Towards a transcription map of human chromosome 21: Identification of expressed sequences by exon trapping
- Geneva Univ. Medical School (Switzerland); and others
Chromosome 21q contains about 1% of the human genome, and when triplicated is responsible for Down syndrome. The genetic and physical maps of this chromosome are amongst the most developed of all human chromosomes. A considerable international effort is now under way with the aims of cloning and mapping all chromosome 21 genes, assigning functions, and determining their involvement in disease phenotypes. We have used exon trapping/amplification methods to identify exons of genes that map on chromosome 21. EcoR1 or Bam HI-digested DNA from pools of 96 cosmids from the chromosome 21 library LL21NC02{open_quotes}Q{close_quotes} were used for cloning in vector pSLP3 (after elimination of cosmids positive for ribosomal RNR genes and mouse DNA); recombinant plasmids were transfected into cos7 cells and trapped sequences were subcloned. False positive clones, i.e. those containing vector self-spliced sequences (which represented between 8-30% of clones in different experiments), have been eliminated by hybridization of oligonucleotides corresponding to sequences of the vector self-spliced events. More than 100 different trapped {open_quotes}exons{close_quotes} have been identified to date after single or double pass sequencing. Two sequences matched exons of known genes on chromosome 21 (COL6A 1 and MX1). About 45% of the sequences were entirely new, i.e. there was no homology with entries in the nucleotide or protein databases (blastin and blastx searches). An additional 48% of the sequences were homologous but not identical to sequences in the databases. Only 4% were repetitive elements. Specific homologies will be presented. All of the trapped sequences that have been mapped by filter hybridization, PCR, or FISH, map back to cosmids or YACs of chromosome 21. This approach permits rapid identification of expressed sequences of this chromosome, the cloning of its genes, and the understanding of its disorders.
- OSTI ID:
- 134390
- Report Number(s):
- CONF-941009--
- Journal Information:
- American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BASIC STUDIES
99 GENERAL AND MISCELLANEOUS
CHROMOSOMAL ABERRATIONS
CONTIGS
DATA BASE MANAGEMENT
DNA HYBRIDIZATION
DNA SEQUENCING
DNA-CLONING
DOWNS SYNDROME
EXONS
FLUORESCENCE
GENES
GENETIC MAPPING
HEREDITARY DISEASES
HUMAN CHROMOSOME 21
OLIGONUCLEOTIDES
PATIENTS
PHENOTYPE
POLYMERASE CHAIN REACTION
SPLICING
STRUCTURE-ACTIVITY RELATIONSHIPS
TRANSCRIPTION
YEASTS