Module 1 Terms

Autosomal Recessive

• appears in both sexes

• tends to skip generations

• affected offspring born to unaffected parents

• heterozygous parents = ¼ offspring affected

Autosomal Dominant

• appears in both sexes

• doesn’t skip generations

• both sexes transmit the trait to offspring

• affected offspring born to affected parent

• affected + unaffected parent = ½ offspring affected

X-Linked Recessive

• appears in more males

• skips generations

• affected sons born to unaffected mothers

• heterozygous mother = ½ sons affected

• all daughters of affected fathers are carriers

X-Linked Dominant

• appears in more females

• doesn’t skip generations

• affected son born to affected mother

• affected daughter born to affected mom/dad

• affected father pass trait to all daughters

• affected mother = ½ to sons, ½ to daughters

Y-Linked

• only males affected

• passed from father to all sons

• doesn’t skip generations

Type A

IᴬIᴬ
Iᴬi

Type B

IᴮIᴮ
Iᴮi

Type AB

IᴬIᴮ

Type O

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