.3207 C->A, p.H1069Q while his parents are heterozygotes. His sister is a healthy non-carrier. In brief, we describe an unusual presentation of WD, with gallbladder hydrops and talocrural arthritis in a patient with complete clinical manifestations of the disease.

Feasibility of prenatal diagnosis of beta-thalassemia using two highly polymorphic microsatellites 5' to the beta-globin gene.

Short tandem repeats (STRs) are highly informative loci within the human genome, consisting of short nucleotide sequences tandemly repeated in variable numbers. This results in different alleles of variable length. Herein we describe two STRS located 5' to the beta-globin gene. They can be detected by non radioactive methods and may be used to make prenatal diagnosis of beta-thalassemia.

Wilson's disease.

Wilson's disease is an autosomal recessive disorder of copper metabolism resulting from the absence or dysfunction of a copper transporting P-type ATPase encoded on chromosome 13. This ATPase is expressed in hepatocytes where it is localized to the trans-Golgi network and transports copper into the secretory pathway for incorporation into ceruloplasmin and excretion into the bile. Under physiologic circumstances, biliary excretion represents the sole mechanism for copper excretion, and thus affected individuals have progressive copper accumulation in the liver. When the capacity for hepatic storage is exceeded, cell death ensues with copper release into the plasma, hemolysis, and tissue deposition. Presentation in childhood may include chronic hepatitis, asymptomatic cirrhosis, or acute liver failure. In young adults, neuropsychiatric symptoms predominate and include dystonia, tremor, personality changes, and cognitive impairments secondary to copper accumulation in the central nervous system. The laboratory diagnosis of Wilson's disease is confirmed by decreased serum ceruloplasmin, increased urinary copper content, and elevated hepatic copper concentration. Molecular genetic analysis is complex as more than 100 unique mutations have been identified and most individuals are compound heterozygotes. Copper chelation with penicillamine is an effective therapy in most patients and hepatic transplantation is curative in individuals presenting with irreversible liver failure. Elucidation of the molecular genetic basis of Wilson's disease has permitted new insights into the mechanisms of cellular copper homeostasis.

Normal delta-globin gene sequences in Sardinian nondeletional delta beta-thalassemia.

In order to clarify the reasons for the reduced Hb A2 levels in Sardinian delta beta-thalassemia, we characterized, both by cloning and sequence analysis and by direct sequencing of amplified DNA, the delta-globin gene from an individual of Sardinian descent who is a compound heterozygote for the beta zero-thalassemia codon 39 (C-->T) nonsense mutation and the Sardinian delta beta-thalassemia [codon 39(C-->T)/-196(C-->T)A gamma]. The analysis of the delta-globin gene from the delta beta-thalassemia chromosome revealed an entirely normal sequence. The defective function of the delta-globin gene in this determinant is thus likely related to a suppressive effect of the in cis nondeletional high persistence of fetal hemoglobin mutation of the A gamma gene, probably resulting from an increased capability of the relative promoter to interact with the locus control region.

Wilson's disease with Leu492Ser mutation and arylsulfatase A pseudodeficiency: just a coincidence?

Wilson's disease (WD) is an autosomal recessive disorder of copper transport, related to mutations of the ATP7B gene (McKusick 277900). Here we report a new case of WD in which a rare mutation, Leu492Ser expressed for the first time in homozygosity, is associated with neurological presentation of the disease and arylsulfatase A pseudodeficiency.

A novel Mediterranean "delta beta-thalassemia" determinant containing the delta (+) 27 and beta (0) 39 point mutations in cis.

The term delta beta-thalassemia with normal HbF has been recently proposed to define heterogenous delta and beta globin gene molecular defects involving the same chromosome in cis. Here, we describe a Sardinian family in which three members showing microcytosis, border-line HbA2 levels and normal HbF proved to be heterozygotes for delta(+) 27 and beta(0) 39 point mutations in cis by allele specific oligonucleotide hybridization as well as by ECO 0 109 I endonuclease digestion and electrophoresis. As some of these beta-thalassemia carriers shows normal HbA2 levels, knowledge of the molecular basis of this novel delta beta-thalassemia silent phenotype would be useful in thalassemia screening and genetic counselling.

