Autosomal dominant or recessive?

Question 1

In autosomal dominant conditions, both homozygotes and heterozygotes manifest disease. TRUE/FALSE?

Answer 1

TRUE (there is no carrier state)

Question 2

What gender is most commonly affected in autosomal dominant conditions?

Answer 2

both males and females affected

Question 3

In autosomal dominant conditions, only affected individuals can pass on disease. TRUE/FALSE?

Answer 3

TRUE

Question 4

If a patient affected by a autosomal dominant conditions decides to have children, what percentage of their children will be affected by the disease?

Answer 4

disease is passed on to 50% of children

Question 5

Autosomal dominant conditions normally appear in every generation. TRUE/FALSE?

Answer 5

TRUE

Question 6

Describe the concept of non-penetrance

Answer 6

lack of clinical signs and symptoms (normal phenotype) despite abnormal gene.
E.g. 40% otosclerosis

Question 7

What is it called when a new mutation occurs in a child whose parents are not affected by an autosomal dominant condition?

Answer 7

sporadic mutation (e.g. common in achondroplasia ~70% sporadic mutations)

Question 8

Describe the general “rule” when trying to determine if a condition is likely autosomal dominant or recessive?

Answer 8

Autosomal recessive = ‘metabolic’
Autosomal dominant = ‘structural’

Notable exceptions:
- metabolic conditions “hyperlipidaemia type II” and “hypokalaemic periodic paralysis” are autosomal dominant
- ‘structural’ conditions such as “ataxia telangiectasia” and “Friedreich’s ataxia” are autosomal recessive

Question 9

Achondroplasia

Answer 9

Autosomal dominant

Question 10

Acute intermittent porphyria

Answer 10

Autosomal dominant

Question 11

Adult polycystic disease

Answer 11

Autosomal dominant

Question 12

Antithrombin III deficiency

Answer 12

Autosomal dominant

Question 13

Ehlers-Danlos syndrome

Answer 13

Autosomal dominant

Question 14

Familial adenomatous polyposis

Answer 14

Autosomal dominant

Question 15

Hereditary haemorrhagic telangiectasia

Answer 15

Autosomal dominant

Question 16

Hereditary spherocytosis

Answer 16

Autosomal dominant

Question 17

Hereditary non-polyposis colorectal carcinoma

Answer 17

Autosomal dominant

Question 18

Huntington’s disease

Answer 18

Autosomal dominant

Question 19

Hyperlipidaemia type II

Answer 19

Autosomal dominant

Question 20

Hypokalaemic periodic paralysis

Answer 20

Autosomal dominant

Question 21

Malignant hyperthermia

Answer 21

Autosomal dominant

Question 22

Marfan’s syndromes

Answer 22

Autosomal dominant

Question 23

Myotonic dystrophy

Answer 23

Autosomal dominant

Question 24

Neurofibromatosis

Answer 24

Autosomal dominant

Question 25

Noonan syndrome

Answer 25

Autosomal dominant

Question 26

Osteogenesis imperfecta

Answer 26

Autosomal dominant

Question 27

Peutz-Jeghers syndrome

Answer 27

Autosomal dominant

Question 28

Retinoblastoma

Answer 28

Autosomal dominant

Question 29

Romano-Ward syndrome

Answer 29

Autosomal dominant

Question 30

tuberous sclerosis

Answer 30

Autosomal dominant

Question 31

Von Hippel-Lindau syndrome

Answer 31

Autosomal dominant

Question 32

Von Willebrand’s disease

Answer 32

Autosomal dominant

**type 3 von Willebrand’s disease (most severe form) is inherited as an autosomal recessive trait. Around 80% of patients have type 1 disease

Question 33

Albinism

Answer 33

Autosomal recessive

Question 34

Ataxic telangiectasia

Answer 34

Autosomal recessive

Question 35

Congenital adrenal hyperplasia

Answer 35

Autosomal recessive

Question 36

Cystic fibrosis

Answer 36

Autosomal recessive

Question 37

Cystinuria

Answer 37

Autosomal recessive

Question 38

Familial Mediterranean Fever

Answer 38

Autosomal recessive

Question 39

Fanconi anaemia

Answer 39

Autosomal recessive

Question 40

Friedreich’s ataxia

Answer 40

Autosomal recessive

Question 41

Gilbert’s syndrome

Answer 41

Autosomal recessive
*although some textbooks still list as autosomal dominant

Question 42

Glycogen storage disease

Answer 42

Autosomal recessive

Question 43

Haemochromatosis

Answer 43

Autosomal recessive

Question 44

Homocystinuria

Answer 44

Autosomal recessive

Question 45

Lipid storage disease: Tay-Sach’s, Gaucher, Niemann-Pick

Answer 45

Autosomal recessive

Question 46

Mucopolysaccharidoses: Hurler’s

Answer 46

Autosomal recessive

Question 47

PKU

Answer 47

Autosomal recessive

Question 48

Sickle cell anaemia

Answer 48

Autosomal recessive

Question 49

Thalassaemias

Answer 49

Autosomal recessive

Question 50

Wilson’s disease

Answer 50

Autosomal recessive