Biomedical subjects

P Rizzu

Publications and source records attributed to P Rizzu.

12 recordsLinked to original sources

PubMed1997

Delineation of a duplication map of chromosome 3q: a new case confirms the exclusion of 3q25-q26.2 from the duplication 3q syndrome critical region.

We report on the clinical, cytogenetic, and molecular characterization of a propositus and his mother with a duplication of 3q25-q26, minor anomalies, and mental retardation. The duplication, detected by cytogenetic analysis, was confirmed and delineated by comparative genomic hybridization and fluorescence in situ hybridization using probes previously mapped to the region. Comparison of the mapping data obtained in these patients and those obtained in patients that present with a typical dup(3q) syndrome phenotype shows that the segment duplicated in these patients lies proximally to the reported dup(3q) syndrome critical region, thus explaining the absence in our patients of the characteristic phenotype of dup(3q) syndrome patients. Accumulation of mapping data in patients with segmental duplications of 3q will eventually allow us to build a duplication map of the region and a genotype-phenotype correlation.

Adolescent↗

PubMed1997

Hereditary frontotemporal dementia is linked to chromosome 17q21-q22: a genetic and clinicopathological study of three Dutch families.

Hereditary frontotemporal dementia (HFTD) is a rare autosomal dominant form of presenile dementia characterized by behavioral changes and reduced speech. Three multigeneration kindreds with this condition, in the Netherlands, were investigated for clinicopathological comparison and linkage analysis. Frontotemporal atrophy on computed tomographic scanning and/or magnetic resonance imaging was usually present. Single-photon emission computed tomography (SPECT) showed frontal hypoperfusion in the early phase of the disease. Brain tissue showed moderate to severe atrophy of frontal and temporal cortex with neuronal loss, gliosis, and spongiosis. Pick bodies were lacking in all cases of the 3 families. The mean age of onset varied significantly between families. We report here evidence for linkage to chromosome 17q21-q22 with a maximum lod score of 4.70 at theta = 0.05 with the marker D17S932. Recombination analysis positions the gene for HFTD in a region of approximately 5 cM between markers D17S946 and D17S791. Three other neurodegenerative disorders with a strong clinical and pathological resemblance have recently been mapped to the same chromosomal region, suggesting that a group of clinically related neurodegenerative disorders may originate from mutations in the same gene.

Chromosomes, Human, Pair 17↗

PubMed1996

A transcription map in the CATCH22 critical region: identification, mapping, and ordering of four novel transcripts expressed in heart.

The acronym CATCH22 is used to indicate collectively a group of related phenotypes, namely velocardiofacial syndrome (VCFS), DiGeorge anomaly (DGA), and conotruncal anomaly face, which are associated with deletions within 22q11.2 in the great majority of patients. A deletion map has allowed us to delimit a smallest region of deletion overlap, considerably smaller than the commonly deleted region. We have mapped within this region the chromosomal breakpoint of a balanced translocation patient presenting with a DGA/VCFS phenotype, making this region the strongest candidate for the location of the gene(s) responsible for the disease phenotype. We report a systematic gene search in this region and show the presence of at least six distinct transcripts, two of which have been previously described. The region searched was approximately 270 kb; therefore, an average of one transcript every 45 kb was found. We generated eight new ESTs and mapped two ESTs present in public databases. All six transcripts are expressed in heart, an organ involved in 70%-80% of CATCH22 patients. We show that the multimethod approach to search for expressed sequences is effective and indeed necessary for a comprehensive search and provides molecular tools for further characterization of the potential genes identified.

Abnormalities, Multiple↗

PubMed1996

Cloning and comparative mapping of a gene from the commonly deleted region of DiGeorge and Velocardiofacial syndromes conserved in C. elegans.

We have identified and cloned a gene, ES2, encoding a putative 476 amino acid protein with a predicted Mr of 52,568. The gene is localized within the DiGeorge/Velocardiofacial syndrome locus on 22q11.2 and is deleted in all the patients in which a deletion within 22q11 could be demonstrated, with the exception of one patient. ES2 is expressed in all the tissues studied. Sequence comparison showed identity with five ESTs and at the amino acid level the sequence was highly similar to, and collinear with, a hypothetical C. elegans protein of unknown function. Mutation analysis was performed in 16 patients without deletion, but no mutation has been found. The cDNA sequence is conserved in mouse and is localized on MMU16B1-B3, known to contain a syntenic group in common with HSA 22q11.2.

