Search PubMed⌕ Search

Biomedical subjects

L Kearney

Publications and source records attributed to L Kearney.

At least 37 records · Page 2Linked to original sources
PubMed1999

Subtle chromosomal rearrangements in children with unexplained mental retardation.

BACKGROUND: No explanation for moderate to severe mental retardation is apparent in about 40% of cases. Although small chromosomal rearrangements may account for some undiagnosed cases, a lack of genome-wide screening methods has made it impossible to ascertain the frequency of such abnormalities. METHODS: A fluorescence in-situ hybridisation (FISH) test was used to examine the integrity of chromosome ends in 284 children with unexplained moderate to severe retardation, and in 182 children with unexplained mild retardation. 75 normal men were also tested. When a chromosomal rearrangement was found, its size was estimated, and members of the child's family were investigated. FINDINGS: Subtle chromosomal abnormalities occurred with a frequency of 7.4% in the children with moderate to severe mental retardation, and of 0.5% in the children with mild retardation. The abnormalities had an estimated population prevalence of 2.1 per 10,000, and were familial in almost half of cases. INTERPRETATION: Once recognisable syndromes have been excluded, abnormalities that include the ends of chromosomes are the commonest cause of mental retardation in children with undiagnosed moderate to severe mental retardation. Owing to the high prevalence of familial cases, screening for subtle chromosomal rearrangements is warranted in children with unexplained moderate to severe mental retardation.

Adolescent↗
PubMed1999

A new recurrent translocation, t(5;11)(q35;p15.5), associated with del(5q) in childhood acute myeloid leukemia. The UK Cancer Cytogenetics Group (UKCCG)

Partial deletion of the long arm of chromosome 5, del(5q), is the cytogenetic hallmark of the 5q-syndrome, a distinct subtype of myelodysplastic syndrome-refractory anemia (MDS-RA). Deletions of 5q also occur in the full spectrum of other de novo and therapy-related MDS and acute myeloid leukemia (AML) types, most often in association with other chromosome abnormalities. However, the loss of genetic material from 5q is believed to be of primary importance in the pathogenesis of all del(5q) disorders. In the present study, we performed fluorescence in situ hybridization (FISH) studies using a chromosome 5-specific whole chromosome painting probe and a 5q subtelomeric probe to determine the incidence of cryptic translocations. We studied archival fixed chromosome suspensions from 36 patients with myeloid disorders (predominantly MDS and AML) and del(5q) as the sole abnormality. In 3 AML patients studied, this identified a translocation of 5q subtelomeric sequences from the del(5q) to the short arm of an apparently normal chromosome 11. FISH with chromosome 11-specific subtelomeric probes confirmed the presence of 11p on the shortened 5q. Further FISH mapping confirmed that the 5q and 11p translocation breakpoints were the same in all 3 cases, between the nucleophosmin (NPM1) and fms-related tyrosine kinase 4 (FLT4) genes on 5q35 and the Harvey ras-1-related gene complex (HRC) and the radixin pseudogene (RDPX1) on 11p15.5. Importantly, all 3 patients with the cryptic t(5;11) were children: a total of 3 of 4 AML children studied. Two were classified as AML-M2 and the third was classified as M4. All 3 responded poorly to treatment and had short survival times, ranging from 10 to 18 months. Although del(5q) is rare in childhood AML, this study indicates that, within this subgroup, the incidence of cryptic t(5;11) may be high. It is significant that none of the 24 MDS patients studied, including 11 confirmed as having 5q-syndrome, had the translocation. Therefore, this appears to be a new nonrandom chromosomal translocation, specifically associated with childhood AML with a differentiated blast cell phenotype and the presence of a del(5q).

Adult↗
PubMed1999

Delineation of multiple deleted regions in 7q in myeloid disorders.

