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O Zuffardi

Publications and source records attributed to O Zuffardi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Opposite deletions/duplications of the X chromosome: two novel reciprocal rearrangements.

Paralogous sequences on the same chromosome allow refolding of the chromosome into itself and homologous recombination. Recombinant chromosomes have microscopic or submicroscopic rearrangements according to the distance between repeats. Examples are the submicroscopic inversions of factor VIII, of the IDS gene and of the FLN1/emerin region, all resulting from misalignment of inverted repeats, and double recombination. Most of these inversions are of paternal origin possibly because the X chromosome at male meiosis is free to refold into itself for most of its length. We report on two de novo rearrangements of the X chromosome found in four hypogonadic females. Two of them had an X chromosome deleted for most of Xp and duplicated for a portion of Xq and two had the opposite rearrangement (class I and class II rearrangements, respectively). The breakpoints were defined at the level of contiguous YACs. The same Xp 11.23 breakpoint was found in the four cases. That of the long arm coincided in three cases (Xq21.3) and was more proximal in case 4 (Xq21.1). Thus class I rearrangements (cases 1 and 2) are reciprocal to that of case 3, whilst that of case 4 shares only the Xp breakpoint. The abnormal X was paternal in the three cases investigated. Repeated inverted sequences located at the breakpoints of rearrangements are likely to favour the refolding of the paternal X chromosome and the recombination of the repeats. The repeat at the Xp11 may synapse with either that at Xq21.3 or that at Xq21.1. These rearrangements seem to originate as the Xq28 submicroscopic inversions but they are identifiable at the microscopic level and result from a single recombination event.

Adolescent↗
PubMed2000

Inverted duplications are recurrent rearrangements always associated with a distal deletion: description of a new case involving 2q.

We studied the case of a subject with an inverted duplication of 40 cM of 2q33-q37 concurrent with a 10 cM deletion of the distal 2q, the latter not being detectable by cytogenetics. Microsatellite analysis demonstrated the absence of maternal alleles in the deleted region and a double dosage for one of the maternal alleles in the duplication region. We hypothesised that this type of rearrangement occurs at meiosis I, while the two homologues are synapsed for most of their length. The presence of inverted duplicons in the same chromosome arm would favour the partial refolding of one homologue into itself so leading to the intrachromatid synapsis and recombination of the inverted repeats. The arising recombinant chromosome is deleted for the region beyond the most distal repeat and with the chromatids joined together at the level of the region located between the two duplicons. At meiosis II, the two linked chromatids can join the opposite poles provided that a breakage between the two centromeres occurs leading to a duplicated/deleted chromosome and a simply deleted chromosome. This model can be extended to all the so-called inverted duplication cases and to part of the terminal deletions. In fact the finding that, in our invdup(2q), the entire 40 cM duplication region involves only one of the two maternal alleles, indeed indicates that the abnormal crossover occurs between sister chromatids. The phenotype associated with our 2q rearrangement led us to narrow the critical region for the Albright-like syndrome to 10 cM in the subterminal 2q region.

Child↗
PubMed2000

Mapping of a human centromere onto the DNA by topoisomerase II cleavage.

We have mapped the positions of topoisomerase II binding sites at the centromere of the human Y chromosome using etoposide-mediated DNA cleavage. A single region of cleavage is seen at normal centromeres, spanning approximately 50 kb within the centromeric alphoid array, but this pattern is abolished at two inactive centromeres. It therefore provides a marker for the position of the active centromere. Although the underlying centromeric DNA structure is variable, the position of the centromere measured in this way is fixed relative to the Yp edge of the array, and has retained the same position for >100,000 years.

Cell Line↗
PubMed1999

Evidence for interaction between human PRUNE and nm23-H1 NDPKinase.

