1
|
The role of personality variables in predicting attitudes toward people with intellectual disability: An Australian perspective. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2015; 59:741-745. [PMID: 25559160 DOI: 10.1111/jir.12180] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/19/2014] [Indexed: 06/04/2023]
Abstract
BACKGROUND Personality dimensions such as openness and agreeableness have been found to be associated with prejudice levels towards several minority groups. Yet these variables have been mostly ignored by existing research into attitudes towards people with intellectual disability (PWID), which has primarily focused on contact and demographic variables. The current study investigated the relationship between personality dimensions and attitudes toward PWID. METHODS An online survey was completed by 466 adult participants recruited through a variety of sources. The survey consisted of a well-validated attitude survey, the Big Five inventory, contact related and demographic questions. RESULTS The hypothesis that higher levels of the personality dimensions openness and agreeableness would be significantly associated with positive attitudes towards PWID was supported. However the effect was relatively weak and the strongest predicting factor of positive attitudes was increased quality of contact with PWID. More positive attitudes were also associated with females, more highly educated and younger participants. CONCLUSIONS Results provide support for an integrated (including person and situational factors) theoretical approach to attitudes research in this field. Practically, results support programmes that stimulate and promote quality interactions between PWID and the wider community.
Collapse
|
2
|
De novo donor-specific HLA antibodies: biomarkers of pancreas transplant failure. Am J Transplant 2014; 14:1664-71. [PMID: 24866735 DOI: 10.1111/ajt.12750] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 03/18/2014] [Accepted: 03/19/2014] [Indexed: 01/25/2023]
Abstract
This study assesses the role of posttransplant HLA antibody monitoring in the surveillance of pancreas transplant recipients. Four hundred thirty-three pancreas transplants were performed at the Oxford Transplant Centre 2006-2011 (317 simultaneous pancreas kidney [SPK] and 116 isolated pancreas [IP]). HLA antibody monitoring was performed at 0, 6 and 12 months and annually and during clinical events. There was no association between pancreas graft failure and recipient or donor characteristics. Posttransplant antibody status, available for 354 (81.8%) of recipients, demonstrated that 141 (39.8%) developed de novo HLA antibodies, of which 52 (36.9%) were de novo donor-specific HLA antibodies (DSA) (34 SPK, 18 IP). The development of antibodies to donor HLA, but not to nondonor HLA, was significantly associated with poorer graft outcomes, with 1- and 3-year graft survival inferior in SPK recipients (85.2% vs. 93.5%; 71.8% vs. 90.3%, respectively; log-rank p = 0.002), and particularly in IP recipients (50.0% vs. 82.9%; 16.7 vs. 79.4%, respectively; log-rank p = 0.001). In a multivariate analysis, development of de novo DSA emerged as a strong independent predictor of pancreas graft failure (hazard ratio 4.66, p < 0.001). This is the largest study to examine de novo HLA antibodies following pancreas transplantation and clearly defines a high-risk group in need of specific intervention.
Collapse
|
3
|
Ageing of the baby boomer generation: how demographic change will impact on city and rural GP and nursing workforce. Rural Remote Health 2006; 6:604. [PMID: 17061915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
INTRODUCTION OBJECTIVE To compare the impact of ageing on the GP and nursing rural and city workforce. METHOD Cohort analysis of Australian Bureau of Statistics census data. The data was used to examine the age distribution of the city and rural GP and nursing workforce; patterns of attrition for those 50 years and over; and the impact of changes in working hours. RESULTS The rural GP and nursing workforce is significantly older than their city counterparts (p<0.001) with the 'baby boomer' generation making up 52% of city GPs but 59% of rural GPs in 2001. While a large proportion of city and rural GPs continued to work past the age of 65 years, rural GPs left the workforce at a significantly younger age than city doctors (p<0.001). Rural nurses are older than their city peers (p<0.001) but retire at an older age than city nurses (p<0.001). In 1986, a significantly higher proportion of rural GPs in all age cohorts worked more than 41 hours per week compared with their city counterparts (p<0.001). By 2001, rural 'generation X' GPs were no more likely to work long hours than those in the city (p<0.001). However, significantly more rural than city 'baby boomers' continued to work long hours. CONCLUSIONS Rural GPs are retiring faster than city GPs and strategies to attract rural GPs and nurses will be critical to ensure adequate rural health care and that current rural workforce shortage do not worsen.
