Codominance: Alpha-1 Antitrypsin Deficiency

Only dominant alleles are present.

Codominance facts:

  • occurs when two alleles are both dominant phenotypes
  • results in both genes being expressed
  • co= together, so the  dominant traits appear together in the hybrid organism's phenotype
  • one trait doesn't dominate another both traits just appear
  • this doesn't disprove Mendel's original theory, but rather expands off it
  • example: blood type AB- both proteins of A and B appear in blood

Alpha-1 Antitrypsin Deficiency Facts:

  • most commonly caused by having two copies of the M(dominant) -allele in SERPINA1
  • body doesnt make enough protein to protect the lungs and liver
  • a long term effect is liver and lung disease
  • affects about 1 in 1500 to 3000 worldwide with European ancestry
  • it is uncommon in the Asian gene line