Loss of chromosome material due to deletions of the long arm of chromosome 7, del(7q), is a consistent finding in all types of myeloid disorders, invariably associated with a poor prognosis. Two different segments, 7q22 and 7q32-q33, have been implicated as critical regions of gene loss associated with these disorders. In the present study, we used fluorescence in situ hybridization (FISH) to characterize the 7q22 breakpoint of an apparently balanced t(7;7)(p13;q22) in an acute myeloid leukemia patient. FISH analysis on bone marrow metaphases from this patient revealed that the sequence corresponding to a series of three ordered cosmids from 7q22 was deleted from one of the der(7) chromosomes. These cosmids contain the human homologue of the Drosophila homeobox gene cut (CUTL1) and span a region of approximately 150 kb. Although the proximal boundary of the deleted segment could not be exactly defined, we estimate the size of this deletion to be approximately 500 kb. Subsequently, we carried out FISH studies using the CUTL1 cosmids on a further 16 patients with deletions of 7q and myeloid disorders. The sequence corresponding to at least two of the cosmids was deleted from the del(7q) in 11 out of 14 cases with a proximal breakpoint within 7q22. Further detailed FISH mapping in this series of 17 patients has identified two other nonoverlapping commonly deleted segments at 7q31-q32 and 7q33, respectively. These data confirm and refine other studies, implying that several different genes on 7q may be involved in the pathogenesis of myeloid diseases. Genes Chromosomes Cancer 25:384-392, 1999.

Adult↗
PubMed1999

Characterization of the human myeloid leukemia-derived cell line GF-D8 by multiplex fluorescence in situ hybridization, subtelomeric probes, and comparative genomic hybridization.

The human myeloid leukemia cell line GF-D8 was established from the peripheral blood blasts of a patient with acute myeloid leukemia FAB subtype MI (AML-MI). The karyotype, which has not changed significantly over several years of culture, was described initially as 44,XY,-5,del(7q),inv(7q),add(8q),add(11q),del(12p),-15,-17,+mar. With the advent of multicolor fluorescence in situ hybridization (FISH) techniques, the prospect of accurately characterizing this complex karyotype became feasible. In the present study, we applied 24-color whole-chromosome painting and analyzed the results using a filter-based detection system and proprietary software for multiplex FISH (M-FISH). This resulted in the refinement of the karyotype and the identification of hitherto unsuspected chromosome rearrangements. M-FISH identified the origin of the add(8q) and add(11q) as well as the small marker chromosome. Both the del(7q) and del(12p) were redefined as unbalanced translocations and an apparently normal chromosome 11 was shown to be t(11;17). Importantly, the del(12p) was shown to be a der(12)t(7;12). Single-color whole-chromosome painting studies confirmed these findings, but also identified a cryptic t(Y;12) not seen in the original M-FISH analysis. We then carried out a FISH screening assay using a complete set of chromosome-specific subtelomeric probes. This allowed the identification of p and q subtelomeric regions involved in the translocations and indicated amplification of the 8q subtelomeric region. Comparative genomic hybridization (CGH) revealed a highly unbalanced karyotype, as deletions accompanied the majority of translocations, and identified the regions of amplification as 8q22.3-qter and 11q21-qter. Finally, conventional FISH with centromeric and unique sequence probes was necessary to elucidate all of the rearrangements.

Aged↗
PubMed1998

Molecular cytogenetic delineation of the critical deleted region in the 5q- syndrome.

The 5q- syndrome is a distinct type of myelodysplastic syndrome (MDS) characterised by refractory anaemia, morphological abnormalities of megakaryocytes, and del(5q) as the sole cytogenetic abnormality. In contrast to patients with therapy-related MDS with 5q deletions, 5q- syndrome patients have a favourable prognosis and a low rate of transformation to acute leukaemia. We have previously delineated a common deleted region of 5.6 Mb between the gene for fibroblast growth factor acidic (FGF1) and the subunit of interleukin 12 (IL12B) in two patients with 5q- syndrome and small deletions, del(5)(q31q33). The present study used fluorescence in situ hybridisation (FISH) analysis of these and a third 5q- syndrome patient with a small deletion, del(5)(q33q34), to refine further the critical deleted region. This resulted in the narrowing of the common deleted region within 5q31.3-5q33 to approximately 3 Mb, flanked by the adrenergic receptor beta 2 (ADRB2) and IL/2B genes. The common region of loss in these three 5q- syndrome patients includes the macrophage colony-stimulating factor-1 receptor (CSF1R), secreted protein, acidic, cysteine-rich (SPARC), and glutamate receptor (GR1A1) genes. This 5q- syndrome critical region is telomeric to and distinct from the other critical regions on 5q associated with MDS and acute myeloid leukaemia.

Adult↗
PubMed1998

Rapid mapping of markers applying vectorette technology to YAC fragmentation allows easy assembly of a high-density STS bacterial clone contig spanning the markers D6S1260-D6S1918.

