Passmedicine Genetics

Question 1

Congenital toxoplasmosis features

Answer 1

cerebral calcification
chorioretinitis
Hydrocephalus

Question 2

Gene associated with CML

Answer 2

ABL

Question 3

When in embryonic development does the neural tube close?

Answer 3

Week 4

Question 4

What can detect mutated oncogenes?

Answer 4

PCR

Question 5

What term is used in genetics to describe conditions with a normal phenotype despite an abnormal genotype?

Answer 5

Low penetrance

Question 6

McCune-Albright syndrome is due to a random, somatic mutation in what?

Answer 6

GNAS gene

Question 7

What gene is associated with burkitts lymphoma?

Answer 7

C-MYC

Question 8

What is fabry disease?

Answer 8

Overview
X-linked recessive
deficiency of alpha-galactosidase A

Features
burning pain/paraesthesia in childhood
angiokeratomas
lens opacities
proteinuria
early cardiovascular diseas

Question 9

Intermittent breathing movements start around what week of embryonic development?

Answer 9

10

Question 10

What is P53?

Answer 10

Tumour suppressor gene located on chromosome 17p. It is the most commonly mutated gene in breast, colon and lung cancer

p53 is thought to play a crucial role in the cell cycle, preventing entry into the S phase until DNA has been checked and repaired. It may also be a key regulator of apoptosis

Question 11

Heteroplasmy is defined as

Answer 11

presence of more than one type of organellar genome (mitochondrial DNA or plastid DNA) within a cell or individual. It results in variable expression of mitochondrial disease

Question 12

A 5-year-old boy presents to the clinic with short stature suggestive of achondroplasia. What is the genetic basis of this condition?

Answer 12

Autosomal dominant

Question 13

What does p53

Answer 13

plays a crucial role in the cell cycle, preventing entry into the S phase until DNA has been checked and repaired

Question 14

William’s syndrome is caused by what?

Answer 14

microdeletion on chromosome 7

Question 15

What is vincristine?

Answer 15

dimeric catharanthus alkaloid that acts by binding to tubulin, which disrupts microtubules and blocks metaphase in actively dividing cells.

Question 16

Burkitt’s lymphoma is commonly associated with what?

Answer 16

C-Myc

Question 17

Features of Prader-Willi syndrome?

Answer 17

hypotonia during infancy
dysmorphic features
short stature
hypogonadism and infertility
learning difficulties
childhood obesity
behavioural problems in adolescence

Question 18

Most common cause of down’s syndrome?

Answer 18

Non disjunction

Question 19

What is p53

Answer 19

Tumpur suppressor gene

Question 20

Haplo-insufficiency refers to what?

Answer 20

inability of a single allele to confer the usual phenotype to an individual

Question 21

X-linked recessive conditions means what about male to ,male transmission

Answer 21

There is no male to male transmission

Question 22

In X-linked recessive inheritance only what sex are affected

Answer 22

X linked

Question 23

Mitochondrial diseases follows a what pattern?

Answer 23

maternal inheritance pattern
Mitochondria are inherited exclusively from the ovum, and therefore there is no increased risk to the children if only the father has mitochondrial disease.

Question 24

Polymerase Chain Reaction (PCR) uses what stages?

Answer 24

denaturation, annealing and elongation to amplify a desired fragment of DNA

Question 25

Erb-B2 (HER2/neu) -

Answer 25

breast and ovarian cancer

Question 26

What is Expressivity

Answer 26

extent to which a particular genotype is expressed in the phenotype of an individual

Question 27

What is penetrance?

Answer 27

refers to the proportion of the population who have a particular mutation also having the associated disease. An example would be BRCA-1, a mutation of which causes breast cancer in 80% of those affected, giving it a penetrance of 80%.

Question 28

What is Pleiotropy

Answer 28

Condition where a single mutation causes more than one observable phenotypic effect. A well known example is PKU

Question 29

Classic triad of congenital toxoplasmosis =

Answer 29

chorioretinitis, intracranial calcifications, hydrocephalus

Question 30

This patient is presenting with clinical features consistent with Turner syndrome:

Answer 30

short stature, widely spaced nipples, webbed neck, and high-arched palate

Question 31

A 54-year-old female presents to see her GP as she has just been diagnosed with breast cancer. The underlying pathology of malignancy involves a failure of apoptosis. Where do the receptors which induce apoptosis occur within cells?

Answer 31

Membrane

Question 32

Mosaicism is defined as what

Answer 32

Presence of two genetically different populations of cells in the body

Question 33

Genetic imprinting is defined as what?

Answer 33

difference in phenotype dependent on whether the mutation is maternal or paternal origin