Showing papers in "Nature Genetics in 1992"
TL;DR: In this paper, a consensus binding site with a striking internal symmetry was identified, consisting of two copies of the 10 base pair motif 5′-PuPuC(A/T)(T/A)GPyPyPy-3′ separated by 0-13 base pairs.
Abstract: Recent experiments have suggested that p53 action may be mediated through its inter action with DNA. We have now identified 18 human genomic clones that bind to p53 in vitro. Precise mapping of the binding sequences within these clones revealed a consensus binding site with a striking internal symmetry, consisting of two copies of the 10 base pair motif 5′-PuPuPuC(A/T)(T/A)GPyPyPy-3′ separated by 0-13 base pairs. One copy of the motif was insufficient for binding, and subtle alterations of the motif, even when present in multiple copies, resulted in loss of affinity for p53. Mutants of p53, representing each of the four “hot spots” frequently altered in human cancers, failed to bind to the consensus dimer. These results define the DNA sequence elements with which p53 interacts in vitro and which may be important for p53 action in vivo.
1,996 citations
TL;DR: A double mutation at codons 670 and 671 (APP 770 transcript) in exon 16 which co–segregates with the disease in two large (probably related) early–onset Alzheimer's disease families from Sweden is identified.
Abstract: Mutations at codon 717 in exon 17 of the beta-amyloid precursor protein (APP) gene have previously been shown to segregate with early onset Alzheimer's disease in some families. We have identified a double mutation at codons 670 and 671 (APP 770 transcript) in exon 16 which co-segregates with the disease in two large (probably related) early-onset Alzheimer's disease families from Sweden. Two base pair transversions (G to T, A to C) from the normal sequence predict Lys to Asn and Met to Leu amino acid substitutions at codons 670 and 671 of the APP transcript. This mutation occurs at the amino terminal of beta-amyloid and may be pathogenic because it occurs at or close to the endosomal/lysosomal cleavage site of the molecule. Thus, pathogenic mutations in APP frame the beta-amyloid sequence.
1,626 citations
TL;DR: A large pedigree in which NIDDM is identified, in combination with a sensorineural hearing loss, is maternally inherited, and the maternal inheritance and the observed decrease in mitochondrial enzyme activities of the respiratory chain indicate a genetic defect in the mitochondrial DNA.
Abstract: Non-insulin-dependent (type II) diabetes mellitus (NIDDM) is characterized by hyperglycaemia and insulin resistance, and affects nearly 5% of the general population. Inherited factors are important for its development, but the genes involved are unknown. We have identified a large pedigree in which NIDDM, in combination with a sensorineural hearing loss, is maternally inherited. The maternal inheritance and the observed decrease in mitochondrial enzyme activities of the respiratory chain indicate a genetic defect in the mitochondrial DNA. An A to G transition was identified at nucleotide 3,243, a conserved position in the mitochondrial gene for tRNA(Leu)(UUR). This mutation cosegregates with the disease in this family and is absent in controls, and indicates that a point mutation in mitochondrial DNA is a pathogenetic factor for NIDDM.
1,093 citations
TL;DR: Changes in the accumulation of the common 4977 nucleotide pair (np) deletion in the cortex, putamen and cerebellum suggest that somatic mtDNA deletions might contribute to the neurological impairment often associated with ageing.
Abstract: We have examined the role of somatic mitochondrial DNA (mtDNA) mutations in human ageing by quantitating the accumulation of the common 4977 nucleotide pair (np) deletion (mtDNA4977) in the cortex, putamen and cerebellum. A significant increase in the mtDNA4977 deletion was seen in elderly individuals. In the cortex, the deleted to total mtDNA ratio ranged from 0.00023 to 0.012 in 67-77 year old brains and up to 0.034 in subjects over 80. In the putamen, the deletion level ranged from 0.0016 to 0.010 in 67 to 77 years old up to 0.12 in individuals over the age of 80. The cerebellum remained relatively devoid of mtDNA deletions. Similar changes were observed with a different 7436 np deletion. These changes suggest that somatic mtDNA deletions might contribute to the neurological impairment often associated with ageing.
862 citations
TL;DR: A novel base mutation in the same exon of the APP gene which co–segregates in one family with presenile dementia and cerebral haemorrhage due to cerebral amyloid angiopathy is reported, suggesting that the clinically distinct entities can be caused by the same mutation.
