Quiz 4: Single gene disorders

Please choose the one, most correct answer to each question or statement.

1. Oculocutaneous albinism, Waardenburg syndrome and haemophilia are inherited as:
   • Single gene defects.
   • Multifactorial disorders.
   • Congenital disorders due to a teratogen.
   • Trisomies.
2. Waardenburg syndrome is inherited as:
   • An autosomal dominant disorder.
   • An autosomal recessive disorder.
   • An X-linked recessive disorder.
   • A chromosomal abnormality.
3. What is an important feature of Waardenburg syndrome?
   • Very blue eyes.
   • Pale skin.
   • Intellectual disability.
   • Slow growth.
4. The main complication of Waardenburg syndrome is:
   • Severe sun damage.
   • Convulsions.
   • Severe deafness.
   • Blindness.
5. The risk of a child having Waardenburg syndrome if one of the parents is affected is:
   • Very small.
   • 25%.
   • 50%.
   • 100%.
6. How is oculocutaneous albinism inherited?
   • As an autosomal dominant disorder.
   • As an autosomal recessive disorder.
   • As an X-linked recessive disorder.
   • As a chromosomal abnormality.
7. How common is oculocutaneous albinism in the black population of South Africa?
   • About 1 per 1000 live births.
   • About 1 per 4000 live births.
   • About 1 per 10 000 live births.
   • About 1 per 50 000 live births.
8. What are the main features of oculocutaneous albinism?
   • Light-coloured eyes only.
   • Pale skin.
   • Both pale skin and light eyes.
   • Pale skin and hair with light eyes.
9. People with oculocutaneous albinism have serious problems with:
   • Hearing.
   • Vision.
   • Hearing and speech.
   • Hearing, speech and vision.
10. What is a major complication of oculocutaneous albinism?
    • Skin cancer.
    • Leukaemia.
    • Cancer of the eye.
    • Cancer of the liver.
11. Patients with oculocutaneous albinism often are:
    • Intellectually disabled.
    • Visually disabled.
    • Crippled due to joint damage.
    • Socially isolated.
12. Important care in patients with oculocutaneous albinism includes:
    • Sun protection at all times.
    • Prophylactic antibiotics.
    • Special diet high in protein.
    • A hearing aid.
13. What is the cause of haemophilia?
    • Too few platelets in the blood.
    • Lack of normal blood clotting factors VIII or IX.
    • Too few red cells in the blood.
    • Lack of vitamin K.
14. Haemophilia is inherited as:
    • An autosomal dominant disorder.
    • An autosomal recessive disorder.
    • An X-linked recessive disorder.
    • A chromosomal abnormality.
15. Mild haemophilia is seen:
    • Only in boys.
    • Only in girls.
    • Mostly in boys.
    • Mostly in girls.
16. What blood test can be used to screen for moderate or severe haemophilia?
    • The international Normalised Ratio (INR).
    • The partial thromboplastin time (PTT).
    • A platelet count.
    • The haemoglobin concentration.
17. What is a common complication of severe haemophilia?
    • Haemarthroses (bleeds into joints).
    • Intracranial haemorrhages.
    • Blood in the stool.
    • Vomiting blood.
18. What is the management of a child with haemophilia who presents with a haematoma (bleed into a muscle)?
    • Reassure the mother that it will recover over the next week.
    • Place ice over the site of the bleed and give the child two aspirin.
    • Start a blood transfusion.
    • Start a transfusion of factor VIII or IX.
19. What is the risk for parents who have 2 sons with haemophilia having another affected child in future pregnancies?
    • Very small.
    • 10% if a boy.
    • 50% if a boy.
    • All their future children are likely to be affected.
20. If the father has haemophilia, what is the risk of his sons having haemophilia also?
    • Nil.
    • 1:4.
    • 1:2.
    • 1:1 (100%).