Comparing human genome mapping data.
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Chromosomes, Human, Pair 4↗
Biomedical subjects
K L Evans
Publications and source records attributed to K L Evans.
Markers close to the dopamine D5 receptor gene (DRD5) show significant association with schizophrenia but not bipolar disorder.
Following the description of linkage of markers at chromosome 4p16 to bipolar disorder in several families [Blackwood et al., 1996], and the association of the alleles of a polymorphism closely linked to D5 dopamine receptor gene with schizophrenia [Williams et al., 1997], we have looked for linkage disequilibrium between a series of microsatellite markers from this region and major psychoses including schizophrenia, bipolar disorder, and unipolar major depressive disorder. A significant increase in the frequency of the 148 bp allele of DRD5 (P = 0.024) and the 244 bp allele of D4S615 (P = 0.001) was found in patients with schizophrenia (n = 158 DRD5; n = 133 D4S615), compared with patients with bipolar disorder (n = 270 DRD5; n = 107 D4S615), or controls without psychiatric illness (n = 437 DRD5; n = 309 D4S615). The frequency of the 148 bp allele of DRD5 was also increased in schizophrenia over unipolar major depressive disorder (n = 65). D4S615 was not typed in unipolar disorder. The estimated odds ratios confirmed that the 148 bp allele of DRD5 and the 244 bp allele of D4S615 conferred increased risk of schizophrenia. Estimated Haplotype (EH) analysis of 174 controls and 128 patients with schizophrenia who were typed for both markers confirmed the strong associations with these alleles but did not show evidence that the markers were in linkage disequilibrium with each other even though they lie approximately 150 kb apart. The data are consistent with an association between markers close to the D5 dopamine receptor and schizophrenia, but not bipolar disorder or unipolar major depression.
Alleles↗
Twin peaks: the draft human genome sequence.
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Computational Biology↗
A 6.9-Mb high-resolution BAC/PAC contig of human 4p15.3-p16.1, a candidate region for bipolar affective disorder.
Bipolar affective disorder (BPAD) is a complex disease with a significant genetic component and a population lifetime risk of 1%. Our previous work identified a region of human chromosome 4p that showed significant linkage to BPAD in a large pedigree. Here, we report the construction of an accurate, high-resolution physical map of 6.9 Mb of human chromosome 4p15.3-p16.1, which includes an 11-cM (5.8 Mb) critical region for BPAD. The map consists of 460 PAC and BAC clones ordered by a combination of STS content analysis and restriction fragment fingerprinting, with a single approximately 300-kb gap remaining. A total of 289 new and existing markers from a wide range of sources have been localized on the contig, giving an average marker resolution of 1 marker/23 kb. The STSs include 57 ESTs, 9 of which represent known genes. This contig is an essential preliminary to the identification of candidate genes that predispose to bipolar affective disorder, to the completion of the sequence of the region, and to the development of a high-density SNP map.
Bipolar Disorder↗
Nuts and bolts of psychiatric genetics: building on the Human Genome Project.
Schizophrenia and bipolar affective disorder are chronic, disabling illnesses that together affect 2% of the population. Genetic factors are known to be important in their development, but there are, as yet, no confirmed susceptibility genes. Here we discuss important issues in terms of alternative genetic strategies (linkage, association and/or cytogenetics) in the identification of candidate genes for the major psychoses. We discuss the impact of the Human Genome Project, the role of comparative genetics in finding and testing positional candidates, and the prospects for rational drug design and personalized medicine.
Female↗
Physical mapping: integrating computational and molecular genetic data.
A crucial step beyond the identification of genetic linkage of a disease to a chromosomal region is the production of a physical map that will allow the identification of candidate genes. Although the process of physical map building has been facilitated by the flow of data released by the Human Genome Project, gathering all the information together requires significant effort. In a previous study, we reported linkage between Bipolar Affective Disorder and the chromosomal location 4p15.3--p16.1. In this review we use this example to describe how to collect publicly available sequence, DNA fingerprint, and genetic marker data and integrate these with empirical data to build a large scale high resolution physical map of a region. Methods used to identify new genetic markers and candidate genes within a circumscribed region are also presented.
