Genetic

Question 1

X linked recessive

Answer 1

Only males affected except in Turner’s

Son of carrier 50% chance affected, daughter 50% chance carrier

Question 2

Autosomal recessive

Answer 2

Metabolic 
Only homozygous affected 
Makes and females equal Chance 
Carrier parent, child 25% affected, 50-% carrier
Can skip a generation

Question 3

Autosomal dominant

Answer 3

Structural
All offspring 50% inheritance
No carriers
Non penetrance - lack of clinical signs and symptoms eg otosclerosis 40%
Spontaneous mutation eg achondroplasia 80% unaffected parents

Question 4

X linked dominant

Answer 4

Woman has 50% chance will pass on

Son of father with disorder not affected

Question 5

Trinueotide repeat

Answer 5

Anticipation - earlier onset, and usually worse severity
Unstable expansions
Dominance of neuro

Question 6

CGC

Answer 6

Fragile X

Question 7

CAG

Answer 7

Huntington’s

Question 8

CTG

Answer 8

Myotonic dystrophy

Question 9

GAA

Answer 9

Friedrich’s ataxia

Question 10

Mitochondrial disease

Answer 10

Only via maternal line
- all children of mother and bone of father will inherit
Generally neuro
Heteroplasmy, can be different mitochondrial populations within a cell

Question 11

P53

Answer 11

Tumour suppressor
On Chr17p
Breast, colon, lung Ca
Preventing entry into S phase until dna has been checked

Question 12

Li Frameni

Answer 12

AD
Early onset of cancers eg sarcoma and breast
Mutations P53

Question 13

Downs

Answer 13

Trisomy 21 or G
Males infertile, females subfertile
Endocardial cushion defect (avsd)
ALL
1/1000 risk at 30, then x3 every 5years

Question 14

Turner’s

Answer 14

1/2500
XO
Only one X or deletion or short arm of one X
Increased AI disease

Question 15

Klinefelter’s

Answer 15

Hypogonadotrophic hypogonadism

Karyotype 47 XXY

LH and FSH raised

Question 16

Kallman’s syndrome

Answer 16

X linked recessive trait - hypogonadotrophic hypogonadism causing delayed puberty
Failure of GnRH secreting neurons to migrate to hypothalamus
lack of smell

LH and FSH low-normal

Question 17

Marfan’s

Answer 17

Autosomal dominant connective tissue disorder
Defect in fibrillin-I gene on Chr 15

*cardiac problems: dilation aortic sinuses 90% -> AR, mitral valve prolapse and dissection

Question 18

Noonan syndrome

Answer 18

Autosomal dominant
Normal karyotype
Defect in gene on Chr12

Question 19

Patau syndrome

Answer 19

Trisomy 13 or D
Non-dysfunction during meiosis
Increased risk with increased maternal age
Average 1/25,000 births

Question 20

Prader Willi

Answer 20

Genetic imprinting - phenotype depends on if deletion occurs on maternal/paternal inherited gene
Absence of gene on long arm of Chr15

• prader willi if from father
• angelman from mother

Question 21

Edwards

Answer 21

Trisomy 18 or E
Second most common autosomal trisomy after Downs
Very low rate of survival - cardiac and kidney problems

Question 22

Anti-GAd autoantibodies

Answer 22

70-90% type 1 diabetes

Question 23

Anti thyroid peroxidase antibodies

Answer 23

Graves’ disease

Hashimoto’s