We have generated a detailed physical map of the 6p21.3/p22.1 boundary, using a combination of yeast artificial chromosome (YAC) fragmentation and high-resolution sequence tagged site (STS) content mapping. YACs from the CEPH, St. Louis, and ICRF libraries have been used to construct a 4.5-Mb contig spanning the markers D6S306 to D6S1571. YAC insert sizes were determined by pulsed field gel electrophoresis (PFGE). Chimerism of YACs was determined by fluorescent in situ hybridization (FISH), and their integrity was determined by fingerprinting with Alu-PCR. We have identified 10 new CA repeat loci in this region as well as over 50 novel STSs, several tRNA genes, a new histone H2B gene and the phospholipase D gene. Using these new markers, we have rapidly generated a bacterial clone contig of over 250 kb, spanning the markers D6S1260 to D6S1918 (WI-3111) with STSs spaced on average every 6 kb.

Animals↗
PubMed1998

A comprehensive screen for TWIST mutations in patients with craniosynostosis identifies a new microdeletion syndrome of chromosome band 7p21.1.

Mutations in the coding region of the TWIST gene (encoding a basic helix-loop-helix transcription factor) have been identified in some cases of Saethre-Chotzen syndrome. Haploinsufficiency appears to be the pathogenic mechanism involved. To investigate the possibility that complete deletions of the TWIST gene also contribute to this disorder, we have developed a comprehensive strategy to screen for coding-region mutations and for complete gene deletions. Heterozygous TWIST mutations were identified in 8 of 10 patients with Saethre-Chotzen syndrome and in 2 of 43 craniosynostosis patients with no clear diagnosis. In addition to six coding-region mutations, our strategy revealed four complete TWIST deletions, only one of which associated with a translocation was suspected on the basis of conventional cytogenetic analysis. This case and two interstitial deletions were detectable by analysis of polymorphic microsatellite loci, including a novel (CA)n locus 7.9 kb away from TWIST, combined with FISH; these deletions ranged in size from 3.5 Mb to >11.6 Mb. The remaining, much smaller deletion was detected by Southern blot analysis and removed 2,924 bp, with a 2-bp orphan sequence at the breakpoint. Significant learning difficulties were present in the three patients with megabase-sized deletions, which suggests that haploinsufficiency of genes neighboring TWIST contributes to developmental delay. Our results identify a new microdeletion disorder that maps to chromosome band 7p21.1 and that causes a significant proportion of Saethre-Chotzen syndrome.

Acrocephalosyndactylia↗
PubMed1998

Del(18p) shown to be a cryptic translocation using a multiprobe FISH assay for subtelomeric chromosome rearrangements.

We have previously described a fluorescence in situ hybridisation (FISH) assay for the simultaneous analysis of all human subtelomeric regions using a single microscope slide. Here we report the use of this multiprobe FISH assay in the study of a patient whose karyotype was reported by G banding analysis as 46,XX,del(18)(p11.2). Although the proband had some features suggestive of a chromosomal abnormality, relatively few of the specific features of del(18p) were present. She was a 37 year old female with mild distal spinal muscular atrophy (SMA), arthritis of the hands, an abnormal chest shape (pectus excavatum), and an unusual skin condition (keratosis pilaris). Reverse chromosome painting with degenerate oligonucleotide primer-polymerase chain reaction (DOP-PCR) amplified del(18p) chromosomes as a probe confirmed the abnormality as del(18p), with no evidence of any other chromosome involvement. Subsequently, the multiprobe FISH assay confirmed deletion of 18p subtelomeric sequence. However, the assay also showed that sequences corresponding to the 2p subtelomeric probe were present on the tip of the shortened 18p. The patient is therefore monosomic for 18p11.2-pter and trisomic for 2p25-pter, and the revised karyotype is 46,XX,der(18)t(2;18)(p25; p11.2). We believe that a proportion of all cases reported as telomeric deletions may be cryptic translocations involving other chromosome subtelomeric regions. Further studies such as this are necessary to define accurately the clinical characteristics associated with pure monosomy in chromosomal deletion syndromes.

Adult↗
PubMed1998

Identification of new partner chromosomes involved in fusions with the ETV6 (TEL) gene in hematologic malignancies.