Databases, Factual↗
Mechanisms of regulation of agonist efficacy at the 5-HT(1A) receptor by phospholipid-derived signaling components.
The 5-hydroxytryptamine (5-HT)(1A) receptor system plays a prominent role in a variety of physiological functions and behaviors and regulation of the responsiveness of this receptor system has been implicated in the therapeutic mechanism of action of the selective serotonin reuptake inhibitor class of antidepressant drugs. Here we report that the responsiveness of the 5-HT(1A) receptor system is regulated by consequences of activation of the phospholipase A(2) (PLA(2)) and phospholipase C effector pathways. In Chinese hamster ovary cells stably expressing the human 5-HT(1A) receptor, 5-HT(1A) receptor-mediated inhibition of forskolin-stimulated cAMP accumulation was reduced by a cyclooxygenase-dependent arachidonic acid (AA) metabolite produced in response to exogenously applied AA or activation of PLA(2) directly with melittin or indirectly by receptor activation. This effect of the AA metabolite was sensitive to the activation state of adenylyl cyclase suggesting that the target of the AA metabolite-induced reduction in 5-HT(1A) responsiveness was adenylyl cyclase. Activation of protein kinase C with a phorbol ester also reduced 5-HT(1A) receptor function. In contrast, increases in intracellular calcium levels via a calcium ionophore or thapsigargin enhanced 5-HT(1A) responsiveness. The net effect of activation of phospholipid-coupled receptors on 5-HT(1A) agonist efficacy depended upon the relative capacity to produce these positive (calcium) and negative (AA) regulators. These data demonstrate that the responsiveness of the 5-HT(1A) receptor system can be enhanced or depressed by consequences of activation of phospholipid-coupled receptor systems. An understanding of the cellular mechanisms for regulation of 5-HT(1A) function may lead to novel targets for development of psychotherapeutic drugs.
Adenylyl Cyclases↗
Mutational analysis of the Wolfram syndrome gene in two families with chromosome 4p-linked bipolar affective disorder.
Bipolar affective disorder (BPAD) is a complex disease with a significant genetic component. Heterozygous carriers of Wolfram syndrome (WFS) are at increased risk of psychiatric illness. A gene for WFS (WFS1) has recently been cloned and mapped to chromosome 4p, in the general region we previously reported as showing linkage to BPAD. Here we present sequence analysis of the WFS1 coding sequence in five affected individuals from two chromosome 4p-linked families. This resulted in the identification of six polymorphisms, two of which are predicted to change the amino acid sequence of the WFS1 protein, however none of the changes segregated with disease status. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:158-160, 2000.
Bipolar Disorder↗
Clues to the cause of neurodegeneration.
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Animals↗
In silico identification of transcripts and SNPs from a region of 4p linked with bipolar affective disorder.
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Bipolar Disorder↗
Subtilisins of Bacillus spp. hydrolyze keratin and allow growth on feathers.
Keratinase is a serine protease produced by Bacillus licheniformis PWD-1 that effectively degrades keratin and confers the ability to grow on feathers to a protease-deficient B. subtilis strain. Studies presented herein demonstrate that B. licheniformis Carlsberg strain NCIMB 6816, which produces the well-characterized serine protease subtilisin Carlsberg, also degrades and grows on feathers. The PWD-1 and Carlsberg strains showed a similar time-course of enzyme production, and the purified serine proteases have similar enzymatic properties on insoluble azokeratin and soluble FITC-casein. Kinetic analysis of both enzymes demonstrated that they have high specificity for aromatic and hydrophobic amino acids in the P1 substrate position, although keratinase discriminates more than subtilisin Carlsberg against charged residues at this site. Nucleotide sequence analysis of the serine protease genes from B. licheniformis strains PWD-1, Carlsberg NCIMB 6816, ATCC 12759, and NCIMB 10689 showed that the kerA-encoded protease of PWD-1 differs from the others only by having V222, rather than A222, near the active site serine S220. Further, high-level expression of subE-encoded subtilisin from B. subtilis (78% similar to subtilisin Carlsberg) also confers growth on feathers on a protease-deficient B. subtilis strain. While strain PWD-1 and the kerA protease efficiently degrade keratin, keratin hydrolysis and growth on feathers is a property that can be conferred by appropriate expression of the major subtilisins, including the industrially produced enzymes.