A beta-thalassaemia phenotype not linked to the beta-globin cluster in an Italian family.

This paper describes a family of Central Italian origin in which three patients in two generations had either thalassaemia intermedia or a late presenting form of thalassaemia major. Sequence analysis of the patients' DNA revealed that only one of the beta-globin genes was affected by a beta-thalassaemia mutation (the codon 39 nonsense mutation), the other being completely normal, apart from the complex rearrangement (-T +ATA) at position -530 5' to the CAP site of the beta-globin gene, which has uncertain clinical significance. Haematologically, all these patients were characterized by unusually low HbF levels (1.8-7.3%) for a beta-thalassaemia major or intermedia phenotype. The mother of the two patients with thalassaemia intermedia was heterozygous for beta-thalassaemia (codon 39 nonsense mutation), while the father had thalassaemia-like red cell indices, an increased alpha/non alpha chain synthesis ratio, a slight increase of HbF and a low HbA2 level, but showed entirely normal beta-globin gene sequences, apart from the complex rearrangement (-T +ATA) at position -530 5' to the CAP site. One of the thalassaemia intermedia patients married a normal woman and they had a child with thalassaemia major who inherited only the codon 39 nonsense mutation but not the complex rearrangement at position -530. The clinical phenotype of thalassaemia-intermedia or major in the patients from this family may be explained by postulating the inheritance of the double heterozygous state for beta-thalassaemia and for a mutation in a gene coding for an erythroid-specific DNA binding protein which may impair the function of the normal beta-globin gene. Heterozygosity for this postulated mutation (father of the patients with thalassaemia intermedia) may result in the production of a beta-thalassaemia carrier state with normal HbA2 level.

Molecular characterization of beta-thalassemia intermedia in patients of Italian descent and identification of three novel beta-thalassemia mutations.

In this study, we have defined by dot-blot analysis with allelic specific oligonucleotide probes or direct sequencing on amplified DNA the beta-thalassemia mutations in a large group of patients (23) of Italian descent with thalassemia intermedia. These patients had one parent with either the silent beta-thalassemia carrier phenotype or borderline-normal hemoglobin A2 (HbA2) levels (2.5% to 3.5%). Nearly all were genetic compounds for a severe beta-thalassemia mutation and a beta-thalassemia mutation associated with high residual output of beta-globin chains (beta + intervening sequence [IVS]-I-nt6, beta -87, beta -101), indicating that inheritance of a mild beta-thalassemia allele, even in a single dose, is the most common molecular mechanism producing thalassemia intermedia in the Italian population. In three cases, in whom we failed to define by dot-blot analysis the mutations, we sequenced the beta + globin gene and found three novel beta-thalassemia mutations, which are certainly very rare because they have been hitherto detected solely in a single patient. These mutations consist of: (1) a T-A substitution at position 2 of IVS-I, in a patient compound heterozygote for this mutation and the -87 promoter mutation; (2) a G-C substitution at position 844 of IVS-II, in a patient heterozygous for this mutation who showed normal sequences at the in trans beta-globin gene (The reason for the presence of clinical manifestations in a beta-thalassemia heterozygote has not been defined.); and (3) a deletion of one nucleotide (-T) at codon 126, resulting in a frameshift and readthrough of the 5' untranslated region and most likely producing an elongated Hb molecule of 156 amino acid residues, in a patient heterozygous for this mutation with normal beta-globin gene sequences at the other locus.

Delta-thalassemia due to a mutation in an erythroid-specific binding protein sequence 3' to the delta-globin gene.