Abstract: Several families with an early-onset form of familial Alzheimer's disease have been found to harbour mutations at a specific codon (717) of the gene for the beta-amyloid precursor protein (APP) on chromosome 21. We now report, a novel base mutation in the same exon of the APP gene which co-segregates in one family with presenile dementia and cerebral haemorrhage due to cerebral amyloid angiopathy. The mutation results in the substitution of alanine into glycine at codon 692. These results suggest that the clinically distinct entities, presenile dementia and cerebral amyloid angiopathy, can be caused by the same mutation in the APP gene.
775 citations
TL;DR: The data suggest mechanisms whereby defects in CFTR expression could lead to abnormal production of mucus in human lung, particularly in non–CF individuals.
Abstract: We have used in situ hybridization and immunocytochemistry to characterize the cellular distribution of cystic fibrosis (CF) gene expression in human bronchus. The cystic fibrosis transmembrane conductance regular (CFTR) was primarily localized to cells of submucosal glands in bronchial tissues from non-CF individuals notably in the serous component of the secretory tubules as well as a subpopulation of cells in ducts. Normal distribution of CFTR mRNA was found in CF tissues while expression of CFTR protein was genotype specific, with delta F508 homozygotes demonstrating no detectable protein and compound heterozygotes expressing decreased levels of normally distributed protein. Our data suggest mechanisms whereby defects in CFTR expression could lead to abnormal production of mucus in human lung.
660 citations
TL;DR: Findings indicate that the human aniridia and murine Small eye phenotypes arise from homologous defects in PAX6, a gene containing paired–box and homeobox motifs that is specifically expressed in the developing eye and brain.
Abstract: Aniridia is a semidominant disorder in which development of the iris, lens, cornea and retina is disturbed. The mouse mutation Small eye (Sey), which has been proposed as a model for aniridia, results from defects in Pax–6, a gene containing paired–box and homeobox motifs that is specifically expressed in the developing eye and brain. To test the role of PAX6 in aniridia, we isolated human cDNA clones and determined the intron–exon structure of this gene. PAX6 spans 22 kilobases and is divided into 14 exons. Analysis of DNA from 10 unrelated aniridia patients revealed intragenic mutations in three familial and one sporadic case. These findings indicate that the human aniridia and murine Small eye phenotypes arise from homologous defects in PAX6.
636 citations
TL;DR: A pedigree with maternally transmitted DM and deafness for mitochondrial DNA mutations was tested and a 10.4 kilobase mtDNA deletion was discovered, demonstrating that DM can be caused by mtDNA mutations and suggests that some of the heterogeneity of this disease results from the novel features of mtDNA genetics.
Abstract: Diabetes mellitus (DM) is one of the most common chronic disorders of children and adults. Several reports have suggested an increased incidence of maternal transmission in some forms of DM. Therefore, we tested a pedigree with maternally transmitted DM and deafness for mitochondrial DNA mutations and discovered a 10.4 kilobase (kb) mtDNA deletion. This deletion is unique because it is maternally inherited, removes the light strand origin (OL) of mtDNA replication, inhibits mitochondrial protein synthesis, and is not associated with the hallmarks of mtDNA deletion syndromes. This discovery demonstrates that DM can be caused by mtDNA mutations and suggests that some of the heterogeneity of this disease results from the novel features of mtDNA genetics.
608 citations
TL;DR: Observations indicate that FSHD is caused by independent de novo DNA rearrangements in the EcoRI fragment detected by p13E–11, and in 10 Dutch families analysed, a specific shorter fragment between 14–28 kb co–segregates with FSHd.
Abstract: Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant neuromuscular disorder which maps to chromosome 4qter, distal to the D4S139 locus. The cosmid clone 13E, isolated in a search for homeobox genes, was subsequently mapped to 4q35, also distal to D4S139. A subclone, p13E-11, detects in normal individuals a polymorphic EcoRI fragment usually larger than 28 kilobases (kb). Surprisingly, using the same probe we detected de novo DNA rearrangements, characterized by shorter EcoRI fragments (14-28 kb), in 5 out of 6 new FSHD cases. In 10 Dutch families analysed, a specific shorter fragment between 14-28 kb cosegregates with FSHD. Both observations indicate that FSHD is caused by independent de novo DNA rearrangements in the EcoRI fragment detected by p13E-11.
606 citations
TL;DR: Using classical methods for analysing bacterial cultures, striking linkage disequilibrium for diastrophic dysplasia in Finland is reported, indicating that the DTD gene should lie within 0.06 centimorgans of the CSF1R gene.
