DGS 3223 Chapter Notes - Chapter 6: Isochromosome, Cytogenetics, Allosome
8 Sep 2016
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Avery welch medical cytogenetics prelim 1 chapter 6 basic cytogenetic nomenclature: inv = inversion. Break in a chromosome and the piece flips 180 degrees and rejoins. Note lack of punctuation within parentheses: del = deletion. List breakpoint nearest the centromere first (proximal) before the more distal breakpoint. Breakpoints define the segment deleted: i = isochromosome. 2 of the same arms; 2 long or 2 short, missing the other (ie 2 long with no short) The q10 breakpoint indicates that it is the long arm that is present, and implies that no short arm is present. Involvement of 2 chromosomes: the lowest numbered chromosome is listed first, unless a sex chromosome is involved, in which case it is listed first. If there is a sex chromosome abnormality, only the normal sex chromosome is. Listed, then a comma, then the sex chromosome abnormality: if an x and a y chromosome are involved, the x chromosome is always listed first.
