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Biomedical subjects

G Camerino

Publications and source records attributed to G Camerino.

At least 37 records · Page 2Linked to original sources
PubMed1992

Identification of novel RFLPs in the vicinity of CpG islands in Xq28: application to the analysis of the pattern of X chromosome inactivation.

Probes for CpG islands were cloned from the distal long arm of the human X chromosome; three of them were found to be polymorphic. A HindIII RFLP was identified by the probe 2-25 (DXS606), and it was mapped to the Xq27-Xq28 boundary. Probes 2-19 (DXS605) and 2-55 (DXS707), which identify EcoRI and MspI polymorphisms, respectively, have been mapped to the distal part of Xq28, in the G6PD-RCP/GCP gene region. Probe 2-19 has been further localized about 16 kb from the 3' end of the G6PD gene. The new RFLPs may be useful for the precise mapping of the many disease genes localized in this part of the human X chromosome. Probe 2-19 is highly informative, and it has been studied in greater detail. Using the methylation-sensitive rare-cutter enzyme EagI in conjunction with the polymorphic EcoRI site, we were able to demonstrate that the RFLP may be used both to study randomness of X chromosome inactivation and for carrier detection in X-linked syndromes where nonrandom X inactivation occurs. It is conceivable that the combined use of 2-19 and of the probes described so far (pSPT-PGK and M27 beta) will make analysis of X inactivation feasible in virtually every female.

Alleles↗
PubMed1991

A gene deleted in Kallmann's syndrome shares homology with neural cell adhesion and axonal path-finding molecules.

Kallmann's syndrome (clinically characterized by hypogonadotropic hypogonadism and inability to smell) is caused by a defect in the migration of olfactory neurons, and neurons producing hypothalamic gonadotropin-releasing hormone. A gene has now been isolated from the critical region on Xp22.3 to which the syndrome locus has been assigned: this gene escapes X inactivation, has a homologue on the Y chromosome, and shows an unusual pattern of conservation across species. The predicted protein has significant similarities with proteins involved in neural cell adhesion and axonal pathfinding, as well as with protein kinases and phosphatases, which suggests that this gene could have a specific role in neuronal migration.

Base Sequence↗
PubMed1991

Mapping the gene encoding the human erythroid transcriptional factor NFE1-GF1 to Xp11.23.

The X-linked NFE1 gene encodes an erythroid factor involved in globin gene transcription. Using a human cDNA clone encoding this factor, we show, by in situ hybridization and by analysis of human-rodent hybrid cell lines, that this gene is located in Xp11.23. In the absence of polymorphisms in the NFE1 gene, these results allow the study of the possible relationships between NFE1 mutations and X-linked hereditary persistence of fetal hemoglobin by linkage analysis with RFLP markers of the region. A female patient, hemizygous for the NFE1 locus, shows essentially normal hematological parameters.

Cell Line↗
PubMed1991

Analysis of X-chromosome inactivation in X-linked immunodeficiency with hyper-IgM (HIGM1): evidence for involvement of different hematopoietic cell lineages.

The pattern of X-chromosome inactivation was analyzed, by means of two different DNA probes (pSPT-PGK and M27 beta), in several cell lineages derived from females belonging to a pedigree with X-linked immunodeficiency with hyper-IgM (HIGM1). Non-random X-chromosome inactivation was demonstrated in T cells, B cells, and neutrophils, but not in fibroblasts, of obligate carriers, suggesting that different hematopoietic cell lineages are primarily involved in HIGM1. Preferential inactivation of the paternally derived X-chromosome was demonstrated by analysis of segregation of the alleles defined by the pSPT-PGK and M27 beta probes. The possibility that the HIGM1 mutation may confer a proliferative and/or differential advantage to hematopoietic precursors carrying the mutated allele on the active X-chromosome is discussed.

B-Lymphocytes↗
PubMed1991

X-linked Charcot-Marie-Tooth disease. A linkage study in a large family by using 12 probes of the pericentromeric region.

Linkage analysis was performed on 41 subjects belonging to a large family with a recurrence of X-linked Charcot-Marie-Tooth disease (CMTX), by using 12 restriction fragment length polymorphism markers mapping in p11-q13. The results are in agreement with previous linkage data. Three new markers that are potentially useful for genetic analysis of CMTX families are described. A more precise estimate of the localization of the disease locus was attempted by multipoint linkage analysis.

Blotting, Southern↗
PubMed1991

A deletion map of the human Yq11 region: implications for the evolution of the Y chromosome and tentative mapping of a locus involved in spermatogenesis.