Abnormalities, Multiple↗

PubMed1995

Duplication 3q syndrome: molecular delineation of the critical region.

The phenotype of dup(3q) syndrome partially overlaps with Brachmann-de Lange phenotype. Convulsions and eye, palate renal, and cardiac anomalies are more frequent in dup(3q) syndrome, while limb deficiencies, hirsutism, and synophrys are more characteristic of Brachmann-de Lange syndrome. Whether the two syndromes have a biological relationship has yet to be demonstrated. Using two patient translocation cell lines, each involving distal 3q, we have narrowed the critical region of the dup(3q) syndrome to the interval 3q26.31-q27.3 and initiated its molecular characterization. We have mapped in this region 6 cosmid clones spanning approximately 3-5 Mb. The critical region appears to overlap with the region where a balanced translocation was found in a Brachmann-de Lange patient. This work provides the mapping framework for finer molecular analysis of dup(3q) syndrome.

Adult↗

PubMed1995

Three members of the human cystatin gene superfamily, AHSG, HRG, and KNG, map within one megabase of genomic DNA at 3q27.

While constructing a contig in the human chromosome region 3q27, we identified two YAC clones that were positive for the polymorphic marker D3S1602. One of these clones was also positive for a sequence-tagged site derived from the kininogen (KNG) gene. Because of the known evolutionary and structural relationship of KNG to other members of the cystatin gene superfamily, we tested the physical linkage of the genes encoding alpha-2HS-glycoprotein (AHSG), KNG, and histidine-rich glycoprotein (HRG), all of which were previously mapped to the long arm of chromosome 3. Our results show the colocalization of the three genes in two independent, partially overlapping YAC clones. The genomic inserts of the two clones were 1 Mb and 1.3 Mb in size, indicating that the three genes map within 1 Mb of DNA. The largest YAC was also positive for the polymorphic marker D3S1262, substantiating previously reported data of genetic linkage between this marker and HRG. Fluorescence in situ hybridization localized the two YAC clones to chromosome band 3q27.

Blood Proteins↗

PubMed1995

Mapping segmental imbalances using comparative genomic hybridization and eigenanalysis.

We have tested a new approach to comparative genomic hybridization (CGH) analysis using digital ratio images and eigenanalysis, which allows the recognition of consistent patterns along the chromosomes and discards random (background noise) patterns. We have performed test experiments using genomic DNAs from a patient with a duplication, another with a deletion of a chromosome segment, and a prostate cancer biopsy. Image ratio analysis was performed, and ratio images of the relevant chromosome were subjected to eigenanalysis. The results showed a high-contrast enhancement of the regions corresponding to the unbalanced genomic segment, with clearly defined limits between normal and abnormal fluorescence ratios. The combination of digital ratio images and eigenanalysis allowed the precise mapping of unbalanced regions consistent with other methods of analysis. Because there is no limit to the number of chromosomes that can be analyzed at any one time, the method has the potential of increasing the sensitivity of CGH by reducing the noise component.

Cell Line↗

PubMed1994

A species-specific DNA probe for the detection of Mycoplasma agalactiae.

A 4.5 kb M. agalactiae DNA fragment present in strains from different areas of Sardinia was cloned and used to detect M. agalactiae DNA in sheep milk samples by dot blot hybridization. The probe recognized only M. agalactiae strains and did not cross-hybridize with other mycoplasmas (M. capricolum, M. mycoides subsp. capri, M. mycoides subsp. mycoides, M. putrefaciens and M. arginini) or bacteria (E. coli, P. hemolytica, S. aureus, S. epidermis, L. casei, S. durans, S. lactis and S. thermophilus) which may also be found in sheep milk.

Animals↗

PubMed1994

Subchromosomal band interval mapping and ordering of DNA markers in the region 3q26.3-q27 involved in the dup(3q) syndrome.

The duplication 3q syndrome is characterized by the partial trisomy of a segment of the long arm of chromosome 3. This segment, although variable in size, includes 3q26.3-q27 as the minimal region of overlap. We have previously used patient chromosome breakpoints to select cosmids within this region. In this report, we have used two- and three-color fluorescence in situ hybridization on metaphase and interphase chromosomes to perform high-resolution cytological mapping of the six cosmids identified. The results allowed us to determine the centromere-telomere orientation, the order, and the relative distances of the markers used. Because some of the markers used are part of the consensus chromosome 3 map, our data can be easily integrated with existing mapping information about this chromosome. Our data provide a framework for further physical mapping studies of this region.