Animals↗
Recognition and management of sinusitis.
Acute sinusitis frequently follows upper respiratory tract infections. Patients complain of headache, facial pain, fever and purulent rhinorrhoea. Diagnosis is based upon the symptoms, and treatment comprises symptomatic relief with analgesics, topical or systemic decongestants and steam inhalation. If indicated, antibiotics should be given for an adequate period of time. Patients with chronic sinusitis complain of a combination of nasal obstruction, rhinorrhoea and postnasal drip associated with intermittent facial pain, with symptoms persisting for 3 months or more. Predisposition to the condition may be caused by rhinitis (allergic or nonallergic) and anatomical variants. Failure of mucociliary transport and sinus ostial obstruction leads to mucosal oedema, mucous hypersecretion and chronic infection. Current treatment aims are to control rhinitis and improve ventilation and function of the sinuses. Rhinitis may be controlled with the long term use of topical corticosteroids, mast cell stabilisers or antihistamines, either alone or in combination. Secretions may be cleared with steam inhalation and/or saline nasal douching. Failure to control chronic sinusitis with medical treatment may indicate surgery. The aim of surgery is to improve ventilation and facilitate drainage of the sinuses, allowing the restoration of normal function. Removal of nasal polyps, reduction of inferior turbinates or septal straightening may be all that is required. Some patients will need endoscopic ethmoidectomy and middle meatal antrostomy. Improved ventilation in the ethmoid infundibulum may help to resolve disease in maxillary and frontal sinuses. Medical treatment of underlying rhinitis will need to be continued postoperatively, often in the long term, while special consideration needs to be paid to sinusitis in children, in relation to dental disease and in the immunosuppressed. Complications of acute and chronic sinusitis include intraorbital and intracranial sepsis. These potentially lethal complications need urgent evaluation with high resolution computerised tomography (CT) scanning, intravenous administration of broad spectrum antibiotics (including anaerobic and microaerophilic cover) and urgent surgical drainage as appropriate.
AIDS-Related Opportunistic Infections↗
Novel transcribed sequences neighbouring a translocation breakpoint associated with schizophrenia.
A 1.3Mb chromosome 11-specific yeast artificial chromosome (YAC) that spans a t(1;11) translocation breakpoint associated with major psychosis has been used to enrich cDNAs that are encoded within it and expressed in the human foetal brain. Database analysis of the selected fragments led to the identification of 54 clones matching alpha-tubulin, 4 fragments matching two anonymous human expressed sequence tags (ESTs) and 8 fragments giving no database matches. The clones matching alpha-tubulin led to the identification of a novel alpha-tubulin locus located approximately 250 kb proximal to the translocation breakpoint. Extensive sequence and expression analysis of this locus suggests that this is a processed pseudogene, although a long open reading frame is maintained and the possibility that an abnormally acting protein may be expressed in a highly tissue or developmental specific manner cannot be discounted. The novel cDNA fragments map up to 700 kb proximal to the translocation breakpoint and are associated with potential CpG islands. Reverse transcriptase polymerase chain reaction (RT-PCR) expression analysis and high resolution genomic mapping suggest that they may comprise up to three novel genes. No major disruption of the identified fragments could be detected in the genomic DNA of translocation carriers. The psychosis associated with this translocation may therefore be due to position effects on the transcription of these genes or an involvement of translocated chromosome 1 sequences.
Chromosomes, Artificial, Yeast↗
A contiguous clone map over 3 Mb on the long arm of chromosome 11 across a balanced translocation associated with schizophrenia.
Forty-nine clones derived by microdissection of a schizophrenia-associated t(1;11)(q42.1;q14.3) breakpoint region have been assigned by somatic cell hybrid mapping to seven discrete intervals on the long arm of human chromosome 11. Eleven of the clones were shown to map to a small region immediately distal to the translocation breakpoint on 11q. A 3-Mb contiguous clone map of this region was established by isolation of corresponding YAC recombinants. The contig was oriented and shown to traverse the translocation breakpoint by FISH and microsatellite marker analysis. This contig will facilitate the isolation of candidate sequences whose expression may be affected by the translocation.