We have previously described a family of Northern Sardinian descent in which the propositus was affected by thalassemia major resulting from compound heterozygosity for codon 39 nonsense mutation and the beta +IVS II nt 745 mutation and in which all heterozygotes for the beta +IVS II nt 745 mutation had normal hemoglobin (Hb) A2 levels. To define the reasons for normal HbA2 levels in otherwise typical beta-thalassemia heterozygotes, we cloned and sequenced the delta-thalassemia gene in cis to the beta +IVS II nt 745 mutation. The sequence analysis showed a single nucleotide substitution (G----A) at position 69 nts (delta +69) downstream to the polyA addition site. Dot blot analysis with an oligonucleotide probe complementary to the delta +69 mutation detected this mutation in several heterozygotes for the beta +IVS II nt 745 mutation from the proband's family, but failed to show it either in a group of normal individuals of the same origin or in nonrelated heterozygotes for the beta +IVS II nt 745 mutation of the same or different descent from the proband. The delta +69 (G----A) mutation may be responsible for the low delta-globin output from the beta +IVS II nt 745 chromosome or could be a silent polymorphism not affecting the function of the delta-globin gene. The normal G at position 69 is part of a sequence very similar to the core DNA (A/T)GATA(A/G) motif (GATA box) that is a binding site for the GATA-1 protein. Gel-retardation assay has shown that a DNA fragment containing the GATA motif with the G----A at position +69 has increased binding affinity for erythroid-specific DNA binding protein(s) as compared with the wild-type sequence. These findings may suggest that the delta +69 mutation is responsible for the deficient function of the in cis delta-globin gene.

Molecular pathology and haplotype analysis of Wilson disease in Mediterranean populations.

We analyzed mutations and defined the chromosomal haplotype in 127 patients and Mediterranean descent who were affected by Wilson disease (WD), 39 Sardinians, 49 Italians, 33 Turks, and 6 Albanians. Haplotypes were derived by use of the microsatellite markers D13S301, D13S296, D13S297, and D13S298, which are linked to the WD locus. There were five common haplotypes in Sardinians, three in Italians, and two in Turks, which accounted for 85%, 32%, and 30% of the WD chromosomes, respectively. We identified 16 novel mutations: 8 frameshifts, 7 missense mutations, and 1 splicing defect. In addition, we detected the previously described mutations: 2302insC, 3404delC, Arg1320ter, Gly944-Ser, and His1070Gin. Of the new mutations detected. two, the 1515insT on haplotype I and 2464delC on haplotype XVI, accounted for 6% and 13%, respectively, of the mutations in WD chromosomes in the Sardinian population. Mutations H1070Q, 2302insC, and 2533delA represented 13%, 8%, and 8%, respectively, of the mutations in WD chromosomes in other Mediterranean populations. The remaining mutations were rare and limited to one or two patients from different populations. Thus, WD results from some frequent mutations and many rare defects.

Improvement of prenatal diagnosis of Wilson disease using microsatellite markers.

This paper describes a case of prenatal diagnosis for Wilson disease (WD) carried out in an at-risk couple of Sardinian descent, following non-directive genetic counselling. Diagnosis was obtained by using eight microsatellites located within or flanking the WD locus, six of which were 100 per cent and two 50 per cent informative. The use of several markers may limit the occurrence of misdiagnosis resulting from recombination or instability of repeats.

Wilson disease mutations associated with uncommon haplotypes in Mediterranean patients.

This study reports 12 novel mutations of the Wilson disease (WD) gene which have been detected by the molecular analysis of 29 patients of Mediterranean descent carrying uncommon chromosomal haplotypes at the WD locus. These mutations include two nonsense, one splice site and nine missense. The missense mutations lie in regions of the WD gene critical for its function, such as the transmembrane region, the transduction domain and the ATP loop and ATP-binding domain, indicating that they are disease-causing mutations. These new findings improve our knowledge for the role played by functional domains on the ATP7B function.

Use of the stable isotope 65Cu test for the screening of Wilson's disease in a family with two affected members.

