Dominant or Recessive

Freckles: FF, Ff = Has freckles; ff = No freckles

Attached earlobes: AA, Aa = Attached earlobes; aa = Free earlobes

Cystic fibrosis: CC, Cc = No cystic fibrosis; cc = Has cystic fibrosis

Widow's peak: WW, Ww = Widow's peak; ww = Straight hairline

Red hair: RR, Rr = Not red hair; rr = Red hair

Hitchhiker's thumb: HH, Hh = Hitchhiker's thumb; hh = Straight thumb

Albinism: AA, Aa = Normal pigmentation; aa = Albinism

Blue eyes: BB, Bb = Brown eyes; bb = Blue eyes

Huntington's disease: HH = Has disease; Hh = Has disease; hh = No disease

Sickle cell anemia: AA, AS = No sickle cell; SS = Has sickle cell (Note: AS is often considered a carrier with some resistance to malaria)