AGB 121: Principles of Animal Genetics and Population Genetics (2+1)

MONOSOMY

• It is a chromosomal aberration where one chromosome is lost from a pair.
• The monosomic individual has one chromosome less than the normal number of chromosomes.
• Monosomic will result when an n-1 gamete fuses with a normal gamete.
• Examples
  • Turners’ syndrome in females (45, XO)
    • Individual will be having only a single X chromosome (XO).
    • About 1 in 5000 female births show Turner syndrome.
    • Affected people have a characteristic phenotype: they are sterile females, short in stature, and often have a web of skin extending between the neck and shoulders.
    • Turner syndrome is named after Dr. Henry Turner, who in 1938 published a report describing the disorder.
  • One example of partial monosomy is found in cri-du-chat syndrome, which result from loss of part of the short arm of chromosome 5. Individuals with this syndrome suffer severe mental and physical impairment, and have a distinctive cry like that of a cat (which gives the syndrome its name).