BACKGROUND/AIMS: An improved method for the study of copper metabolism in Wilson's disease, using a stable, rather than radioactive, copper isotope (65Cu) has recently been described. We report on the use of this method for the study of a family with two members affected by Wilson's disease. SUBJECTS: The family comprised parents and four siblings: one 20-year-old male and three females, aged 22, 17 and 5 years, respectively. The boy and the 17-year-old girl both presented with liver cirrhosis. Diagnosis of Wilson's disease was suggested by elevated liver copper content and/or low caeruloplasmin levels and Kayser-Fleischer ring. METHODS: All family members were given an oral dose of 3 mg of 65Cu. Blood samples were taken at 0, 1, 2, 6, 24, 48, and 72 hours. In 4 subjects, additional blood samples were drawn at 7, 14 and 21 days after dosage. The ratio 65Cu:63Cu in serum was determined in all samples by means of Inductively Coupled Plasma Mass Spectrometry. RESULTS: The diagnosis of Wilson's disease was confirmed in the two symptomatic members by the unequivocal decrease observed in the 65Cu percent enrichment, which approached zero by 72 hours. In contrast, Wilson's disease could be definitely excluded in both siblings, one of whom only 5 years old, on the evidence of net secondary peaks, showing normal incorporation of 65Cu into caeruloplasmin. These findings were later confirmed by genetic analysis. Parents, who carried defective genes with different mutations, also showed different abnormalities of copper metabolism. CONCLUSIONS: The oral test with the stable copper isotope 65Cu is a safe, non invasive option able to exclude Wilson's disease in patients with a difficult diagnosis or in a presymptomatic stage. However, positive tests must still be confirmed by copper dosage in liver biopsies, as heterozygotes can present with severe alterations of copper metabolism, without developing symptoms of the disease. The use of this test in conjunction with genetic analysis on a larger number of heterozygous subjects may add to the understanding of the Wilson's disease defect.

Reliability of prenatal diagnosis of genetic diseases by analysis of amplified trophoblast DNA.

Dot blot analysis on enzymatically amplified trophoblast DNA with allele specific oligonucleotide probes is currently used for the prenatal diagnosis of single gene disorders characterised at the molecular level, such as the beta thalassaemias, phenylketonuria, sickle cell anaemia, and alpha 1-anti-trypsin deficiency. A potential problem with the use of this procedure is the co-amplification of maternal sequences, which may obscure the diagnosis in the fetus. To address this question, we carried out prenatal diagnosis of beta thalassaemia in 300 couples at risk by dot blot analysis on enzymatically amplified DNA with 32P or horseradish peroxidase labelled allele specific oligonucleotide probes. We verified the diagnosis obtained by this procedure with oligonucleotide hybridisation on electrophoretically separated non-amplified trophoblast DNA fragments. We detected no co-amplified maternal sequences, even with a faint signal, in the dot blot of trophoblast DNA from those fetuses diagnosed as normal or homozygotes, nor in those diagnosed as heterozygotes, who were born to parents carrying different mutations and had inherited the paternal mutation. These results indicate that, when careful dissection of trophoblast tissue from maternal decidua is carried out, amplification of chorionic villi DNA is not associated with amplification of maternal DNA sequences. We may thus conclude that dot blot analysis of trophoblast DNA is a very reliable procedure for prenatal diagnosis.

The C-T substitution in the distal CACCC box of the beta-globin gene promoter is a common cause of silent beta thalassaemia in the Italian population.

This paper describes four families of Italian descent in each of which the propositus had the clinical phenotype of thalassaemia intermedia, resulting from the compound heterozygous state for high HbA2 beta thalassaemia and type I silent beta thalassaemia. Direct sequencing on amplified DNA and/or oligonucleotide analysis detected, in all families but one, the compound heterozygous state for codon 39 nonsense mutation and the C-T substitution at position -101 in the distal CACCC box of the beta-globin gene promoter (beta th-101). Members of these families who are heterozygous for high HbA2 beta thalassaemia showed the codon 39 nonsense mutation, while those with the clinical phenotype of silent beta thalassaemia had the beta th-101 mutation. In the remaining family, the propositus and one of his siblings had the compound heterozygous state for a molecularly undefined high HbA2 beta thalassaemia and the beta th-101 mutation in combination with the triple alpha globin gene arrangement. These patients showed a more severe thalassaemia intermedia like clinical phenotype as compared to those with the same beta-globin genotype and a normal alpha-globin gene arrangement. In the families investigated the beta th-101 was always associated with haplotype I. A group of patients with thalassaemia intermedia from Southern Italy, either homozygous or heterozygous for haplotype I and in whom previous studies had failed to define the mutation in one of the beta thalassaemia globin genes, were screened by oligonucleotide analysis for the presence of the beta th-101. Three out of nine were positive. These results indicate that the beta th-101 mutation is a common cause of the type I silent beta thalassaemia phenotype in the Southern Italian population.