D) A? (In Other Words AA Or Aa)

Below is a pedigree for an inherited lung disease. Provide the genotypes of each of the individuals marked with lower case letters.

a) aa b) Aa c) Aa d) A? (in other words AA or Aa)

Below is a pedigree for an inherited LUNG disease. Provide the genotypes of each of the individuals marked with lower case letters.

a) Aa b) Aa c) aa d) aa e) A? (in other words AA or Aa)

1 Below is a pedigree for an inherited heart disease. What is the probability that their child F would have the inherited heart disease?

ANSWER: 50%

The adjacent pedigree is of a family with haemophilia as shown in Fig.9.4 . If the gene for haemophilia is represented by Xh and the normal allele by X', write the genotypes of each individual in the pedigree. If the genotype cannot be determined with certainty write the possible alternatives.

Answer: Begin with affected individual, III:3 . His genotypes is Xh Y. Similarly, his affected uncle II: 5 must have the same genotor.Because of the family history, his mother II:3 is an obligate carrier with genotype Xh X'. His father (II:4) must be X' Y. II:1 – X'Y (unaffected); II:2 and II:6 are X' X' III:1 - X'Y (unaffected); III:2 - X' X' ; III:4 – could be either X' X' or Xh X' (carrier) III:5 - X'Y (unaffected); III:6 - Xh X' (obligate carrier because her father is affected)

2 Explain, giving reasons, whether the following pedigrees are compatible with autosomal dominant, autosomal recessive or X-linked dominant and X-linked recessive inheritance. (Note that a pedigree may be compatible with more than one type of inheritance.)

Answers:

a. This pedigree shows dominant inheritance because of linear transmission from parent to offspring. It could be either autosomal dominant or X-linked dominant b. This is very similar to the above - autosomal dominant or X-linked dominant inheritance c. This pedigree is consistent with X-linked recessive inheritance because: i. only males are affected, ii. transmission is always through a carrier female, and there is no male to male transmission Another possibility is autosomal dominant inheritance with decrased penetrance, thus appearing to skip generations.

Examine the pedigree from a family with a genetic disease and answer the questions below:

3 a. Does this pedigree indicate autosomal dominant, recessive or sex-linked type of inheritance? Give reasons for your choice. Answer: This pedigree is consistent with autosomal dominnat inheritance with reduced penetrance. X-linked inheritance is excluded because of male to male transmission (II:1 to III:1). b. Assuming that B and b are the normal and mutant alleles respectively, what would be the genotypes of the individuals: II.1, II.2 and III.3 ?

Answer: II:1 – Bb . This individual, athough unaffected by the diease is obviously transmitting the disease II:2 – bb . This individual is normal and unrelated to the affected family III:3 – Bb. Affected individual. c. Individual II.3 requested genetic counselling. What is the probability that her child would be affected. Explain why.

Answer: II:3 is obviously transmitting the disease although she is unaffected. The chance that her children would be heterozygotes is 50%. However, only some of these would be affected, depending on the penetrance. In the aggbove pedigree, three out of five heterozygotes were affected, equal to 60%. This is only a rough measure of the penetrance because of the small number of individuals involved. Thus II:3 has a risk of 60% of 50% (=30%) that her offspring would be affected, and 20% risk that her normal offspring are in fact carriers of the abnormal gene.

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https://www.msu.edu/course/zol/344/Elsea/Pedigrees/