Base Sequence↗
Management of posterior laryngeal and laryngotracheoesophageal clefts.
OBJECTIVE: To review the clinical features, associated congenital abnormalities, management, and morbidity of infants presenting with posterior laryngeal and laryngotracheal clefts. DESIGN: Case series. SETTING: Great Ormond Street Hospital for Sick Children NHS Trust, London, England. PATIENTS: Consecutive sample of 44 patients presenting with posterior laryngeal and laryngotracheal clefts between December 10, 1979, and January 30, 1992. MAIN OUTCOME MEASURES: Clinical features, incidence of surgery, and associated morbidity and mortality related to different types of airway cleft. RESULTS: The main presenting features were stridor and aspiration, which were more evident with the more extensive clefts. Twenty-five patients (56%) had associated congenital abnormalities. Fourteen patients (32%) were treated conservatively. Sixteen patients (36%) underwent primary endoscopic surgical repair. Eight patients (18%) underwent primary repair via an anterior laryngofissure; and six patients (14%) underwent primary repair via a lateral pharyngotomy. Eight patients (18%) required revision surgery, two (4%) of them on more than one occasion. Ten patients (23%) required fundoplication to control gastroesophageal reflux. Six patients (14%) died. CONCLUSIONS: The identification of an airway cleft requires a high index of suspicion. Morbidity and mortality are reduced by securing the airway, controlling gastroesophageal reflux, and using a multidisciplinary pediatric team. We recommend the anterior laryngofissure because of the ease of surgical access.
Abnormalities, Multiple↗
Identifying genes within microdissected genomic DNA: isolation of brain expressed genes from a translocation region associated with inherited mental illness.
An improved protocol has been developed for physical enrichment of cDNA sequences by hybridization to genomic DNA. When applied to microdissection recombinants derived from a translocation breakpoint region associated with inherited mental illness, a single cycle of the procedure permitted enriched cDNAs to be visualized directly by agarose gel electrophoresis. Hybridization screening of a library of clones derived from the enriched cDNAs, employing the genomic resource as a probe, led to the identification of six novel gene fragments. This general approach to the isolation of regionally encoded genes could be applied to any subchromosomal interval as a first step towards global transcription map construction.
Animals↗
Direct microdissection and microcloning of a translocation breakpoint region, t(1;11)(q42.2;q21), associated with schizophrenia.
We describe the generation of large-fragment microclone libraries from the chromosomal breakpoint of a reciprocal balanced translocation linked to schizophrenia. The abnormality was visible under the phase-contrast microscope, allowing direct dissection from unstained, unbanded metaphases. Two separate microdissection experiments yielded 443 and 672 recombinants, respectively. Following complete EcoRI digestion, inserts with an average size of 0.3 kb (range, 0.2-3 kb) were obtained in the first experiment and 1.5 kb (range, 0.15-6.5 kb) in the second. FISH analysis of pooled clones "painted" back onto the derivative chromosome and assignment of microclones to somatic cell hybrids confirmed the fidelity of the method. Microdissection of chromosome regions identified by karyotype rearrangements in unstained, unbanded metaphases is a potentially powerful tool for positional cloning.
Base Sequence↗
Regional localisation of 19 brain expressed sequence tags to human chromosome 11 using PCR amplification of somatic cell hybrid DNAs.
Expressed sequence tags (ESTs) provide an efficient route to the identification of genes involved in normal development and in disease. PCR amplification of somatic cell hybrid DNAs was used to localise 22 brain-derived ESTs to subregions of human chromosome 11. Problems encountered with the standardised PCR conditions were overcome by optimising the annealing temperatures and the use of "touchdown" PCR. Amplification of the correct target sequence allowed the mapping of 19 ESTs, 8 to the short arm and 11 to the long arm of chromosome 11. No definitive localisation could be determined for the three remaining ESTs.
Animals↗