We have isolated a human and murine homologue of the Drosophila prune gene through dbEST searches. The gene is ubiquitously expressed in human adult tissues, while in mouse developing embryos a high level of expression is confined to the nervous system particularly in the dorsal root ganglia, cranial nerves, and neural retina. The gene is composed of eight exons and is located in the 1q21.3 chromosomal region. A pseudogene has been sequenced and mapped to chromosomal region 13q12. PRUNE protein retains the four characteristic domains of DHH phosphoesterases. The synergism between prune and awdK-pn in Drosophila has led various authors to propose an interaction between these genes. However, such an interaction has never been supported by biochemical data. By using interaction-mating and in vitro co-immunoprecipitation experiments, we show for the first time the ability of human PRUNE to interact with the human homologue of awd protein (nm23-H1). In contrast, PRUNE is impaired in its interaction with nm-23-H1-S120G mutant, a gain-of-function mutation associated with advanced neuroblastoma stages. Consistently, PRUNE and nm23-H1 proteins partially colocalize in the cytoplasm. The data presented are consistent with the view that PRUNE acts as a negative regulator of the nm23-H1 protein. We discuss how PRUNE regulates nm23-H1 protein and postulate possible implications of PRUNE in neuroblastoma progression.

Adult↗
PubMed1999

Identification and characterization of CDS2, a mammalian homolog of the Drosophila CDP-diacylglycerol synthase gene.

The general strategies of phototransduction in vertebrates and invertebrates share many similarities, but differ significantly in their underlying molecular machinery. The CDS gene encodes the CDP-diacylglycerol synthase (CDS) enzyme and is required for phototransduction in Drosophila. Using a bioinformatic approach, we have identified two novel transcripts (CDS1 and CDS2) highly homologous to the Drosophila CDS gene. We isolated and sequenced the CDS2 full-length cDNA and mapped the two genes to human chromosomes 20p13 (CDS2) and 4q21.1 (CDS1). Sequence analysis revealed that both genes are highly homologous to the Drosophila protein (64.4 and 58. 6% identity at the protein level between CDS and CDS2 and between CDS and CDS1, respectively). The mouse homologs for both genes were isolated and used in RNA in situ hybridization studies on adult and embryonic mouse tissue sections. These studies showed that Cds2 is highly expressed in the differentiating neuroblasts of the neural retina and in the central nervous system during embryonic development, while it was not detected in adult retina. Cds1, on the other hand, shows a high level of expression in the photoreceptor layer of adult retina, which strongly suggests a role for Cds1 in phototransduction. Knowledge of the expression pattern of these genes in mammals may shed light on the evolution of vision mechanisms and help in the evaluation of candidate genes for human retinopathies.

Adult↗
PubMed1999

Transmission of a fully functional human neocentromere through three generations.

An unusual Y chromosome with a primary constriction inside the long-arm heterochromatin was found in the amniocytes of a 38-year-old woman. The same Y chromosome was found in her husband and brother-in-law, thus proving that it was already present in the father. FISH with alphoid DNA showed hybridization signals at the usual position of the Y centromere but not at the primary constriction. Centromere proteins (CENP)-A, CENP-C, and CENP-E could not be detected at the site of the canonic centromere but were present at the new constriction, whereas CENP-B was not detected on this Y chromosome. Experiments with 82 Y-specific loci distributed throughout the chromosome confirmed that no gross deletion or rearrangement had taken place, and that the Y chromosome belonged to a haplogroup whose members have a mean alphoid array of 770 kb (range 430-1,600 kb), whereas that of this case was approximately 250 kb. Thus, this Y chromosome appeared to be deleted for part of the alphoid DNA. It seems likely that this deletion was responsible for the silencing of the normal centromere and that the activation of the neocentromere prevented the loss of this chromosome. Alternatively, neocentromere activation could have occurred first and stimulated inactivation of the normal centromere by partial deletion. Whatever the mechanism, the presence of this chromosome in three generations demonstrates that it functions sufficiently well in mitosis for male sex determination and fertility and that neocentromeres can be transmitted normally at meiosis.

Adult↗
PubMed1999

Identification of two paralogous regions mapping to the short and long arms of human chromosome 2 comprising LIS1 pseudogenes.