Abstract: Linkage disequilibrium mapping in isolated populations provides a powerful tool for fine structure localization of disease genes. Here, Luria and Delbruck's classical methods for analysing bacterial cultures are adapted to the study of human isolated founder populations in order to estimate (i) the recombination fraction between a disease locus and a marker; (ii) the expected degree of allelic homogeneity in a population; and (iii) the mutation rate of marker loci. Using these methods, we report striking linkage disequilibrium for diastrophic dysplasia (DTD) in Finland indicating that the DTD gene should lie within 0.06 centimorgans (or about 60 kilobases) of the CSF1R gene. Predictions about allelic homogeneity in Finland and mutation rates in simple sequence repeats are confirmed by independent observations.
564 citations
TL;DR: Mutations in the Pax–6 gene are described in two cases of sporadic aniridia, one detected at the DNA level and one at the RNA level, both of which are predicted to affect protein function.
Abstract: Aniridia is an inherited ocular disorder of variable expressivity characterized by iris hypoplasia. A candidate aniridia gene, AN, which is the human homologue of the mouse Pax-6 gene, has recently been isolated by positional cloning from the WAGR region of 11p13. Here we describe mutations in this gene in two cases of sporadic aniridia, one detected at the DNA level and one at the RNA level, both of which are predicted to affect protein function. Mutations in Pax-6 have been described previously in Small eye, the proposed mouse model for aniridia. We present new phenotypic evidence for the validity of this mouse model.
TL;DR: The large–scale sequencing of a 3′–directed cDNA library from the human liver cell line HepG2, that is a non–biased representation of the mRNA population, is initiated, providing a complementary approach to structural analysis of the human genome by generating expressed sequence tags (ESTs).
Abstract: Large scale sequencing of cDNAs provides a complementary approach to structural analysis of the human genome by generating expressed sequence tags (ESTs). We have initiated the large-scale sequencing of a 3'-directed cDNA library from the human liver cell line HepG2, that is a non-biased representation of the mRNA population. 982 random cDNA clones were sequenced yielding more than 270 kilobases. A significant portion of the identified genes encoded secretable proteins and components for protein-synthesis. The abundance of cDNA species varied from 2.2% to less than 0.004%. Fifty two percent of the mRNA were abundant species consisting of 173 genes and the rest were non-abundant, consisting of about 6,600 genes.
TL;DR: An analysis of a series of leukaemic patients carrying t(4;11 and t(9;11) translocations indicate that the majority of breakpoints in infant leukaemias lie within a 5 kb region.
Abstract: Some acute lymphocytic leukaemias, particularly those in young children, are associated with a t(4;11)(q21;q23) reciprocal translocation. We have cloned the translocation breakpoint on chromosome 11q23 and isolated corresponding RNA transcripts from this region. The translocation occurs within a cluster of Alu repetitive elements located within an intron of a gene that gives rise to 11.5 (kb) transcript spanning the translocation breakpoint. The 11.5 kb transcript encodes a protein that is highly homologous to the Drosophila trithorax gene, a developmental regulator. An analysis of a series of leukaemic patients carrying t(4;11) and t(9;11) translocations indicate that the majority of breakpoints in infant leukaemias lie within a 5 kb region.
TL;DR: It is suggested that a gene dosage effect involving PMP–22 is at least partially responsible for the demyelinating neuropathy seen in CMT1A.
Abstract: Charcot-Marie-Tooth disease type 1A (CMT1A) is an autosomal dominant peripheral neuropathy associated with a large DNA duplication on the short arm of human chromosome 17. The trembler (Tr) mouse serves as a model for CMT1A because of phenotypic similarities and because the Tr locus maps to mouse chromosome 11 in a region of conserved synteny with human chromosome 17. Recently, the peripheral myelin gene Pmp-22 was found to carry a point mutation in Tr mice. We have isolated cDNA and genomic clones for human PMP-22. The gene maps to human chromosome 17p11.2-17p12, is expressed at high levels in peripheral nervous tissue and is duplicated, but not disrupted, in CMT1A patients. Thus, we suggest that a gene dosage effect involving PMP-22 is at least partially responsible for the demyelinating neuropathy seen in CMT1A.
TL;DR: Targeted gene expression has been achieved in the liver, albeit at low levels, suggesting that adenovirus vectors may be a useful means for in vivo gene therapy in liver disorders.