Several partner genes on different chromosomes have been reported to be fused with the ETV6 gene (located in chromosome band 12p13), with different breakpoints and different frequencies, in various hematologic malignancies, particularly acute myeloid and lymphoid leukemias and myelodysplastic syndromes. By using FISH and molecular analyses, we have analyzed five different pediatric and adult patients carrying cytogenetic abnormalities involving 12p13. Our findings demonstrate that ETV6 was rearranged in all the cases analyzed. In particular, ETV6 was disrupted by translocations with chromosomal bands 7q22, 7q36, 9q11, and 13q12, not previously described as partners of ETV6 in translocations, thus extending its promiscuity in rearranging with different partner genes.

Adult↗
PubMed1998

The in-vitro generation of dendritic cells from blast cells in acute leukaemia.

Dendritic cells (DC) are potent antigen-presenting cells responsible for the initiation of primary antigen-specific immune responses. In chronic myeloid leukaemia DC have been generated from Ph+ cells and these Ph+ DC are capable of stimulating cytolytic T-cell responses against the parent leukaemia cells. The prevalence of this phenomenon in acute leukaemia (AL) is unknown and we have therefore studied a variety of acute leukaemias to determine their potential for DC development. Peripheral blood mononuclear cells (PBMC) from 21 cases of AL were cultured in GM-CSF + TNF alpha. Of these cases, 15 were viable in culture and cells with typical DC morphology were observed in 12 of these 15 cases. DC growing in culture expressed either CDla and/or CD83 and were HLA-DR+ CD40+ CD80+ CD86+ typical of mature DC. In 9/12 cases the cultured cells possessed potent antigen-presenting capacity as measured in the allo-MLR. The malignant origin of the cultured DC was confirmed by FISH analysis in two cases (one 5q- and one Ph+ AL) and by persistent aberrant expression of CD19 in two cases of biphenotypic leukaemia. Functional DC may be derived from AL blasts in a significant number of patients and such DC may be capable of inducing leukaemia-specific immune responses with potential for clinically beneficial effects.

Acute Disease↗
PubMed1997

cDNA cloning of a human dishevelled DVL-3 gene, mapping to 3q27, and expression in human breast and colon carcinomas.

dishevelled (Dsh) is a member of the segment polarity gene family in Drosophila which plays an important role in the early developmental patterning processes. A human homologue of Dsh (DVL-1) has recently been described. Here, we report the cloning of a second human homologue of Dsh (called DVL-3) by cDNA library screening. The human DVL-3 gene encodes a predicted 716 amino acid protein which exhibits 98% amino acid identity with mouse Dvl-3 and 49% with Drosophila Dsh. DVL-3 was mapped to 3q27. The expression of DVL-3 mRNA was detected in 30 human cell lines and 2 primary cell cultures. DVL-3 mRNA was detected in normal human breast tissues (n = 4) and tumours (n = 25). Statistically, there was no difference in DVL-3 mRNA level between normal breast tissues and tumours. In human colorectal samples, DVL-3 was expressed equally in matched normal tissues, polyps and tumours. The data indicates that DVL-3 is widely expressed in human cells and supports the notion of a new developmental gene family for dishevelled which may have a widespread role in signal transduction.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Unbalanced t(3;12) in a case of juvenile myelomonocytic leukemia (JMML) results in partial trisomy of 3q as defined by FISH.

Juvenile myelomonocytic leukemia (JMML) is a rare disorder of early childhood, to which no recurrent chromosome rearrangement has been yet associated. We report a case where leukemic cells harbored a 46,XX,der(12)t(3;12) (q21 approximately 22;p13.33) karyotype, resulting in partial trisomy of 3q. The origin of chromosome material translocated to chromosome 12 was assessed by chromosome painting using a whole chromosome 3-specific probe. The breakpoint regions were defined by FISH using YAC probes from 3q and 12p chromosomal regions. Interestingly, partial trisomy of 3q has been detected in a previously reported JMML case, consequent to the presence of a der(15)t(3;15)(q13.1;q26). The involvement of a similar chromosome 3 rearrangement in these two JMML cases suggests the hypothesis that either the resulting duplication of some gene/s on 3q or the loss of heterozygosity (LOH) of some gene/s on 3p may be involved in one of the steps leading to JMML. On the other hand, it cannot be ruled out that the relevant mutation in our case might be consequent to the particular breakpoints at bands 3q21 approximately 22 and 12p13.3, that may alter the structure and/or expression of the involved gene/s.

Chromosome Aberrations↗
PubMed1997

Molecular-cytogenetic detection of a deletion of 1p36.3.