Reiner et al. (1995b) reported on the existence of a gene with a coding region virtually identical to LIS1, the gene responsible for Miller-Dieker lissencephaly. This gene, LIS2, was mapped to chromosome 2p11.2, and a related pseudogene, LIS2P, was mapped to 2q13-->q14. By sequencing genomic clones that were mapped by means of 2p and 2q-only hybrids, we now demonstrate the existence of two LIS1 processed pseudogenes mapping to 2p11.2 and 2q13 (PAFAH1P1 and PAFAH1P2, respectively). The two sequences appear to lie within larger paralogous regions and share a 98.6% degree of identity. Comparative mapping data by cytogenetic analysis on great apes indicate that the duplication of the genomic region comprising the LIS1 pseudogenes occurred in humans. We also demonstrate that the cDNA sequence shown as part of the LIS2 gene and marking its chromosome 2 specificity belongs to the 3' untranslated region of a different gene (C1orf6) that we mapped to 1q21 by FISH analysis.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1998

Characterization of Cxorf5 (71-7A), a novel human cDNA mapping to Xp22 and encoding a protein containing coiled-coil alpha-helical domains.

The human X chromosome is known to contain several disease genes yet to be cloned. In the course of a project aimed at the construction of a transcription map of the Xp22 region, we fully characterized a novel cDNA, Cxorf5 (HGMW-approved symbol, alias 71-7A), previously mapped to this region but for which no sequence information was available. We isolated and sequenced the full-length transcript, which encodes a predicted protein of unknown function containing a large number of coiled-coild domains, typically presented in a variety of different molecules, from fibrous proteins to transcription factors. We showed that the Cxorf5 cDNA is ubiquitously expressed, undergoes alternative splicing, and escapes X inactivation. Furthermore, we precisely mapped two additional Cxorf5-related loci on the Y chromosome and on chromosome 5. By virtue of its mapping assignment to the Xp22 region, Cxorf5 represents a candidate gene for at least four human diseases, namely spondyloepiphiseal dysplasia late, oral-facial-digital syndrome type 1, craniofrontonasal syndrome, and a nonsyndromic sensorineural deafness.

Alternative Splicing↗
PubMed1998

Genomic structure and chromosomal location of the human TGFbeta-receptor interacting protein-1 (TRIP-1) gene to 1p34.1.

The human TRIP-1 (transforming growth factor-beta (TGBbeta)-receptor interacting protein-1) cDNA encodes a protein able to associate specifically with the type II TGFbeta receptor. It is phosphorylated on serine and threonine by this receptor kinase which makes it a strong candidate as part of the TGFbeta signal transduction pathway. We have isolated the genomic sequence of TRIP-1 and found that the complete coding region is organised into 11 exons ranging from 39 to 397 bp and spanning approximately 9 kb of genomic DNA. The 5' flanking region lacks a TATA box but is GC-rich, suggesting that it is a constitutively expressed gene which is in agreement with its wide pattern of expression. Fluorescence in situ hybridisation mapped the TRIP-1 gene to chromosome 1p34.1 whereas a pseudogene is located on chromosome 7q32.

Chromosomes, Human, Pair 1↗
PubMed1998

The gene encoding a cationic amino acid transporter (SLC7A4) maps to the region deleted in the velocardiofacial syndrome.

By screening an expressed sequence tag database, we identified a novel human gene, SLC7A4, encoding a solute carrier family 7 [cationic amino acid (CAA) CAT-4 transporter, y+ system] member 4. The SLC7A4 cDNA is 2325 nt long and includes 78, 1911, and 336 nt in the 5' noncoding, coding, and 3'-noncoding regions, respectively. SLC7A4 displays high homology with SLC7A1 and SLC7A2, two previously known CAA transporters. By chromosomal in situ hybridization and YAC identification, SLC7A4 was mapped to 22q11.2, the commonly deleted region of the velocardiofacial syndrome (VCFS, Shprintzen syndrome). In a patient affected by VCFS, deletion of SLC7A4 was demonstrated by chromosomal FISH. By Northern analysis, an abundant transcript was detected in brain, testis, and placenta. Microinjection of SLC7A4 mRNA into Xenopus laevis oocytes demonstrates a significant stimulation of CAA transport.