Abstract: Replication deficient, recombinant adenovirus (Ad) vectors do not require target cell replication for transfer and expression of exogenous genes and thus may be useful for in vivo gene therapy in hepatocytes. In vitro, primary cultures of rat hepatocytes infected with a recombinant Ad containing a human α1–antitrypsin cDNA (Ad–α1AT) synthesized and secreted human α1 AT for 4 weeks. In rats, in vivo intraportal administration of a recombinant Ad containing the E. coli lacZ gene, was followed by expression of β–galactosidase in hepatocytes 3 days after infection. Intraportal infusion of Ad–α1AT produced detectable serum levels of human α1AT for 4 weeks. Thus, targeted gene expression has been achieved in the liver, albeit at low levels, suggesting that adenovirus vectors may be a useful means for in vivo gene therapy in liver disorders.
University of Toronto1, Harvard University2, Russian Academy3, University of Florence4, University of Turin5, Duke University6, École pratique des hautes études7, University of Massachusetts Medical School8, Novartis9, National Institutes of Health10, University of Milan11, Tohoku University12, Boston University13, Mount Sinai Hospital14
TL;DR: Evidence is provided for a major early onset FAD locus on the long arm of chromosome 14 near the markers D14S43 and D 14S53 and it is suggested that the inheritance of FAD may be more complex than had initially been suspected.
Abstract: Familial Alzheimer's disease (FAD) has been shown to be genetically heterogeneous, with a very small proportion of early onset pedigrees being associated with mutations in the amyloid precursor protein (APP) gene on chromosome 21, and some late onset pedigrees showing associations with markers on chromosome 19. We now provide evidence for a major early onset FAD locus on the long arm of chromosome 14 near the markers D14S43 and D14S53 (multipoint lod score z = 23.4) and suggest that the inheritance of FAD may be more complex than had initially been suspected.
TL;DR: Mixed populations of a CF airway cell line expressing either the normal cystic fibrosis transmembrane conductance regulator (CFTR) cDNA (corrected cells) or a reporter gene in defined percentages suggest that in vivo correction of allCF airway cells may not be mandatory.
Abstract: An important issue for in vivo gene therapy for cystic fibrosis (CF) is the percentage of cells within the CF airway that will require correction. In this study, we mixed populations of a CF airway cell line expressing either the normal cystic fibrosis transmembrane conductance regulator (CFTR) cDNA (corrected cells) or a reporter gene in defined percentages. As few as 6–10% corrected cells within an epithelial sheet generated Cl− transport properties similar to sheets comprised of 100% corrected cells. Cell–cell coupling may serve as the mechanism for amplification of the functional effects of corrected cells. These data suggest that in vivo correction of all CF airway cells may not be mandatory.
TL;DR: This null mutation, the first gene defect identified in autosomal recessive retinitis pigmentosa, should result in a functionally inactive rhodopsin protein that is missing the sixth and seventh transmembrane domains including the 11–cis–retinal attachment site.
Abstract: Mutations within the rhodopsin gene are known to give rise to autosomal dominant retinitis pigmentosa (RP), a common hereditary form of retinal degeneration. We now describe a patient with autosomal recessive RP who is homozygous for a nonsense mutation at codon 249 within exon 4 of the rhodopsin gene. This null mutation, the first gene defect identified in autosomal recessive retinitis pigmentosa, should result in a functionally inactive rhodopsin protein that is missing the sixth and seventh transmembrane domains including the 11-cis-retinal attachment site. We also found a different null mutation carried heterozygously by an unrelated unaffected individual. Heterozygous carriers of either mutation had normal ophthalmologic examinations but their electroretinograms revealed an abnormality in rod photoreceptor function.
TL;DR: In four multiple case breast-ovarian cancer families, it is found that in each of nine tumours which showed allele losses, the losses were from the wild–type chromosome, suggesting that the putative ‘breast–ovarian’ cancer gene is indeed a tumour suppressor gene.
Abstract: A predisposing gene for breast and ovarian cancer has recently been mapped to chromosome 17q12-21. If this gene is a tumour suppressor gene, allele losses would be expected in the tumours of affected family members and the losses should affect the wild-type chromosome, reflecting the need for inactivation of the wild-type allele at the predisposing locus. In four multiple case breast-ovarian cancer families, we have found that in each of nine tumours which showed allele losses, the losses were from the wild-type chromosome. This suggests that the putative 'breast-ovarian' cancer gene is indeed a tumour suppressor gene.
TL;DR: The levels of a specific mitochondrial DNA deletion measured in 12 brain regions of 6 normal adults 39 to 82 years old exhibited striking variation among anatomical locations, suggesting that mtDNA4977 may be the “tip of the iceberg” of the spectrum of somatic mutations produced by oxidative damage.