Collapse
|
4
|
Abstract
The meiotic mutant c(3)G (crossover suppressor on 3 of Gowen) abolishes both synaptonemal complex (SC) formation and meiotic recombination, whereas mutations in the mei-W68 and mei-P22 genes prevent recombination but allow normal SC to form. These data, as well as a century of cytogenetic studies, support the argument that meiotic recombination between homologous chromosomes in Drosophila females requires synapsis and SC formation. We have cloned the c(3)G gene and shown that it encodes a protein that is structurally similar to SC proteins from yeast and mammals. Immunolocalization of the C(3)G protein, as well as the analysis of a C(3)G-eGFP expression construct, reveals that C(3)G is present in a thread-like pattern along the lengths of chromosomes in meiotic prophase, consistent with a role as an SC protein present on meiotic bivalents. The availability of a marker for SC in Drosophila allowed the investigation of the extent of synapsis in exchange-defective mutants. These studies indicate that SC formation is impaired in certain meiotic mutants and that the synaptic defect correlates with the exchange defects. Moreover, the observation of interference among the residual exchanges in these mutant oocytes implies that complete SC formation is not required for crossover interference in Drosophila.
Collapse
|
5
|
Identification and characterization of satellite III subfamilies to the acrocentric chromosomes. Chromosome Res 2001; 9:223-33. [PMID: 11330397 DOI: 10.1023/a:1016648404388] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The centromeres and the short arms of the five pairs of acrocentric chromosomes in humans are composed of tandemly ordered repetitive DNA. Previous studies have suggested that the exchanges between acrocentric chromosomes have resulted in concerted evolution of different DNA sequences in their short arms. The acrocentric chromosomes are clinically relevant since they are involved in Robertsonian translocation formation and non-disjunction resulting in aneuploidy. Here we have identified seven new satellite III repetitive DNA subfamilies, determined their nucleotide sequences and established their chromosomal distributions on the short arms of the acrocentric chromosomes. Knowledge of these related sequences may help to elucidate the molecular basis of Robertsonian translocation formation.
Collapse
|
6
|
Abstract
Robertsonian translocations (ROBs) are the most common rearrangements in humans, contributing significantly to genetic imbalance, fetal wastage, mental retardation and birth defects. Rob(14q21q) and rob(13q14q), which are formed predominantly during female meiosis, comprise the majority (approximately 85%) of all ROBs. Previous studies have shown that the breakpoints are consistently located within specific regions of the proximal short arms of chromosomes 13, 14, and 21. The high prevalence of these translocations, the consistent breakpoints found, and the fact that roughly 50% of cases occur sporadically suggest that the sequences at or near the breakpoints confer susceptibility to chromosome rearrangement and that the rearrangements occur through a specific mechanism. To investigate this hypothesis, we developed hamster-human somatic cell hybrids derived from de novo rob(14q21q) patients that contained the translocated chromosome segregated from the other acrocentric chromosomes. We determined the physical order of five satellite III subfamilies on 14p, and investigated their involvement in formation of these de novo translocations.
