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10.6 Population & Clinical Genetics of Human Disease ā Test 3
Q1. An autosomal recessive disease affects 1 in 2,500 people. Under Hardy-Weinberg equilibrium, the approximate carrier (heterozygote) frequency is:ā 1 in 25
Q2. Duchenne muscular dystrophy (X-linked recessive) affects about 1 in 3,500 boys. The approximate carrier frequency in females is:ā 1 in 1,750
Q3. If sickle-cell disease occurs in about 1 in 400 African-Americans, the approximate carrier (sickle-trait) frequency is:ā 1 in 10
Q4. A woman affected by an X-linked dominant disorder (heterozygous) has children with an unaffected man. The expected affected offspring are:ā 1/2 of sons and 1/2 of daughters
Q5. In a disease where each child has a 1/4 chance of being affected, the probability that exactly one of two children is affected is:ā 3/8
Q6. In multifactorial (threshold) inheritance, recurrence risk in a family is higher when the affected proband is:ā Of the less commonly affected sex
Q7. A non-smoking adult with early emphysema and a family history most likely has a deficiency of:ā Alpha-1-antitrypsin (autosomal recessive)
Q8. Population genetic screening for Huntington disease does not meet standard screening principles mainly because:ā The condition cannot currently be effectively prevented or treated
Q9. A major barrier to population-wide cystic fibrosis carrier screening has been that:ā There are many different CFTR mutations
Q10. Consanguineous (related) matings increase offspring risk for recessive disease because they raise the:ā Inbreeding coefficient (chance of homozygosity by descent)
Q11. The persistence of the sickle-cell allele at high frequency in malarial regions is explained by:ā Heterozygote advantage (balancing selection)
Q12. In the Hardy-Weinberg expansion pĀ² + 2pq + qĀ², the heterozygous carriers are represented by:ā 2pq
Q13. When both parents are unaffected carriers of an autosomal recessive disease, the recurrence risk for each child is:ā 1/4
Q14. Recurrence risks for multifactorial disorders are usually obtained from:ā Empirical (observed) family data
Q15. In a small, isolated population descended from few founders, a particular genetic disease may be unusually common due to the:ā Founder effect
Q16. Newborn screening (e.g. for PKU) is justified mainly because the condition is:ā Detectable early and treatable to prevent harm
Q17. The purpose of heterozygote (carrier) testing in populations such as Tay-Sachs screening is to:ā Identify carriers for reproductive counselling
Q18. Genetic testing for familial adenomatous polyposis is valuable because identifying carriers allows:ā Surveillance and preventive surgery to reduce cancer risk
Q19. Prenatal diagnosis of chromosomal abnormalities is commonly performed using:ā Amniocentesis or chorionic villus sampling (CVS)
Q20. Match each term with its description and select the correct option.ā A-ii, B-i, C-iv, D-iii