Tuberculosis Susceptibility Genes

Question 1

The development of tuberculosis in humans depends on which two factors?

Answer 1

Environmental and genetic factors

Question 2

The susceptibility genes to TB are found on which locus?

Answer 2

The BCG locus - which encodes a single gene

Question 3

Which name and describe the 2 BCG genotypes (in mice)

Answer 3

BCGS - s for susceptible to TB
BCGR - r for resistance to TB
They differ by 1 single aa

Question 4

What is the human homologue of the BCG gene

Answer 4

NRAMP1 - Natural resistance associated macrophage protein 1

Question 5

What does NRAMP1 encode?

Answer 5

It encodes a protein located in the late endocytic compartment which is recruited to the phagosome during active phagocytosis and thus inhibit the replication of intracellular pathogens (it may also control the transport of divalent cations)

Question 6

How many NRAMP1 polymorphisms exist?

Name those which make patients susceptible to TB

Answer 6

4

INT4 and 3UTR heterozygous patients are often found in patients with tuberculosis

Question 7

Are TB susceptibility genes dominant or recessive?

Answer 7

Susceptibility genes are dominant in humans

Resistance genes are dominant in mice