Collapse
|
7
|
Catarrhine phylogeny: noncoding DNA evidence for a diphyletic origin of the mangabeys and for a human-chimpanzee clade. Mol Phylogenet Evol 2001; 18:14-25. [PMID: 11161738 DOI: 10.1006/mpev.2000.0895] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Maximum-parsimony and maximum-likelihood analyses of two of the serum albumin gene's intron sequences from 24 catarrhines (17 cercopithecid and 7 hominid) and 3 platyrrhines (an outgroup to the catarrhines) yielded results on catarrhine phylogeny that are congruent with those obtained with noncoding sequences of the gamma(1)-gamma(2) globin gene genomic region, using only those flanking and intergenic gamma sequences that in their history were not involved in gene conversion. A data set that combined in a tandem alignment these two sets of noncoding DNA orthologues from the two unlinked nuclear genomic loci yielded the following confirmatory results both on the course of cladistic branchings (the divisions in a cladistic classification of higher ranking taxa into subordinate taxa) and on the ages of the taxa (each taxon representing a clade). The cercopithecid branch of catarrhines, at approximately 14 Ma (mega annum) divided into Colobini (the leaf-eating Old World monkeys) and Cercopithecini (the cheek-pouched Old World monkeys). At approximately 10-9 Ma, Colobini divided into an African clade, Colobina, and an Asian clade, Presbytina; similarly at this time level, Cercopithecini divided into Cercopithecina (the guenons, patas, and green monkeys) and Papionina. At approximately 7 Ma, Papionina divided into Macaca, Cercocebus, and Papio. At approximately 5 Ma, Cercocebus divided subgenerically into C. (Cercocebus) for terrestrial mangabeys and C. (Mandrillus) for drills and mandrills, while at approximately 4 Ma Papio divided subgenerically into P. (Locophocebus) for arboreal mangabeys, P. (Theropithecus) for gelada baboons, and P. (Papio) for hamadryas baboons. In turn, the hominid branch of catarrhines at approximately 18 Ma divided into Hylobatini (gibbons and siamangs) and Hominini; at approximately 14 Ma, Hominini divided into Pongina (orangutans) and Hominina; at approximately 7 Ma, Hominina divided into Gorilla and Homo; and at approximately 6-5 Ma, Homo divided subgenerically into H. (Homo) for humans and H. (Pan) for common and bonobo chimpanzees. Rates of noncoding DNA evolution were assessed using a data set of noncoding gamma sequence orthologues that represented 18 catarrhines, 16 platyrrhines, 3 non-anthropoid primates (2 tarsiers and 1 strepsirhine), and rabbit (as outgroup to the primates). Results obtained with this data set revealed a faster rate of nucleotide substitutions in the early primate lineage to the anthropoid (platyrrhine/catarrhine) ancestor than from that ancestor to the present. Rates were slower in catarrhines than in platyrrhines, slower in the cheek-pouched than in the leaf-eating cercopithecids, and slower yet in the hominids. On relating these results to data on brain sizes and life spans, it was suggested that life-history strategies that favor intelligence and longer life spans also select for decreases in de novo mutation rates.
Collapse
|
8
|
Genetic studies of mei-P26 reveal a link between the processes that control germ cell proliferation in both sexes and those that control meiotic exchange in Drosophila. Genetics 2000; 155:1757-72. [PMID: 10924472 PMCID: PMC1461182 DOI: 10.1093/genetics/155.4.1757] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We present the cloning and characterization of mei-P26, a novel P-element-induced exchange-defective female meiotic mutant in Drosophila melanogaster. Meiotic exchange in females homozygous for mei-P26(1) is reduced in a polar fashion, such that distal chromosomal regions are the most severely affected. Additional alleles generated by duplication of the P element reveal that mei-P26 is also necessary for germline differentiation in both females and males. To further assess the role of mei-P26 in germline differentiation, we tested double mutant combinations of mei-P26 and bag-of-marbles (bam), a gene necessary for the control of germline differentiation and proliferation in both sexes. A null mutation at the bam locus was found to act as a dominant enhancer of mei-P26 in both males and females. Interestingly, meiotic exchange in mei-P26(1); bam(Delta)(86)/+ females is also severely decreased in comparison to mei-P26(1) homozygotes, indicating that bam affects the meiotic phenotype as well. These data suggest that the pathways controlling germline differentiation and meiotic exchange are related and that factors involved in the mitotic divisions of the germline may regulate meiotic recombination.
