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Question 9. If two loci show genetic linkage then:

a) they can be on two different non-homologous chromosomes.
True False

b) genes in coupling at these loci are inherited together more often than would be expected by chance.
True False

c) the likelihood of a recombination event occurring between them is greater in males than in females.
True False

d) alleles at these loci will always show linkage disequilibrium.
True False

e) if the recombination fraction ([thetas]) between them equals 0.01, this means that genes in repulsion at these loci will be brought together during on average 10% of meioses.
True False

Question 10. Indicate which of the following statements are true.

a) The symbol in a pedigree for a male individual is a square.
True False

b) A male child born to a man with an X-linked disorder has to inherit the disorder from his father.
True False

c) Advanced paternal age is associated with an increased risk of a child having an autosomal dominant disorder due to a new mutation.
True False

d) Reduced penetrance and variable expressivity are typical features of autosomal recessive disorders.
True False

e) Pseudodominance explains reduced penetrance of dominant disorders.
True False

Question 11. In multifactorial inheritance:

a) boys are affected more often than girls.
True False

b) recurrence risks are influenced by the number of affected close relatives.
True False

c) if boys are affected by a particular condition more often than girls, then the recurrence risk is greater for the sons of affected boys than for the sons of affected girls.
True False

d) most of the genes which cause common malformations such as cleft lip/palate and spina bifida have been identified.
True False

e) recurrence risks can be obtained from family studies or by calculation from basic principles.
True False

Question 12. Question-The following statements are TRUE or FALSE ? A major malformation

a) can be caused by single-gene inheritance.
True False

b) is present in 10% of all newborn infants.
True False

c) is present in all babies with Down's syndrome.
True False

d) is caused by a non-disruptive mechanical force.
True False

e) is always obvious at birth.
True False

Question 13. Known teratogenic agents include:

a) alcohol.
True False

b) hypothermia.
True False

c) maternal phenylketonuria.
True False

d) cytomegalovirus.
True False

e) gestational diabetes.
True False

Question 14. Neural tube defects:

a) are best classified as disruptions.
True False

b) usually show multifactorial inheritance.
True False

c) can be caused by a teratogen.
True False

d) can be prevented by folic acid periconceptional supplementation.
True False

e) can be diagnosed during pregnancy by specific DNA mutation analysis.
True False

Question 15. Indicate which of the following statements are true.

a) Adult haemoglobin consists of two alpha globin chains and two gamma globin chains.
True False

b) Sickle cell disease is due to a triplet repeat mutation.
True False

c) In alpha thalasseamia there is normal production of the alpha globin chains of haemoglobin.
True False

d) Thalassaemia minor is a less severe form of beta thalassaemia.
True False

e) Hb C is a disorder of haemoglobin structure.
True False

Question 16. Indicate which of the following statements are true.

a) An unaffected sibling of an individual with an autosomal recessive disorder has a one in two chance of being a carrier.
True False

b) Anticipation is commonly seen with autosomal recessive disorders.
True False

c)Daughters of a male with an X-linked disorder are obligate carriers.
True False

d) Children born to a female with a mitochondrial disorder are at risk of inheriting the disorder.
True False

e) A first cousin of a person with cystic fibrosis has a 1 in 8 chance of being a carrier.
True False

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