Abstract: The levels of a specific mitochondrial DNA deletion (mtDNA4977) measured in 12 brain regions of 6 normal adults 39 to 82 years old exhibited striking variation among anatomical locations. Comparisons of the same region among individuals showed an increase of mtDNA4977 with age. The three regions with the highest levels, caudate, putamen and substantia nigra, are characterized by a high dopamine metabolism. The breakdown of dopamine by mitochondrial MAO produces H2O2 which can lead to oxygen radical formation. We suggest that mtDNA4977 may be the “tip of the iceberg” of the spectrum of somatic mutations produced by oxidative damage.
TL;DR: The found restriction site polymorphisms in the human H19 gene support the possibility of single-step inactivation of monoallelically expressed growth-regulating genes in human oncogenesis.
Abstract: Monoallelic expression of several genes has been observed in mice in which transcripts from parental homologues are distinguishable, but this phenomenon has not been demonstrated in humans. One monoallelically expressed murine gene, H19, encodes an abundant fetal RNA. We have found restriction site polymorphisms in the human H19 gene, located on chromosome 11p15, and examined the representation of these polymorphisms in cDNAs from fetal organs. Expression of H19 is largely or exclusively from a single allele; a similar analysis of the WT1 gene, on 11p13, shows biallelic expression. In the context of previous studies of 11p15 allelic losses in human embryonal tumours, our findings support the possibility of single-step inactivation of monoallelically expressed growth-regulating genes in human oncogenesis.
TL;DR: A physical map of chromosome 17p11.2–p12, which contains a submicroscopic duplication in patients with Charcot–Marie–Tooth disease type 1A is constructed and it is proposed that the de novo CMT1A duplication arises from unequal crossing over due to misalignment at these C MT1A–REP repeat sequences during meiosis.
Abstract: We have constructed a 3.1 megabase (Mb) physical map of chromosome 17p11.2-p12, which contains a submicroscopic duplication in patients with Charcot-Marie-Tooth disease type 1A (CMT1A). We find that the CMT1A duplication is a tandem repeat of 1.5 Mb of DNA. A YAC contig encompassing the CMT1A duplication and spanning the endpoints was also developed. Several low copy repeats in 17p11.2-p12 were identified including the large (> 17 kb) CMT1A-REP unit which may be part of a mosaic repeat. CMT1A-REP flanks the 1.5 Mb CMT1A monomer unit on normal chromosome 17 and is present in an additional copy on the CMT1A duplicated chromosome. We propose that the de novo CMT1A duplication arises from unequal crossing over due to misalignment at these CMT1A-REP repeat sequences during meiosis.
TL;DR: It is suggested that increased dosage of the PMP–22 gene may be the cause of CMT1A neuropathy.
Abstract: Charcot-Marie-Tooth disease (CMT1) is the most common form of inherited peripheral neuropathy. Although the disease is genetically heterogeneous, it has been demonstrated that the gene defect is the most frequent type (CMT1A) is the result of a partial duplication of band 17p11.2. Recent studies suggested that the peripheral hypomyelination syndrome in the trembler (Tr) mouse, a possible animal model for CMT1 disease, is associated with a point mutation in the peripheral myelin protein-22 gene (pmp-22). Expression of pmp-22 is particularly high in Schwann cells, and the protein is found in peripheral myelin. We now report that the human PMP-22 gene is contained within the CMT1A duplication. We therefore, suggest that increased dosage of the PMP-22 gene may be the cause of CMT1A neuropathy.
TL;DR: A point mutation in PMP–22 was found which was completely linked with the Charcot–Marie–Tooth disease type 1A, suggesting that both structural alteration and overexpression of PMP-22 may lead to the disease.
Abstract: We have investigated the peripheral myelin protein gene, PMP-22, in a family with Charcot-Marie-Tooth disease type 1A (CMT1A). The DNA duplication commonly found in CMT1A was absent in this family, but strong linkage existed between the disease and the CMT1A marker VAW409R3 on chromosome 17p11.2. We found a point mutation in PMP-22 which was completely linked with the disease. The mutation, a proline for leucine substitution in the first putative transmembrane domain, is identical to that recently found in the Trembler-J mouse. The presence of this PMP-22 defect in this CMT1A family and the location of PMP-22 within the DNA duplication associated with CMT1A suggest that both structural alteration and overexpression of PMP-22 may lead to the disease.
