basics

Question 1

What is meant by a Robertsonian translocation?

Answer 1

Fusion of 2 acrocentric chromosomes at their centromere.

Most common translocation.

Eg. 14;21

Question 2

What is meant by a Reciprocal translocation?

Answer 2

an exchange of genetic material between non-homologous chromosomes.

Question 3

What is the product of mitosis?

Answer 3

2x diploid daughter cells.
All genetically identical.

Question 4

What is the product of Meiosis?

Answer 4

4x haploid daughter cells.
All genetically different.

Question 5

What is meant by anauploid genome?

Answer 5

A genome with too many or too few chromosomes
(Not divisible by 23)

Question 6

Which sex Aneuploydies features being ‘tall’ ?

Answer 6

The ‘too manys’:

Triple X: 47 XXX
Kleinfelters: 47 XXY
47 XYY

Question 7

Which aneuploidy features short stature,
normal intelligence,
streak ovaries?

Answer 7

Turner’s

Question 8

Which aneuploidy features horse shoe kidney and aortic coarctation?

Answer 8

Turner’s

Question 9

Which cardiovascular abnormality is seen in Turner’s?

Answer 9

aortic coarctation 10-15%
(HTN)

Question 10

Which renal abnormalities feature in Turner’s syndrome?

Answer 10

Horseshoe kidney
Renal aplasia
Duplicate ureters

Question 11

Describe the characteristics of Kleinfelter’s

Answer 11

tall
normal - low intelligence
hypogonadism
- testosterone <50% of norm
- poor growth of pubertal hair
- small testes

Question 12

Why is gynaecomastia present in Kleinfelter’s?

Why is this important?

Answer 12

Imbalance of oestrogen / testosterone
-> gynaecomastia

Increased risk of breast cancer

Question 13

Which aneuploidy features early menopause

Answer 13

Triple (47) XXX

Question 14

How are micro deletion syndromes detected?

Answer 14

FISH
(florescent in situ hybridisation)

Question 15

Which microdeletion gives rise to Di George syndrome?

Answer 15

22q11

Question 16

Which microdeletion affects the elastin gene on chromosome 7?

Answer 16

William’s syndrome

Question 17

How does the microdeletion elastin gene malfunction characteristically present ?

Answer 17

supravalvular aortic stenosis
hypercalcaemia
chatty manner
low IQ

Question 18

which microdeletion syndrome features psychiatric disorder (shizophrenia) and low IQ

Answer 18

Di George

Question 19

Which microdeletion features hypocalcaemia?

Answer 19

Di George

Question 20

Which cardiac abnormalities are seen in Di George syndrome?

Answer 20

Truncus arteriosus
Interrupted aortic arch

Question 21

Regarding autosomal aneuplodies, which syndrome affects trisomy 18?

Answer 21

Edward’s

Question 22

Patau syndrome trisomy?

Answer 22

13

Question 23

Down’s syndrome:
95% non-disjunction,
5% Robertsonian translocation.. at which locus?

Answer 23

14:21

Question 24

7 phenotypic features of Down’s syndrome:

Answer 24

1. Brachycephaly
2. Moderate mental handicap
3. Protruding tongue
4. Brushfields spots (iris)
5. Hypotonia
6. Single plamar crease
7. Wide sandle gap

Question 25

Which cardiovascular malformation is a common feature of Down's syndrome?

Answer 25

AVSD

Question 26

Which common haematological abnormalities feature in Down's syndrome?

Answer 26

Acute leukemias (ALL + AML)

Question 27

Which common GI abnormalities feature in Down's syndrome?

Answer 27

Duodenal atresia, Hirschsprungs disease

Question 28

Which chromosomal aneuplody does not feature Rockerbottom feet?

Answer 28

Down's

Question 29

Which chromosomal aneuplody features overlapping fingers?

Answer 29

Edward's

Question 30

Which chromosomal aneuplody often features cleft lip / palate?

Answer 30

Patau

Question 31

Pataus and Edward' feature many similar features: name them

Answer 31

mental retardation congential heart disease renal abnormalities rockerbottom feet life expectancy = early infancy

Question 32

Name the 4 purines of DNA + their hydrogen bonds

Answer 32

Adenine - (2) - Thymine Guarnine - (3) - Cytosine

Question 33

How is RNA different to DNA?

Answer 33

Single stranded Thymine replaced by Uracil Ribose sugar backbone

Question 34

What is PCR? What does it provide?

Answer 34

Polymerase chain reaction Method to generate large volume of DNA from small sample

Question 35

Name 5 trinuceotide repeat disorders and their inheritance patterns

Answer 35

Huntington's chorea = AD Spinocerebellar ataxia = AD Myotonic dystrophy = AD Freidrich's ataxia = AR Fragile X = XLR

Question 36

Define 'expansion' in relation to repeat disorders

Answer 36

Expansion: Number of repeats above the disease causing threshold.

Question 37

Define 'anticipiation' in relation to repeat disorders

Answer 37

Anticipation: Unstable expansions enlarge in sucessive generations leading to increased disease severity.

Question 38

Explain Mitochrondrial disease inheritance

Answer 38

Mitochrondrial gene mutations are exclusively maternal.

Question 39

Give 2 examples of mitochrondrial disease

Answer 39

MELAS (mitochrondiral encephalopathy, lactic acidosis, stroke like episodes) MERRF (myoclonic epilepsy, red ragged fibres)