Collapse
|
9
|
Molecular phylogeny of Old World monkeys (Cercopithecidae) as inferred from gamma-globin DNA sequences. Mol Phylogenet Evol 1999; 13:348-59. [PMID: 10603263 DOI: 10.1006/mpev.1999.0653] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
DNA sequence data of the nuclear-encoded gamma1-gamma2-globin duplication region were used to examine the phylogenetic relationships of 16 cercopithecid (Old World monkey) species representing 12 extant genera. Morphology- and molecular-based hypotheses of Old World monkey branching patterns are generally congruent, except for generic relationships within the subtribe Papionina. The cercopithecids divide into colobines (leaf-eating monkeys) and cercopithecines (cheek-pouched monkeys). The colobines examined by the DNA data divide into an Asian clade (Nasalis, proboscis monkeys; Trachypithecus, langurs) and an African clade (Colobus, colobus monkeys). The cercopithecines divide into tribes Cercopithecini (Erythrocebus, patas monkey; Chlorocebus, green monkeys; Cercopithecus, guenons) and Papionini. Papionins divide into subtribes Macacina (Macaca, macaques) and Papionina (Papio, hamadryas baboons; Mandrillus, drills and mandrills; Theropithecus, gelada baboons; Lophocebus, arboreal mangabeys; Cercocebus, terrestrial mangabeys). In a morphologically based classification, Mandrillus is a subgenus of Papio, whereas Lophocebus is a subgenus of Cercocebus. In contrast, the molecular evidence treats Mandrillus as a subgenus of Cercocebus, and treats both Theropithecus and Lophocebus as subgenera of Papio. Local molecular clock divergence time estimates were used as a yardstick in a "rank equals age" system to propose a reduction in taxonomic rank for most clades within Cercopithecidae.
Collapse
|
10
|
The place of Callimico goeldii in the Callitrichine phylogenetic tree: evidence from von Willebrand factor gene intron II sequences. Mol Phylogenet Evol 1999; 13:392-404. [PMID: 10603266 DOI: 10.1006/mpev.1999.0658] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sequences of a 0.9-kb DNA segment spanning intron 11 of the von Willebrand Factor gene (vWF) were determined for 21 individuals of 19 primate species. The results of maximum parsimony and maximum likelihood analyses of these vWF sequences are congruent with previous molecular findings from other nonlinked nuclear genomic loci which divide the platyrrhine superfamily Ceboidea into three monophyletic families: Cebidae, Atelidae, and Pitheciidae. The vWF results strongly support the taxon Callitrichinae as a monophyletic subfamily within Cebidae. The four extant callitrichine genera constitute tribe Callitrichini, and the basal branchings within this tribe first separate out Saguinus (tamarins), next Leontopithecus (lion tamarins), and last the sister genera Callimico (Goeldi's monkeys) and Callithrix (marmosets). Callithrix divides into three subclades, with pygmy marmosets (C. pygmaea) as sister of the C. argentata species group and with the C. jacchus species group as their sister. Fossil and DNA evidence place the emergence of the callitrichine clade in the basal cebid radiation at about 20 Ma (million years ago) and the three basal branchings in the callitrichin radiation at about 13 to 11 Ma. In turn, the branchings separating the three subclades of Callithrix are placed at about 5 to 4 Ma.
Collapse
|
11
|
Abstract
The segregation of homologous chromosomes from one another is the essence of meiosis. In many organisms, accurate segregation is ensured by the formation of chiasmata resulting from crossing over. Drosophila melanogaster females use this type of recombination-based system, but they also have mechanisms for segregating achiasmate chromosomes with high fidelity. We describe a P-element mutagenesis and screen in a sensitized genetic background to detect mutations that impair meiotic chromosome pairing, recombination, or segregation. Our screen identified two new recombination-deficient mutations: mei-P22, which fully eliminates meiotic recombination, and mei-P26, which decreases meiotic exchange by 70% in a polar fashion. We also recovered an unusual allele of the ncd gene, whose wild-type product is required for proper structure and function of the meiotic spindle. However, the screen yielded primarily mutants specifically defective in the segregation of achiasmate chromosomes. Although most of these are alleles of previously undescribed genes, five were in the known genes alphaTubulin67C, CycE, push, and Trl. The five mutations in known genes produce novel phenotypes for those genes.
