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

EFFECTS OF DEFICIENCY OR DELETION

• Chromosomes with a deletion cannot be reverted back to wild type conditions.
  • If the deleted portion is without a centromere, the individual will not survive.
  • When deletion chromosomal gamete unites with another normal gamete a zygote is produced that carries a particular group of genes in a single dose.
  • Expression of single recessive trait with a single dose of recessive gene in the absence of a deficiency/deletion is called pseudo-dominance.

• Deficiencies have deleterious effects in the organisms.
  • For example, a deletion of a portion of long arm of chromosome 21 leads to chronic myeloid leukemia in human beings.
  • Similarly, a loss of the short arm of chromosome 5 results in Cri-Du-Chat syndrome (cry of cat syndrome).