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i) i) Write genotypesfor as many individuals in the pedigree as possible. Write

ID: 4844 • Letter: I

Question

i)        i) Write genotypesfor as many individuals in the pedigree as possible. Write eachgenotype below the corresponding symbol in the pedigree.

ii) The individuals marked 1 and 2 are planning to have a child.They know about their family history of galactosemia, so they visita genetic counselor to find out the probability that the child willhave galactosemia. What does she tell them?

iii) The couple has a son and he does not have galactosemia.They decide to have a second child and again visit the geneticcounselor. What does she tell them is the probability that thesecond child will have galactosemia? Note: for this and thenext question, it will help if you update the pedigree to includethe new child. Then determine whether you should alter any of yourinferred genotypes as a result.

iv) The couple’s second child is born, and he hasgalactosemia. They decide to have a third child and again visit thegenetic counselor. What does she tell them is the probability thatthe third child will have galactosemia?

i)        i) Write genotypesfor as many individuals in the pedigree as possible. Write eachgenotype below the corresponding symbol in the pedigree.

ii) The individuals marked 1 and 2 are planning to have a child.They know about their family history of galactosemia, so they visita genetic counselor to find out the probability that the child willhave galactosemia. What does she tell them?

iii) The couple has a son and he does not have galactosemia.They decide to have a second child and again visit the geneticcounselor. What does she tell them is the probability that thesecond child will have galactosemia? Note: for this and thenext question, it will help if you update the pedigree to includethe new child. Then determine whether you should alter any of yourinferred genotypes as a result.

iv) The couple’s second child is born, and he hasgalactosemia. They decide to have a third child and again visit thegenetic counselor. What does she tell them is the probability thatthe third child will have galactosemia?

Explanation / Answer

i)                   i) Write genotypes for as many individuals in the pedigree aspossible. Write each genotype below the corresponding symbol in thepedigree.

                                         Aa       xAa       

                             A    a         A                   a

25% percentage of having galactosemia child

ii)                  The individuals marked 1 and 2 are planning to have a child. Theyknow about their family history of galactosemia, so they visit agenetic counselor to find out the probability that the child willhave galactosemia. What does she tell them?

25% percentage of having galactosemiachild

iii)               The couple has a son and he does not have galactosemia. They decideto have a second child and again visit the genetic counselor. Whatdoes she tell them is the probability that the second child willhave galactosemia? Note: for this and the next question, itwill help if you update the pedigree to include the new child. Thendetermine whether you should alter any of your inferred genotypesas a result.

                                Risk is same as every issue is new event ofcombination

iv) The couple’s second child is born, and he hasgalactosemia. They decide to have a third child and again visit thegenetic counselor. What does she tell them is the probability thatthe third child will have galactosemia?

25% percentage of having galactosemiachild

Risk is same as every issue is new event ofcombination for third child also