A deletion map of Yq11 has been constructed by analyzing 23 individuals bearing structural abnormalities (isochromosomes, terminal deletions and X;Y, Y;X, or A;Y translocations) in the long arm of the Y chromosome. Twenty-two Yq-specific loci were detected using 14 DNA probes, ordered in 11 deletion intervals, and correlated with the cytogenetic map of the chromosome. The breakpoints of seven translocations involving Xp22 and Yq11 were mapped. The results obtained from at least five translocations suggest that these abnormal chromosomes may result from aberrant interchanges between X-Y homologous regions. The use of probes detecting Yq11 and Xp22.3 homologous sequences allowed us to compare the order of loci within these two chromosomal regions. The data suggest that at least three physically and temporary distinct rearrangements (pericentric inversion of pseudoautosomal sequences and/or X-Y transpositions and duplications) have occurred during evolution and account for the present organization of this region of the human Y chromosome. The correlation between the patient' phenotypes and the extent of their Yq11 deletions permits the tentative assignment of a locus involved in human spermatogenesis to a specific interval within Yq11.23.

Adolescent↗
PubMed1991

Deletions within the pseudoautosomal region help map three new markers and indicate a possible role of this region in linear growth.

Short stature is consistently found in individuals with terminal deletions of Xp. In order to refine the localization of a putative locus affecting height, we analyzed two patients with a partial monosomy of the pseudoautosomal region at the molecular level. Eight pseudoautosomal probes were used for the genetic deletion analysis through dose evaluation. Three of them represent new markers (DXS415, DXS419, and DXS406) which were positioned on the pseudoautosomal map by pulsed field gel electrophoresis. Our data suggest that a locus affecting height maps in a region of about 1.5 Mbp, distal to the DXS406 locus and proximal to the DXS415 locus, a region which includes two CpG islands, and rule out an involvement of very distal sequences at the X/Y telomeres.

Adult↗
PubMed1990

Two families of low-copy-number repeats are interspersed on Xp22.3: implications for the high frequency of deletions in this region.

The locations of two families of low-copy-number repeats (CRI-S232 and G1.3) in the physical and genetic maps of the distal short arm of the human X chromosome (Xp22.3) have been determined. Single-copy fragments flanking several repeat elements from each family have been cloned and assigned to specific intervals on a deletion map of Xp22.3. Physical distances between these loci and previously isolated Xp22.3 markers have been determined by pulsed-field gel electrophoresis (PFGE). The positions of some of these markers on the genetic map of the region have been established by segregation analysis in CEPH families. Four members of the CRI-S232 family have been localized within 3 Mb on Xp22.3, interspersed with two members of the G1.3 family. Both deletion and PFGE mapping data suggest that a CpG island localized in a specific position on the map might be associated with the Kallmann syndrome gene. Unlike the previously reported data on hyperpolymorphic minisatellite sequences, no increase in the recombination rate was detected around the CRI-S233 repeats. The presence of several repeat elements in a region with a very high frequency of deletions, such as Xp22.3, is highly suggestive of the occurrence of unequal crossovers between the various elements, leading to deletion events.

Chromosome Deletion↗
PubMed1989

Cytogenetic and molecular analysis of an unbalanced translocation (X;7) (q28;p15) in a dysmorphic girl.

A severely retarded and dysmorphic girl, carrying an unbalanced X/7 translocation with breakpoints at Xq28 and 7p14, was analyzed by cytogenetic, biochemical and molecular techniques. The X/7 translocated chromosome was found to replicate consistently late in the 105 metaphases analyzed. In 83 of these cells, late replication was limited to the X portion of the abnormal chromosome, whereas in 22 cells incomplete spreading into the autosomal fragment was observed. Southern blot and in situ hybridization experiments with probe G80 (locus D7S373) (previously localized to 7p13-15) and G98 (localized to 7p14-15) assigns the former to 7p15 and the latter to 7p14, thus suggesting the order 7ter-G80-G98-cen. The activity of the enzyme phosphoserine phosphatase localized to 7pter-p14 was increased. Southern blotting experiments with 19 probes spanning the entire X chromosome demonstrated that the translocated chromosome had lost a portion of Xq28 (locus DXS51) but still retained part of Xq27 (F9 locus). The results confirm that the proband is trisomic for the region 7p15-pter and monosomic for the region Xq28-qter. Comparing her phenotype with those of other cases of partial trisomy or monosomy 7p, we confirm that band 7q21 is probably involved in skull development.

Abnormalities, Multiple↗
PubMed1988

A highly conserved sequence on the short arm of chromosome 7 detects multiple polymorphisms.