Collapse
|
12
|
Molecular analysis of mosaicism for two different de novo acrocentric rearrangements demonstrates diversity in Robertsonian translocation formation. AMERICAN JOURNAL OF MEDICAL GENETICS 1998; 80:252-9. [PMID: 9843048 DOI: 10.1002/(sici)1096-8628(19981116)80:3<252::aid-ajmg14>3.0.co;2-q] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Robertsonian translocations (ROBs) involving chromosome 21 occur in about 5% of individuals with Down syndrome. ROBs are the most common chromosomal rearrangements in humans and are formed through whole arm exchanges of any two acrocentric chromosomes. The de novo formation of ROBs occurs at exceptionally high rates. The present case concerns a child with mosaic Down syndrome who has two cell lines that contain two different de novo ROBs: 45,XX,rob(14;21)(q10;q10) and 46,XX,rea(21;21)(q10;q10),+21. To elucidate the mechanisms by which the rearrangements formed, somatic cell hybrids were constructed to allow the parental origins of the chromosomes involved in the ROBs to be distinguished. The analysis of the hybrids showed that the rob(14q21q) must have formed postzygotically because it contained a maternal chromosome 14 and a paternal chromosome 21. Furthermore, hybrid analysis of the rea(21q21q) demonstrated two copies of the same chromosome from the mother and thus, by definition, was an isochromosome [i(21q)]. All free-lying chromosomes 21 isolated in hybrids were of maternal origin. These chromosomes may have originated from either of the patient's cell lines. We present four hypotheses for the formation of the two cell lines of this child. This case is part of an ongoing project to determine the mechanism(s) of de novo ROB formation and the results differ from the other de novo rob(14q21q) studied in our laboratory (n = 7) in that all previously studied translocations were maternally derived, leading to the conclusion that most de novo rob(14q21q) occur in oogenesis. The current case illustrates that other mechanisms may contribute to ROB formation.
Collapse
|
13
|
Toward a phylogenetic classification of Primates based on DNA evidence complemented by fossil evidence. Mol Phylogenet Evol 1998; 9:585-98. [PMID: 9668008 DOI: 10.1006/mpev.1998.0495] [Citation(s) in RCA: 553] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A highly resolved primate cladogram based on DNA evidence is congruent with extant and fossil osteological evidence. A provisional primate classification based on this cladogram and the time scale provided by fossils and the model of local molecular clocks has all named taxa represent clades and assigns the same taxonomic rank to those clades of roughly equivalent age. Order Primates divides into Strepsirhini and Haplorhini. Strepsirhines divide into Lemuriformes and Loriformes, whereas haplorhines divide into Tarsiiformes and Anthropoidea. Within Anthropoidea when equivalent ranks are used for divisions within Platyrrhini and Catarrhini, Homininae divides into Hylobatini (common and siamang gibbon) and Hominini, and the latter divides into Pongina for Pongo (orangutans) and Hominina for Gorilla and Homo. Homo itself divides into the subgenera H. (Homo) for humans and H. (Pan) for chimpanzees and bonobos. The differences between this provisional age related phylogenetic classification and current primate taxonomies are discussed.
