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Young: Medical Genetics

Multiple choice quiz

Instructions

Choose your answers from a-d by clicking the radio button next to each choice and then press 'Submit' to get your score.

Question 1

Neurofibromatosis type 1 is one of the most common autosomal dominant disorders. A woman with neurofibromatosis type 1 has an unaffected partner. Which of the following is correct regarding their children?

Question 2

Retinoblastoma usually occurs as a sporadic event but in around 10% of cases there is a positive family history due to autosomal dominant inheritance. In these families the penetrance is approximately 80% (= 0.8). A woman with retinoblastoma, whose father and grandfather were also affected, has an unaffected partner with no relevant family history. Which of the following is correct regarding their children?

Question 3

Achondroplasia shows autosomal dominant inheritance with complete penetrance. A man with achondroplasia has an unaffected partner of normal height. Their first two children are not affected. Which of the following is correct?

Question 4

Tay-Sachs disease shows autosomal recessive inheritance. Parents of a newly diagnosed affected child are referred for genetic counseling. It would be correct to tell them that:

Question 5

Phenylketonuria shows autosomal recessive inheritance with an incidence of 1 in 10 000. Assume that the population is in Hardy-Weinberg equilibrium. Which of the following is correct?

Question 6

A young man with phenylketonuria, who was successfully treated following diagnosis on newborn screening, is planning to start a family with his healthy, unaffected, and unrelated partner, who has no family history of phenylketonuria . Phenylketonuria shows autosomal recessive inheritance with an incidence of 1 in 10 000. Assume that the population is in Hardy-Weinberg equilibrium. Which of the following is correct?

Question 7

Cystic fibrosis shows autosomal recessive inheritance with an incidence of 1 in 2500. The unaffected brother of an affected girl is referred for genetic counseling. Assume that the population is in Hardy-Weinberg equilibrium. Which of the following is correct?

Question 8

Hunter syndrome is a rare form of mucopolysacchararidosis that differs from all other forms in that it shows X-linked recessive inheritance. A woman with two affected brothers is referred for genetic counseling. Which of the following is correct?

Question 9

Haemophilia A is a severe coagulation disorder that shows X-linked recessive inheritance. Red-green colour blindness also shows X-linked recessive inheritance. A man with both haemophilia A and colour blindness is referred for genetic counseling. Assume that his partner is not a carrier of either of these conditions. Which of the following is correct?

Question 10

A woman who has two brothers and a maternal uncle (her mother's brother) with non-specific X-linked mental retardation is referred for genetic counseling. There are no diagnostic tests available to help determine whether or not she is a carrier. Which of the following is correct?

Question 11

Pedigree

In this pedigree A and B represent alleles at a marker locus closely linked to the disease locus. Affected individuals are shown as shaded. The disease status in III 1 is unknown. Which of the following is correct?

Question 12

Pedigree

In this pedigree II 1 is affected with an autosomal recessive disorder. The disease status for II 2 and II 3 is unknown. A and B represent alleles at a locus which is tightly linked to the disease locus with recombination fraction of 0. On the basis of the linked marker genotypes II 2 can be told that:

Question 13

Pedigree

On the basis of the linked marker genotypes II 3 can be told that:

Question 14

Pedigree

In this pedigree II 1 is affected with an autosomal recessive disorder. The disease status for II 2, II 3 and II 4 is unknown. A and B represent alleles at a locus which is tightly linked to the disease locus with recombination fraction of 0. On the basis of the linked markers II 2 can be told that:

Question 15

In the pedigree shown in Question 14, on the basis of the linked marker results II 3 can be told that:

Question 16

In the pedigree shown in question 14, on the basis of the linked marker results II 4 can be told that:

Question 17

Pedigree

In this pedigree II 1 is affected with an autosomal recessive disorder. The disease status for II 2 is unknown. A and B represent alleles at a locus which is tightly linked to the disease locus with recombination fraction of 0. Using the linked markers, II2 can be told that:

Question 18

Pedigree

In this pedigree II 3 and III 1 are affected with an X-linked recessive disorder which is tightly linked to a marker locus with alleles A and B, with a recombination fraction of 0 between the disease and marker loci.
Analysis of the linked marker results indicates that the disease must be segregating with:

Question 19

Pedigree

The marker genotype for I 2 must have been:

Question 20

Pedigree

Using the linked markers III 3 can be told that:

Question 21

Pedigree

In this pedigree I 1 and II 2 have Becker muscular dystrophy which shows X-linked recessive inheritance. III 2 has oculocutaneous albinism which shows autosomal recessive inheritance with an incidence in the general population of 1 in 10 000. The disease status for both Becker muscular dystrophy and oculocutaneous albinism is unknown for IV 1 and IV 2.
What is the probability that III 3 is a carrier of Becker muscular dystrophy?

Question 22

Pedigree

What is the probability that III 3 is a carrier of oculocutaneous albinism?

Question 23

Pedigree

What is the probability that IV 1 is a carrier of oculocutaneous albinism?

Question 24

Pedigree

What is the probability that IV 2 will be affected with Becker muscular dystrophy?

Question 25

Pedigree

What is the probability that IV 2 will be affected with oculocutaneous albinism?