We have isolated a human DNA fragment (laboratory acronym G98) that detects related sequences in mammals, chicken and Drosophila DNAs. This sequence has been mapped to human chromosome 7 p14-p15 by in situ hybridization. Probe G98 recognizes an insertion-deletion type polymorphism, with allelic frequencies of about 0.5, which can be detected with at least six different restriction enzymes. A second polymorphism, which can be detected in human DNA digested with TaqI, is in non-complete linkage disequilibrium with the first polymorphism. About 70% of the individuals analysed have been found to be heterozygous at this locus.

Animals↗
PubMed1988

Characterization of a partial deletion of the factor VIII gene in a haemophiliac with inhibitor.

Genomic DNA from 49 Italian patients affected with severe haemophilia A was analysed by Southern blotting technique using a cDNA probe corresponding to exons 14-26 of coagulation factor VIII. No TaqI site mutation was observed in this sample. A partial deletion, eliminating exons 15-18 and spanning about 13kb, was identified and characterized in one patient with anti-factor VIII antibodies.

Antibodies↗
PubMed1988

Isolation and characterization of a family of sequences dispersed on the human X chromosome.

During a systematic search for X-specific sequences we isolated a DNA fragment (called G1.3) that hybridizes to six further homologous X-specific genomic fragments that map to at least four different regions of the human X chromosome. Genomic segments of 11-30 kb (called G1.3 a, b, c, d, and e or DNF22S1 to DNF22S5) have been subsequently cloned for five of the seven repetitions and characterized by restriction mapping. Single-copy sequences have been used to analyze homology between cloned repetitions, to confirm X specificity, and to regionally localize the repetitions. Sequence homology between members of this family seems to be very high (80-90%) and to extend over at least 5 to 12 kb. In situ hybridization and Southern blotting experiments with a panel of human-rodent hybrid cell lines demonstrated that four of the cloned sequences map to three different regions within Xp21.2-pter and the fifth one (G1.3c) maps to Xq28. The family is present with the same complexity and X specificity in macaques (20-30 x 10(6) years divergence with man), whereas no related sequences were detected in the mouse. To our knowledge small families of dispersed chromosome-specific sequences have been described only for the human Y chromosome. The possible functional or evolutionary significance of this family is discussed.

Animals↗
PubMed1987

Combined use of DNA probes in first-trimester prenatal diagnosis of hemophilia A.

First-trimester prenatal diagnoses of hemophilia A were heretofore obtained by using either intragenic factor VIII markers or linked extragenic polymorphic markers. Postulating that the combined use of all the available intragenic and extragenic markers can render such diagnoses more frequently feasible and more reliable, we carried out ten first-trimester prenatal diagnoses in male fetuses at risk for hemophilia A by DNA analysis of chorionic villus employing in combination the intragenic Bcl I polymorphism and the St 14 (DXS 52) or DX 13 (DXS 15) extragenic probes. A diagnosis of hemophilia was obtained in three fetuses, with a diagnosis of normal fetus obtained in the remaining seven. Seven diagnoses are confirmed by factor VIII assays carried out at the time of abortion, in the mid-trimester or at birth. A factor VIII probe recognizing Bcl I polymorphism was useful in 4 of 6 diagnoses; St 14, in 5 of 6; and DX 13 in 3 of 5. In two cases, St 14 was the only useful probe for diagnosis. Even though no recombination between extragenic probes and factor VIII gene was detected in this study, when only extragenic markers were informative we advised diagnostic confirmation on fetal plasma obtained by fetoscopy. Hence, first-trimester prenatal diagnosis of hemophilia A is feasible for the great majority of fetuses at risk through combined use of all the available intragenic and extragenic probes, providing key family members are available.

Adult↗
PubMed1987

Multipoint genetic mapping of the Xq26-q28 region in families with fragile X mental retardation and in normal families reveals tight linkage of markers in q26-q27.

The q26-q28 region of the human X chromosome contains several important disease loci, including the locus for the fragile X mental retardation syndrome. We have characterized new polymorphic DNA markers useful for the genetic mapping of this region. They include a new Bell restriction fragment length polymorphism (RFLP) detected by the probe St14-1 (DXS52) and which may therefore be of diagnostic use in hemophilia A families. A linkage analysis was performed in fragile X families and in large normal families from the Centre d'Etude du Polymorphisme Humain (CEPH) by using seven polymorphic loci located in Xq26-q28. This multipoint linkage study allowed us to establish the order centromere-DXS100-DXS86-DXS144-DXS51-F9-FRAX+ ++-(DXS52-DXS15). Together with other studies, our results define a cluster of nine loci that are located in Xq26-q27 and map within a 10 to 15 centimorgan region. This contrasts with the paucity of markers (other than the fragile X locus) between the F9 gene in q27 and the G6PD cluster in q28, which are separated by about 30% recombination.

Chromosome Mapping↗