Collapse
|
14
|
Abstract
BACKGROUND Combination therapy is logical for patients with non-insulin-dependent (type 2) diabetes mellitus, because they often have poor responses to single-drug therapy. We studied the efficacy and physiologic effects of metformin and troglitazone alone and in combination in patients with type 2 diabetes. METHODS We randomly assigned 29 patients to receive either metformin or troglitazone for three months, after which they were given both drugs for another three months. Plasma glucose concentrations during fasting and postprandially and glycosylated hemoglobin values were measured periodically during both treatments. Endogenous glucose production and peripheral glucose disposal were measured at base line and after three and six months. RESULTS During metformin therapy, fasting and postprandial plasma glucose concentrations decreased by 20 percent (58 mg per deciliter [3.2 mmol per liter], P<0.001) and 25 percent (87 mg per deciliter [4.8 mmol per liter], P<0.001), respectively. The corresponding decreases during troglitazone therapy were 20 percent (54 mg per deciliter [2.9 mmol per liter], P=0.01) and 25 percent (83 mg per deciliter [4.6 mmol per liter], P<0.001). Endogenous glucose production decreased during metformin therapy by a mean of 19 percent (P=0.001), whereas it was unchanged by troglitazone therapy (P=0.04 for the comparison between groups). The mean rate of glucose disposal increased by 54 percent during troglitazone therapy (P=0.006) and 13 percent during metformin therapy (P= 0.03 for the comparison within the group and between groups). In combination, metformin and troglitazone further lowered fasting and postprandial plasma glucose concentrations by 18 percent (41 mg per deciliter [2.3 mmol per liter], P=0.001) and 21 percent (54 mg per deciliter [3.0 mmol per liter], P<0.001), respectively, and the mean glycosylated hemoglobin value decreased 1.2 percentage points. CONCLUSIONS Metformin and troglitazone have equal and additive beneficial effects on glycemic control in patients with type 2 diabetes. Metformin acts primarily by decreasing endogenous glucose production, and troglitazone by increasing the rate of peripheral glucose disposal.
Collapse
|
15
|
Chromosome stability is maintained by short intercentromeric distance in functionally dicentric human Robertsonian translocations. Chromosome Res 1998; 6:115-22. [PMID: 9543014 DOI: 10.1023/a:1009286929145] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
While the formation of a dicentric chromosome often leads to chromosome instability, human dicentric Robertsonian translocations usually remain stable. To investigate the basis for this stability, we have examined the centromeres of 15 structurally dicentric rob(13q14q) Robertsonian translocations using immunofluorescence and fluorescence in situ hybridization (FISH). The immunofluorescence detection of centromere protein C (CENP-C) was used as a marker for centromere function as CENP-C seems to play an essential role in kinetochore structure and stability and was previously shown to be absent from inactive centromeres. In all 15 translocation-containing cell lines, CENP-C was confined to only one of the centromeres of the translocation in a fraction of the cells analyzed. This suggests that centromere inactivation commonly occurs on dicentric Robertsonian translocations and may serve as one mechanism allowing for their stability. However, in the majority of the translocations (12 out of 15), a portion of the cells analyzed displayed CENP-C immunofluorescence at both centromeres, suggesting that both centromeres were active and that the translocation was functionally dicentric. The percentage of cells with CENP-C at both centromeres ranged from 2% to 82%. These results support the hypothesis that the close proximity of two functional centromeres on Robertsonian translocations allows them to remain stable.
Collapse
|
16
|
Abstract
We present a prenatal diagnosis of a de novo homologous Robertsonian translocation involving both chromosomes 15. Amniocentesis was performed on a 36-year-old woman at 16.5 weeks of gestation. Chromosome analysis documented a 45,XX,der(15;15) (q10;q10) chromosome pattern. No evidence of a deletion was observed by FISH using a SNRPN DNA probe associated with the Prader-Willi/Angelman syndrome critical region. Molecular studies in the family using six polymorphic markers for chromosome 15 and Southern blot analysis of DNA methylation for the CpG island near the SNRPN gene showed normal biparental inheritance of chromosome 15, excluding uniparental disomy. The patient was counseled that her child would not be able to bear off-spring without clinical assistance. Otherwise the health and intellect of her child were not expected to be affected by the translocation. We consider this to be the first prenatal case identified with a balanced der(15;15)(q10;q10) Robertsonian translocation and a phenotypically normal female outcome. Prenatally identified cases of der(15;15)(q10;q10) warrant further investigation by molecular methodology.
