Pedigree Patterns of Inheritance

Question 1

Autosomal Dominant

Answer 1

-Appears in both sexes with equal frequency
-Both sexes transmit the trait to their offspring
-DOES NOT SKIP GENERATIONS
-Affected offspring must have an affected parent unless they possess a new mutation
-When one parent is affected (het.) and the other parent is unaffected, approx 1/2 of the offspring will be affected
-Unaffected parents do not transmit the trait

Question 2

Autosomal Recessive

Answer 2

-Appears in both sexes with equal frequency
-TRAIT TENDS TO SKIP GENERATIONS
-Affected offspring are usually born to unaffected parents
-When both parents are heterozygous, approx 1/4 of the progeny will be affected

Question 3

X-Linked Recessive

Answer 3

-More males than females are affected
-Affected sons are usually born to unaffected mothers, THUS THE TRAIT SKIPS GENERATIONS
-Approximately 1/2 of carrier mothers’ sons are affected
-IT IS 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 affected; often more females than males are affected
-DOES NOT SKIP GENERATIONS
-Affected sons must have an affected mother; affected daughters must have an affected mother or an affected father
-Affected fathers will pass the trait on to all their daughters
-Affected mothers if heterozygous will pass the trait on to 1/2 of their sons and 1/2 of their daughters

Question 5

Y-Linked

Answer 5

-ONLY MALES AFFECTED
-It is passed from father to all sons and does not skip generations