Abnormalities, Multiple↗

PubMed1994

A new method for identification of Trichomonas vaginalis by fluorescent DNA in situ hybridization.

The protozoan flagellate Trichomonas vaginalis is responsible for human trichomoniasis, one of the most widespread sexually transmitted diseases in the world. Several methods are currently used for laboratory diagnosis, including direct microscopic observation, cell culture, immunological techniques, and more recently, DNA probing and gene amplification. This report describes an in situ hybridization technique with specific DNA probes labeled with either biotin, rhodamine, or fluorescein for detection of T. vaginalis with fluorescence microscopy. Repetitive DNA sequences were evident in the nuclei of the protozoa as intensively fluorescent regions, giving a spotted pattern. No cross-reactivity between the probes and the DNAs of mammalian cells, yeasts, or bacteria was noted. This technique is potentially useful for the diagnosis of human trichomoniasis in clinical samples.

Animals↗

PubMed1993

TnphoA Salmonella abortusovis mutants unable to adhere to epithelial cells and with reduced virulence in mice.

Salmonella abortusovis is a pathogenic bacterium highly specific to sheep, causing spontaneous abortion. In order to understand the role of genes involved in pathogenicity, we investigated S. abortusovis with the random mutagenic TnphoA transposon. A total of 95 S. abortusovis TnphoA mutants yielding alkaline phosphatase active fusion protein were obtained. In this way we created a bank of strains in order to identify any phenotypic modification which could affect the periplasmic and/or exported proteins involved in virulence. The TnphoA mutants were screened for the ability to adhere to epithelial cells: a total of 23 mutant strains lost this phenotypic feature. To detect the chromosomal TnphoA insertions, DNA was restricted by the enzyme EcoRV, which does not cleave the TnphoA sequence. Southern blotting analysis revealed the existence of four classes of integration. Colonies of adhesiveless mutants appear to be as smooth as the S. abortusovis wild type, and electrophoretic analysis indicates a normal lipopolysaccharide profile. To identify mutations affecting genes encoding for outer membrane proteins (OMPs), the alkaline phosphatase portion of the fusion proteins was revealed in TnphoA mutants by immunoblotting with specific antibodies. A mutation in OMPs was detected in seven mutants. Restriction analysis identified in four mutants a common region of 2 kb where alterations in genes coding for OMPs occur. We suggested that this region is involved in pathogenicity in mice, since a group of mutant strains has shown reduced virulence in mice and one mutant is completely avirulent. Furthermore, after mice were exposed orally to these mutants, significant protection against oral challenge with the parental virulent strain resulted.

Abortion, Veterinary↗

PubMed1991

Molecular probe for identification of Trichomonas vaginalis DNA.

Trichomoniasis is one of the most widespread sexually transmitted diseases in the world. Diagnosis can be achieved by several methods, such as direct microscopic observation of vaginal discharge, cell culture, and immunological techniques. A 2.3-kb Trichomonas vaginalis DNA fragment present in strains from diverse geographic areas was cloned and used as a probe to detect T. vaginalis DNA in vaginal discharge by a dot blot hybridization technique. This probe was specific for T. vaginalis DNA. It recognized strains from two regions in Italy (Sardinia, Piemonte) and from Mozambique (Africa). In addition, our probe did not cross-react with bacterial (Escherichia coli, Enterococcus spp., group B streptococci, Gardnerella vaginalis, Neisseria gonorrhoeae, Chlamydia trachomatis, and Lactobacillus spp.), viral (herpes simplex virus type 2), fungal (Candida albicans), protozoan (Entamoeba histolytica, Giardia lamblia, Plasmodium falciparum, Leishmania major, and Leishmania infantum), or human nucleic acids. The probe reacted with Pentatrichomonas hominis and Trichomonas foetus. The limit signal recognized by our probe corresponded to the DNA of 200 T. vaginalis isolates. The 2.3-kb probe was used in a clinical analysis of 98 samples. Of these, 20 samples were found to be positive both with the probe and by cell culture, and only 14 of these were positive by a standard wet mount method.

Animals↗