Collapse
|
17
|
|
18
|
Breakpoint diversity illustrates distinct mechanisms for Robertsonian translocation formation. Hum Mol Genet 1996; 5:1279-88. [PMID: 8872467 DOI: 10.1093/hmg/5.9.1279] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Robertsonian translocations are the most common chromosomal rearrangements in humans. The vast majority of the ten possible nonhomologous types of Robertsonian translocations ascertained are rob(13q14q) and rob(14q21q). Recombination between homologous sequences on nonhomologous chromosomes has been proposed as a mechanism leading to the preferential formation of rob(13q14q) and rob(14q21q). However, little evidence exists to indicate whether the remaining less common Robertsonian translocations form through a similar mechanism. To better elucidate the mechanisms involved in Robertsonian translocation formation, we have used fluorescence in situ hybridization to localize the breakpoints in 56 nonhomologous Robertsonian translocations. This study revealed highly variable locations of breakpoints in seven types of the less common Robertsonians, while nearly all rob(13q14q) and rob(14q21q) analyzed displayed breakpoints in the same locations. Therefore, this study provides direct evidence that rob(13q14q) and rob(14q21q) form through a specific mechanism, possibly involving homologous recombination, which is distinct from the mechanism(s) that contributes to the formation of the remaining types of Robertsonian translocations.
Collapse
|
19
|
Further evidence that CENP-C is a necessary component of active centromeres: studies of a dic(X; 15) with simultaneous immunofluorescence and FISH. Hum Mol Genet 1995; 4:289-94. [PMID: 7757082 DOI: 10.1093/hmg/4.2.289] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The stability of certain dicentric chromosomes in humans seems to result from inactivation of one centromere, yielding a functionally monocentric chromosome. Centromere protein C (CENP-C) was previously shown to be present at active centromeres but absent from the inactive centromere of one homologous dicentric rearrangement. We have combined indirect immunofluorescence detection of CENP-C and fluorescence in situ hybridization with chromosome-specific alpha-satellite DNA probes in a simultaneous assay to unequivocally identify the active and inactive centromeres of a dicentric (X;15) translocation. In both fibroblast and lymphoblast cell lines containing the translocation, the X chromosome centromere consistently had a primary constriction and CENP-C immunofluorescence, and is therefore the active centromere. CENP-C was never detected at the chromosome 15 centromere, which appears to be inactive. The inactivation pattern is apparently stable and observed in all cells with the translocation. Immunofluorescence with CREST serum revealed staining at both centromeres of the translocation, and thus was not specific to the active centromere. This study demonstrates the specificity of CENP-C to the active centromere in a non-homologous rearrangement and further establishes CENP-C as an essential component of a functional human centromere.
Collapse
|
20
|
Unbiased analysis of the frequency of beta-thalassemia point mutations in a population of African-American newborns. Arch Pathol Lab Med 1993; 117:1110-4. [PMID: 8239931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To determine frequency of specific beta-thalassemia alleles in the African-American population prospectively, using newborn screening specimens, and to evaluate the need for including these alleles in screening follow-up programs. DESIGN Allele-specific oligonucleotide tests were developed and used to analyze African-American newborn screening specimens for beta-thalassemia point mutations to determine their frequency. Direct sequencing of amplified DNA from the dried blood specimens was used to confirm the presence of point mutations. POPULATION African-American newborns in Texas. RESULTS Allele-specific oligonucleotides identified five newborn specimens carrying beta-thalassemia point mutations among 471 specimens from African-American neonates. Direct sequencing of DNA from the dried blood specimens confirmed that these individuals had a normal and a mutant allele. Five newborn screening specimens in which the results of screening and DNA tests were in disagreement (four with FS by screening and AS by DNA, and one with FC by screening and AC by DNA) were analyzed for these beta-thalassemia point mutations and in each case were found to be S/beta-thalassemia or C/beta-thalassemia compound heterozygotes, respectively. CONCLUSIONS Allele-specific oligonucleotides accurately identified newborn specimens carrying beta-thalassemia point mutations. Direct sequencing from dried blood specimens confirmed these results. The A(-29)G allele frequency was 0.003, and the C(-88)T frequency was 0.002. These alleles also were observed among positive samples in a neonatal hemoglobinopathy screening program. Therefore, any newborn screening program with a molecular genetic follow-up component must include testing for these beta-thalassemia alleles to assure timely and appropriate management for affected infants.
Collapse
|
21
|
|