Abnormalities, Multiple↗
PubMed1998

Human NRD convertase: a highly conserved metalloendopeptidase expressed at specific sites during development and in adult tissues.

We report the cloning of the human homologue of the rat metalloprotease N-arginine dibasic convertase (NRD convertase). This endopeptidase is responsible for the processing, at the Arg-Lys dibasic site on the N-terminal side of the arginine residue, of propeptides and proproteins. Comparisons of the human and rat full-length cDNAs show similarity and identity of 94 and 91%, respectively. In humans NRD convertase is predominantly expressed in heart, skeletal muscle, and testis. We have also studied the expression of this gene in mouse at various developmental stages and found that the neural tissue is the almost exclusive site of expression in early development (between E 10.5 and E 16.5). To gain information about the possibility that defects in this gene are linked to inherited neuromuscular disorders, we determined the chromosomal location of the human NRD convertase gene by FISH analysis, showing that the gene resides at 1p32.2.

Adult↗
PubMed1998

Human FIGF: cloning, gene structure, and mapping to chromosome Xp22.1 between the PIGA and the GRPR genes.

We report the identification, structural characterization, and mapping of the human FIGF gene. FIGF is the human homologue of mouse figf (c-fos-induced growth factor), a new member of the platelet-derived growth factor/vascular endothelial growth factor (PDGF/VEGF) family. It codes for a secreted factor with mitogenic and morphogenic activity on fibroblast cells. The predicted amino acid sequence of FIGF is 84% identical to that of the mouse protein, and it is highly conserved (up to 40%) in the dimerization domain with respect to the VEGF members of the family. The 2.5-kb mRNA of FIGF was detected in adult lung and heart tissues. The gene spans about 50 kb and is organized into seven exons and six introns. The FIGF promoter contains an optimal AP-1-binding site and lacks a canonical TATA box. Fluorescence in situ hybridization mapped FIGF to chromosomal region Xp22.1. The subsequent identification of YAC positive clones from this region allowed us to refine the map and localize FIGF centromeric to the phosphatidylinositol glycan complementation class A (PIGA) gene and telomeric to the gastrin-releasing peptide receptor (GRPR) gene. FIGF and PIGA genes lie next to each other in a head-to-tail orientation, with the FIGF polyadenylation signal about 12 kb from the PIGA transcriptional start site.

Amino Acid Sequence↗
PubMed1998

A human homologue of the Drosophila melanogaster diaphanous gene is disrupted in a patient with premature ovarian failure: evidence for conserved function in oogenesis and implications for human sterility.

Premature ovarian failure (POF) is a defect of ovarian development and is characterized by primary or secondary amenorrhea, with elevated levels of serum gonadotropins, or by early menopause. The disorder has been attributed to various causes, including rearrangements of a large "critical region" in the long arm of the X chromosome. Here we report identification, in a family with POF, of a gene that is disrupted by a breakpoint. The gene is the human homologue of the Drosophila melanogaster diaphanous gene; mutated alleles of this gene affect spermatogenesis or oogenesis and lead to sterility. The protein (DIA) encoded by the human gene (DIA) is the first human member of the growing FH1/FH2 protein family. Members of this protein family affect cytokinesis and other actin-mediated morphogenetic processes that are required in early steps of development. We propose that the human DIA gene is one of the genes responsible for POF and that it affects the cell divisions that lead to ovarian follicle formation.

Amino Acid Sequence↗
PubMed1998

The mouse Mid1 gene: implications for the pathogenesis of Opitz syndrome and the evolution of the mammalian pseudoautosomal region.

