Please enable JavaScript.

Coggle requires JavaScript to display documents.

MM14 - genetics 2, cytogenetics, human chromosomes + chromosomal disorders…

- - - - can occur in meiosis 1 or 2 with different consequences...
        
        1: gametes either have both parental chromos or none (should have 1)
        
        2: gametes either contain 2 identical chromatids or none (should have 1)
    - - consisting of cells of 2 genetically different types
      - usually not severe
      - we are all a bit mosaic (usually not enough for a phenotype)
    - - Down's Syndrome (trisomy 21)
        
        1 in 650 live births
        
        50% miscarry
        
        increased risk with maternal age
        
        less reliable dysjunction
        
        age 30: 1 in 900
        
        age 44: 1 in 40
        
        47, XX/XY, +21
      - Edward's Syndrome (trisomy 18)
        
        rocker-button feet, death usually in 1st year)
      - Patau Syndrome (trisomy 13)
        
        polydactyly, death usually in 1st year
      - Turner syndrome (X monosomy)
        
        short stature, lowset eyes
      - Kleinefelter syndrome
        
        trisomy of X - XXY
      - Triple X syndrome
        
        trisomy of X - XXX
  - - - duplication, deletion, inversion
      - ring chromo (telomeres absent, ends fuse, learning disability)
    - - reciprocal: exchange between non-homologs
      - robertsonian: break @ centremeres + P arms of 2 chromos fuse