Patterns of inheritance

Question 1

Autosomal Dominant

Answer 1

• Individuals affected in every generations
• Does not skip generations
• Appear equally in males and females
• Affected people have at least one affected parent
• Some carriers may not manifest disease
• Males and females have equal chance of passing on mutation
• 50% risk to children

Question 2

Autosomal Recessive

Answer 2

• May be only one generation affected
• Carriers typically do not have condition
• Both parents must be carriers of the mutation
• 25% risk to children
• Usually appear equally in males and females
• Tends to skip generations

Question 3

X-linked Recessive

Answer 3

• More males are affected than females
• Affected sons are usually born to unaffected mothers; thus, the trait skips generations
• Approximately half of a carrier (heterozygous) mother’s sons are affected
• Never passed from father to son
• All daughters of affected fathers are carriers

Question 4

X-linked Dominant

Answer 4

• Both males and females are usually affected. More females than males are affected
• Does not skip generations. Affected sons have affected mother. Affected daughters have affected father or mother
• Affected fathers pass the trait to all their daughters
• Affected mothers (if heterozygous) pass the trait to half of their sons and half of their daughters

Question 5

Y linked

Answer 5

• Only males are affected
• Passed from father to all sons
• Does not skip generations