1. 1. Tay Sachs Disease is a recessive genetic disorder that destroys nerve cells in the brain. This results in slowing of development and can lead to death, often around the age of four.

T = normal

t = Tay Sachs Disease

If a parent who is a carrier (heterozygous) for the disease has a child with a parent who is homozygous dominant for "normal", what are the odds the child will have Tay Sach's?

2. 2. Huntington's Disease is caused by a dominant allele. This disease impacts a person's functional abilities, movement, and personality.

H = Huntington's Disease

h = normal

If a parent who is homozygous dominant for Huntington's disease has a child with a parent who is homozygous recessive for "normal", what are the odds the child will have Huntington's diesease?

Phenylketonuria (fen-ul-key-toe-NU-ree-uh), also called PKU, is a rare disorder that causes an amino acid to build up in the body. PKU is a recessive disorder.

R = normal

r = PKU disorder

If two parents who are carriers (heterozygous) for PKU have a child, what are the chances the child will also be a carrier?

Cystic fibrosis is caused by a recessive allele.

F = normal

f = cystic fibrosis

If a carrier (heterozygous) parent has a child with a parent who has cystic fibrosis, what are the chances their child will have the disease?