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Biomedical subjects

M Lovicu

Publications and source records attributed to M Lovicu.

15 recordsLinked to original sources
PubMed2002

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.

Adenosine Triphosphatases↗
PubMed2000

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.

Adenosine Triphosphatases↗
PubMed1999

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.

Adult↗
PubMed1999

Molecular characterization of wilson disease in the Sardinian population--evidence of a founder effect.

Wilson disease (WD) in the Sardinian population has an approximate incidence of 1:7,000 live births. Mutation analysis of the WD gene in this population reported in our previous articles led us to the characterization of two common mutations and a group of 13 rare mutations accounting for the molecular defect of 8.5, 7.9, and 15.1% of the WD chromosomes. However, molecular analysis of the WD chromosomes containing the most common haplotype, which accounts for 60.5% of the WD chromosomes, failed to define the disease-causing mutation. In this study, we characterized the promoter and the 5' UTR of the WD gene sequence and carried out a mutation analysis in this DNA region from patients with the most common haplotype. The promoter is contained in a GC-rich island and shows a TATA and a CAAT consensus sequence as well as potential binding sites for transcription factors and metal response elements. In all the analyzed 92 chromosomes with this haplotype, we detected a single mutation consisting of a 15-nt deletion from position -441 to position -427 relative to the translation start site. Expression assays demonstrated a 75% reduction in the transcriptional activity of the mutated sequence compared to the normal control. By adding this mutation to those that have been already characterized, we have now defined the molecular defect in 92% of the WD chromosomes in Sardinians. The high frequency, the expected prevention by preclinical diagnosis and early treatment of the devastating effect of WD on the nervous system and liver tissue, and the feasibility to detect most of molecular defects by DNA analysis indicate that WD in the Sardinian population should be added to the list of diseases currently detected by newborn screening.

5' Untranslated Regions↗
PubMed1999

Mutation analysis in patients of Mediterranean descent with Wilson disease: identification of 19 novel mutations.

In this study, we report further results of mutation analysis of the ATP7B gene in Wilson disease (WD) patients of Mediterranean origin. A total of 136 WD chromosomes, 73 of which were of Italian, 43 of Turkish, 18 of Sardinian, and two of Spanish origin, were analysed and the mutation characterised in 84.5% of them. We found 50 different mutations of which 19 are novel, including three nonsense, one frameshift, and 15 missense mutations. The mutations detected were rare and mostly found in the compound heterozygous state together with other mutations and only rarely in homozygosity. Most of these mutations lie in the transmembrane and ATP binding loop regions. These data expand our knowledge of both the structure-function relationships of the WD protein and the molecular pathology of WD, thus improving our capability of prevention and genetic counselling.

Adenosine Triphosphatases↗
PubMed1998

Further delineation of the molecular pathology of Wilson disease in the Mediterranean population.

This study presents the update results of an ongoing project on the delineation of the spectrum of mutations at the Wilson disease (WD) gene in WD patients of Mediterranean origin. In studying 59 patients, of whom were 26 Continental Italians, 22 Sardinians, 9 Turkish, and 2 Albanians, we have found 31 novel and three known mutations. Of the novel mutations, 3 are deletions, two nonsense, 2 splice or consensus splice site, and 24 missense. The large majority of the missense mutations lie in evolutionary conserved regions of the WD gene of documented functional importance. Most of our patients were compound heterozygotes, and only a few were homozygotes. In addition, three polymorphisms were detected. By adding the new data to those previously reported by our group, we have to date detected 85% of mutations in the WD chromosomes from Continental Italians, 30% from Sardinians, 81.7% from Turkish and 66.7% from Albanians. Most of the mutations characterized are rare, and only a limited number are common. Of the common mutations 5 were found in Continental Italians, two in Sardinians and a single one in Turkish. Because there are so many causative mutations of the disease, the preclinical and prenatal diagnosis of WD should be carried out by a combination of mutation and linkage analysis.

Adenosine Triphosphatases↗
PubMed1998

Early and severe neurological features in a Wilson disease patient compound heterozygous for two frameshift mutations.

UNLABELLED: We describe a patient with Wilson disease who presented at 11 years of age with neurological symptoms and subsequent rapid progression of neurological impairment but absent hepatic manifestations. Molecular analysis showed compound heterozygosity for two frameshift mutations, 2299insC and 214delAT, which most likely result in an absent or inactive protein product. Mutation-phenotypic analysis indicates that this genotype does not explain the severe phenotype, suggesting the presence of modifying factors. CONCLUSION: Wilson disease may present even in childhood or adolescence with neurological abnormalities in the absence of hepatic manifestations.

Child↗
PubMed1996

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.

Albania↗
PubMed1995

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.

Albania↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

Molecular and biochemical data on some glucose-6-phosphate dehydrogenase variants from southern Sardinia.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD; E.C.1.1.1.49) deficiency is the most common human enzymopathy; nearly 400 different biochemical variants of the enzyme have been described. Sardinia is the Italian region with the highest frequency of this defect. METHODS: We examined genomic DNA of 16 subjects with G6PD Mediterranean, 2 with G6PD Athens-like, 1 with G6PD Ferrara 2 (all as biochemically defined). RESULTS: All G6PD Mediterranean subjects had a C-->T mutation at nucleotide 563 and a C-->T transition at nucleotide 1311; G6PD Athens-like and Ferrara 2 subjects had a G-->C mutation at nucleotide 844 (the same mutation has been found in G6PD Seattle-like). CONCLUSIONS: This study suggests that in Southern Sardinia G6PD mutations are relatively homogeneous and that the results of biochemical characterization studies must be carefully evaluated, because the same mutations might be responsible for different biochemical behavior.

Genetic Variation↗