We have recently reported isolation of the gene responsible for X-linked Opitz G/BBB syndrome, a defect of midline development. MID1 is located on the distal short arm of the human X chromosome (Xp22. 3) and encodes a novel member of the B box family of zinc finger proteins. We have now cloned the murine homolog of MID1 and performed preliminary expression studies during development. Mid1 expression in undifferentiated cells in the central nervous, gastrointestinal and urogenital systems suggests that abnormal cell proliferation may underlie the defect in midline development characteristic of Opitz syndrome. We have also found that Mid1 is located within the mouse pseudoautosomal region (PAR) in Mus musculus , while it seems to be X-specific in Mus spretus. Therefore, Mid1 is likely to be a recent acquisition of the M. musculus PAR. Genetic and FISH analyses also demonstrated a high frequency of unequal crossovers in the murine PAR, creating spontaneous deletion/duplication events involving Mid1. These data provide evidence for the first time that genetic instability of the PAR may affect functionally important genes. In addition, we show that MID1 is the first example of a gene subject to X-inactivation in man while escaping it in mouse. These data contribute to a better understanding of the molecular content and evolution of the rodent PAR.

Abnormalities, Multiple↗
PubMed1998

Chromosome 20 ring: a chromosomal disorder associated with a particular electroclinical pattern.

PURPOSE: The chromosome 20 ring [r(20)] is a rare chromosomal disorder without clear phenotypical markers. We describe the electroclinical pattern in a group of patients with r(20). METHODS: We observed 3 patients (a boy, patient 1; his mother, patient 2; and an unrelated man, patient 3), performing prolonged video-EEG and cytogenetic studies and fluorescent in situ hybridization (FISH) with chromosome-specific telomeric probes. RESULTS: All 3 patients had a very similar abnormal electroclinical pattern characterized by long bursts or trains of rhythmic theta waves, which were sharply contoured or had a notched appearance (with no detectable clinical correlate), and generalized spike waves (SW) associated with seizures of probable frontotemporal origin (SFT). In all 3 patients, the cytogenetic analysis of T lymphocytes showed mosaicism with a normal cell line and a second cell line with a chromosome 20, although the latter was little represented in patients 2 and 3. A few cells with a single chromosome 20 were also found. The same cytogenetic findings were confirmed in the lymphoblastoid cell line of patient 1 and in the fibroblasts of patient 3. FISH with chromosome-specific telomeric probes and TTAGGG sequences demonstrated the integrity of the ring chromosomes. CONCLUSIONS: The clinical picture of these patients appears to be related to the instability of the r(20)-generating cells monosomic for chromosome 20 and is thus haploinsufficient for a gene. In these patients, the electroclinical pattern of theta waves (probably unrelated to epilepsy) and the SW and SFT, even with mild mental retardation (MR) or no MR and without dysmorphic features, suggest that the r(20) syndrome may be present.

Adolescent↗
PubMed1998

Agenesis of the corpus callosum with Probst bundles owing to haploinsufficiency for a gene in an 8 cM region of 6q25.

Agenesis of the corpus callosum (ACC) is a relatively common brain abnormality resulting from developmental defects either limited to the structures leading to the proper formation of the corpus callosum or involving the embryo forebrain more generally. ACC is genetically heterogeneous with autosomal dominant, autosomal recessive, and X linked inheritance and has also been reported in subjects with aneuploidies involving several chromosomes. Among them, distal 6q deletions have been consistently reported in association with ACC, suggesting that there is a gene in the deleted region whose haploinsufficiency impairs normal corpus callosum development. We have studied a child with ACC with Probst bundles and a deletion at 6q25 of about 8 cM, from D6S1496 to D6S437. Probst bundles are the axons that should have formed the corpus callosum but, unable to cross the midline owing to absence of the massa commissuralis, they run longitudinally along the medial walls of the lateral ventricles from the frontal to the occipital lobes. Thus, their presence suggests that a gene located in the 6q deleted region is specifically involved in the formation of the massa commissuralis and that its haploinsufficiency leads to primary ACC.

Agenesis of Corpus Callosum↗