Lecture 40 Prof Duncan Shaw.

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Presentation transcript:

Lecture 40 Prof Duncan Shaw

Chromosome abnormalities Numerical abnormalities - gain or loss of one or more whole chromosome(s) Includes aneuploidy (trisomy, monosomy) Structural abnormalities - chromosome breakage and rejoining in a different configuration Includes translocations, deletions, inversions Only a few are compatible with life

Aneuploidies

The cause of aneuploidy Non-disjunction - failure of pairs of chromosomes to separate during meiosis I or II Probably usually due to ageing of oocyte, hence maternal age effect Environmental factors may also be important, e.g. radiation

Structural abnormalities Translocation - transfer of part of one chromosome to another Reciprocal translocation Robertsonian translocation Deletions - loss of material from within a chromosome (usually lethal) Insertions - extra material added within a chromosome Inversion - section within a chromosome is turned around