Genome Mapping Professor Simon G. Gregory

Genome MappingProfessor Simon G. GregoryWhy study chromosomal aberrations?• Chromosomal rearrangements are implicated in many disorderssuch as Infertility, Mental Retardation, Autism, Schizophrenia, Cancer– Cancer• The identification and characterization of theseabnormalities are important for understanding the pathogenesisof cancer• Selection of optimal targets for cancer therapyon an individual level• Clinical applications– Multiple congenital abnormalities– Mental retardation (mild to profound) of unknown origin or associatedwith minor or major malformations– Multiple unexplained spontaneous abortions– Family history of Down syndrome or other chromosome abnormality– Ultrasound abnormalities during pregnancy4Cytogenetic mapping (2)• The treatment of chromosomes arrested at metaphase and digestionwith trypsin and Giemsa stained creates differential chromosome bandingpatterns and the generation of light (R-bands) and dark (G-bands)• Giemsa staining is reliant upon nucleotide content and the staining patterntherefore reflects the base composition and correlates other propertiesof the different regionsG-bandsDark stainingGiemsa bandsAT richLate replicatingEarly condensationSINE poor, LINE richGene poorLess frequentrecombinationR-bandsLight StainingGiemsa bandsGC richEarly replicatingLate condensationSINE rich, LINE poorGene richMore frequentrecombination5Basic chromosome structure1. SizeScientists use three keyfeatures to identifychromosomes2. Bandingpattern3. Centromerepositionshortarmsatellitecentromeretelomere/subtelomereChromosome 1MetacentricChromosome 4Submetacentriclong armChromosome 14Acrocentric6The screen versions of these slides have full details of copyright and acknowledgements2