1. The trait is autosomal recessive.
2. Individual II-2 is affected, so she must be homozygous recessive (aa).
3. Individual I-1 is unaffected and must be a carrier (Aa) because he has an affected daughter (II-2).
4. Individual I-2 is affected (aa), so she is homozygous recessive.
5. Individual II-1 is unaffected, so he could be AA or Aa. Since his mother (I-2) is aa, he must be Aa.
6. Individual II-3 is unaffected and has an affected parent (I-2), so he must be Aa.
7. Individual II-4 is affected, so he is aa.
8. Individual II-5 is unaffected and has an affected parent (I-2), so he is Aa.
9. Individual III-1 is unaffected, so he could be AA or Aa.
10. Individual III-2 is unaffected and has an affected father (II-4, aa), so she must be Aa.
11. Individual III-3 is unaffected and has an affected father (II-4, aa), so he must be Aa.
12. Individual III-4 is affected, so he is aa.
13. Individual III-5 is affected, so he is aa.
14. Individual III-6 is affected, so she is aa.
15. The pedigree shows a pattern consistent with an autosomal recessive disorder.
Parent Tip: Review the logic above to help your child master the concept of pedigree practice worksheet.
