1. s

2. Today...
Analyze pedigrees to determine the mode of inheritance of a specific trait
Determine the chance of offspring having a specific trait based off pedigree analysis
In humans, pedigree analysis is an important tool for studying inherited diseases
figure out the genetic basis of a disease or trait from its inheritance pattern
predict the risk of disease in future offspring in a family (genetic counseling)

3. Today... Pedigree analysis
Basic patterns of inheritance
autosomal, recessive
autosomal, dominant
X-linked, recessive
X-linked, dominant (very rare)
Y-Linked
Mitochondrial inheritance
X-rec. X-dom. Mitochondrial and Y-linked (sex-linked traits)

5. Autosomal recessive traits
Trait is rare in pedigree
Trait often skips generations (hidden in heterozygous carriers)
Heterozygous parents will have about ¼ of kids affected
Trait affects males and females equally
Usually, affected kids have normal parents
If both parents are affected—all kids will be

6. Autosomal recessive diseases in humans
Most common ones
Cystic fibrosis
Sickle cell anemia
Phenylketonuria (PKU)
Tay-Sachs disease
For each of these, overdominance (heterozygote superiority) has been suggested as a factor in maintaining the disease alleles at high frequency in some populations

7. Autosomal dominant pedigrees
Trait is common in the pedigree
Males and females equal
Affected offspring must have affected parents (unless mutation)
Trait is found in every generation
Affected individuals transmit the trait to ~1/2 of their children (regardless of sex)

8. Autosomal dominant traits
There are few autosomal dominant human diseases:
Achondroplasisa
Neuorfibromatosis
Huntington’s Disease

9. X-linked recessive pedigrees
Trait is rare in pedigree
Trait skips generations
Affected fathers DO NOT pass to their sons
Males are more often affected than females
Daughters of affected males are carriers (Heterozygous)
Only females will be heterozygous
Affected males usually born to unaffected females

10. X-linked recessive traits
Hemophilia
Muscular Dystrophy
Colorblindness

11. X-linked recessive traits
ex. Glucose-6-Phosphate Dehydrogenase deficiency
hemolytic disorder causes jaundice in infants and (often fatal) sensitivity to fava beans in adults
the most common enzyme disorder worldwide, especially in those of Mediterranean ancestry
may confer malaria resistance

12. X-linked dominant pedigrees
Trait is common in pedigree
Affected fathers pass to ALL of their daughters
Males and females are equally likely to be affected
Every generation
Sometimes more often in females (fatal in males)
Affected sons must have affected mother
Affected daughters must have affected mother or father

13. X-linked dominant diseases
X-linked dominant diseases are extremely unusual
Often, they are lethal (before birth) in males and only seen in females
ex. Rett
ex. X-linked rickets (bone lesions)

14. Y-linked expression
=> only found in males

15. Y-linked traits Male patterned baldness Hairy ears
Y-chromosome infertility

16. Mitochondrial Inheritance
Only ova have this type of DNA--
Mom’s will give to ALL kids
If mom is unaffected, NO kids will be

17. Mitochondrial Inheritance
Dysfunctional mitochondria
Poor growth
Loss of muscle coordination, muscle weakness, visual problems, hearing problems, learning disabilities, heart disease, liver disease, kidney disease, gastrointestinal disorders, respiratory disorders, neurological problems, autonomic dysfunction and dementia

18. What is the pattern of inheritance?
What are IV-2’s odds of being a carrier?

19. Sample pedigree - cystic fibrosis
What can we say about I-1 and I-2?
What can we say about II-4 and II-5?
What are the odds that III-5 is a carrier?

20. What is the inheritance pattern?
What is the genotype of III-1, III-2, and II-3?
What are the odds that IV-5 would have an affected son?

21. III-1 has 12 kids with an unaffected wife
8 sons - 1 affected
4 daughters - 2 affected
Does he have reason to be concerned about paternity?

23. Practice 1 2 3 4 5 6 7 8 9 10 I II
III

24. Autosomal Dominant

26. Autosomal Recessive

28. Autosomal Dominant

30. Autosomal Recessive

32. Autosomal Dominant

34. Sex Linked Recessive

36. X linked Dominant

38. Autosomal Dominant

40. Y-linked

41. Draw a Pedigree on your own…
On a sheet of paper
Isaac and Chloe have 3 kids. Omar, Sarah and Hunter: Omar and Hunter both have achondroplasisa. Sarah does not. She marries Kyle and has three kids: Phil, Rory and Beth. Rory suffers from achondroplasisa while Phil and Beth do not. Omar marries Hailey and they have 2 kids, Kameron , who has the disorder and Shawn who does not. Kameron marries Lauren, who is a dwarf and has Nathan and Jamie, neither of which are dwarfs. Hunter marries Samantha and has Joey and Bryson. Bryson is a dwarf, Joey is short, but not a dwarf. Laura marries Robert, who is a dwarf and has Mason, Covey and Erica. Mason is a dwarf and marries Julianna, who is normal size and they have Anna, normal size as well. Covy is normal sized but falls in love with his sister, Erica. They have three kids, Sean, Drew and Matt , all three of which are dwarfs. Draw a pedigree for this family, showing the name and genotype for each individual.
On a scale of 1-5, how do you feel about pedigrees today?