TL;DR: It is found that expanded (CAG)n alleles undergo alteration in length when transmitted from parent to offspring, and there was a greater rate of instability in male meiosis than in female meiosis.
Abstract: Expansion of the trinucleotide repeat (CAG)n in the first exon of the androgen receptor gene is associated with a rare motor neuron disorder, X-linked spinal and bulbar muscular atrophy. We have found that expanded (CAG)n alleles undergo alteration in length when transmitted from parent to offspring. Of 45 meioses examined, 12 (27%) demonstrated a change in CAG repeat number. Both expansions and contractions were observed, although their magnitude was small. There was a greater rate of instability in male meiosis than in female meiosis. We also found evidence for a correlation between disease severity and CAG repeat length, but other factors seem to contribute to the phenotypic variability in this disorder.
TL;DR: The localization of the ACE gene on the genetic map of chromosome 17 is reported, and an extremely polymorphic marker at the human growth hormone (hGH) locus which shows no recombination with ACE is identified which suggests that mutations at the ACE locus do not commonly contribute to the pathogenesis of hypertension.
Abstract: The angiotensin converting enzyme (ACE) is a key component of the renin angiotensin system that contributes to the regulation of blood pressure (BP). Recent demonstration of linkage between the ACE locus and elevated BP in a rat model of hypertension has further emphasized ACE as a candidate gene in human hypertension. We report the localization of the ACE gene on the genetic map of chromosome 17, and identify an extremely polymorphic marker at the human growth hormone (hGH) locus which shows no recombination with ACE. We have found no evidence to support linkage between the ACE locus and hypertension, which suggests that mutations at the ACE locus do not commonly contribute to the pathogenesis of hypertension in our test population.
TL;DR: This work examined two extended histopathologically confirmed EOAD pedigrees, AD/A and AD/B, with highly informative short tandem repeat (STR) polymorphisms and found complete linkage of the disease to a (CA)n dinucleotide repeat polymorphism at locus D14S43 in 14q24.3.
Abstract: Genetic linkage studies with chromosome 21 DNA markers and mutation analysis of the beta-amyloid protein precursor gene located in 21q21.3 have indicated that early-onset Alzheimer's disease (EOAD) is a heterogeneous disorder for which at least one other chromosomal locus exists. We examined two extended histopathologically confirmed EOAD pedigrees, AD/A and AD/B, with highly informative short tandem repeat (STR) polymorphisms and found complete linkage of the disease to a (CA)n dinucleotide repeat polymorphism at locus D14S43 in 14q24.3 (Zmax = 13.25 at theta = 0.0). Using additional chromosome 14 STR polymorphisms we were able to delineate the region containing the EOAD gene to an area of, at most, 8.9 centiMorgans between D14S42 and D14S53, flanking D14S43 on both sides.
TL;DR: The generated monoclonal antibodies to CFTR demonstrate that the biosynthetic arrest and intracellular retention of ΔF508 GFTR initially observed in vitro does occur in vivo and emphasizes the need to focus efforts on understanding the mislocalization.
Abstract: Misprocessing and mislocalization of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) has been described for the major CF–causing mutation (ΔF508) in heterologous expression systems in vitro. We have generated monoclonal antibodies (mAbs) to CFTR with the aim of localizing the protein and its CF variants in vivo. Of the tissues where CFTR was observed, only the sweat gland is readily available and does not undergo secondary changes due to CF disease pathology. Sweat ducts from CF patients homozygous for ΔF508 did not show the typical apical membrane staining seen in control biopsies. This demonstrates that the biosynthetic arrest and intracellular retention of ΔF508 GFTR initially observed in vitro does occur in vivo and emphasizes the need to focus efforts on understanding the mislocalization.
TL;DR: The result is the identification of about 1,200 of the estimated 15,000 genes of C. elegans, providing a more accurate estimate of the total number of genes in the organism than has hitherto been available.
Abstract: As an adjunct to the genomic sequencing of Caenorhabditis elegans, we have investigated a representative cDNA library of 1,517 clones A single sequence read has been obtained from the 5' end of each clone, allowing its characterization with respect to the public databases, and the clones are being localized on the genome map The result is the identification of about 1,200 of the estimated 15,000 genes of C elegans More than 30% of the inferred protein sequences have significant similarity to existing sequences in the databases, providing a route towards in vivo analysis of known genes in the nematode These clones also provide material for assessing the accuracy of predicted exons and splicing patterns and will lead to a more accurate estimate of the total number of genes in the organism than has hitherto been available