We report a deletion of 1p36.3 in a child with microcephaly, mental retardation, broad forehead, deep set eyes, depressed nasal bridge, flat midface, relative prognathism, and abnormal ears. The phenotype is consistent with that described for partial monosomy for 1p36.3. Reverse chromosome painting and microsatellite and Southern blot analyses were used to map the extent of the deletion. Fluorescence in situ hybridisation (FISH) analysis using probes from every telomere indicates that the rearrangement is likely to be a chromosomal truncation or rearrangement involving subtelomeric repetitive DNA. The deletion was identified by screening a sample of children and adults with idiopathic mental retardation. In conjunction with previous work on this sample, we estimate that 7.4% of the group have subtelomeric rearrangements.

Adolescent↗
PubMed1996

The mouse homologue of the polycystic kidney disease gene (Pkd1) is a single-copy gene.

The mouse homologue of the polycystic kidney disease 1 gene (PKD1) was mapped to chromosome 17 using somatic cell hybrids, B x D recombinant inbred strains, and FISH. The gene is located within a previously defined conserved synteny group that includes the mouse homologue of tuberous sclerosis 2 (TSC2) and is linked to the alpha globin pseudogene Hba-ps4. Although the human genome contains multiple copies of genes related to PKD1, there is no evidence for more than one copy in the mouse genome. Like their human counterparts, the mouse Tsc2 and Pkd1 genes are arranged in a tail-to-tail orientation with a distance of only 63 bp between the polyadenylation signals of the two genes.

Animals↗
PubMed1996

Chromosomal stabilisation by a subtelomeric rearrangement involving two closely related Alu elements.

We have characterised a subtelomeric rearrangement involving the short arm of chromosome 16 that gives rise to alpha-thalassaemia by deleting the major, remote regulatory element controlling alpha-globin expression. The chromosomal breakpoint lies in an Alu family repeat located only approximately 105 kb from the 16p subtelomeric region. The broken chromosome has been stabilised with a newly positioned telomere acquired by recombination between this 16p Alu element and a closely related subtelomeric Alu element of the Sx subfamily. It seems most likely that this abnormal chromosome has been rescued by the mechanism of telomere capture which may reflect a more general process by which subtelomeric sequences are normally dispersed between chromosomal ends.

Adolescent↗
PubMed1996

Classification of deletions and identification of cryptic translocations involving 7q by fluorescence in situ hybridization (FISH).

Monosomy 7 (-7) and deletion of the long arm of chromosome 7, del(7q), are frequent non-random findings in the myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML), particularly associated with therapy-related disease (t-MDS and t-AML). The cytogenetic breakpoints of 7q deletions are variable, with both terminal and interstitial deletions reported. It is now believed that most deletions are interstitial, and that the variability in reported breakpoints may be due to the difficulty in determining whether the terminal, pale staining G band is present. It has also been suggested that some reported deletions of 7q may be cryptic translocations. To address these questions, we carried out fluorescence in situ hybridization (FISH) studies on leukaemic cells from a large series of patients using a chromosome 7-specific paint and a 7q telomere-specific probe. Of the 26 cases studied, seven were 'pure' deletions (ie without the involvement of other chromosomes); four were interstitial and two terminal. One further patient had two clones each with a different deletion: one with a terminal del(7)(q22) and the second with an interstitial del(7)(q32-qter). A further nine cases had unbalanced translocations with deletion of 7q terminal sequences. The remaining 10 cases were translocations and complex rearrangements, some involving interstitial deletions of 7q. In two cases in which del(7q) was reported as the sole cytogenetic abnormality by G-banding, FISH revealed cryptic translocations involving 7q.

Adult↗
PubMed1995

Characterization and variation of a human inwardly-rectifying-K-channel gene (KCNJ6): a putative ATP-sensitive K-channel subunit.

The ATP-sensitive K-channel plays a central role in insulin release from pancreatic beta-cells. We report here the cloning of the gene (KCNJ6) encoding a putative subunit of a human ATP-sensitive K-channel expressed in brain and beta-cells, and characterisation of its exon-intron structure. Screening of a somatic cell mapping panel and fluorescent in situ hybridization place the gene on chromosome 21 (21q22.1-22.2). Analysis of single-stranded conformational polymorphisms revealed the presence of two silent polymorphisms (Pro-149: CCG-CCA and Asp-328: GAC-GAT) with similar frequencies in normal and non-insulin-dependent diabetic patients.

Adenosine Triphosphate↗