SCID

Question 1

What is SCID?

Answer 1

severe combined immunodeficiency disorder

Question 2

What is the presentation of SCID?

Answer 2

• Usually well for first 3 months of life v
• Has persistent superficial candida
• Diarrhoea and failure to thrive
• Chronic bronchiolitis
• Intersistial pneumonitis
• Overwhelming bacterial sepsis

Question 3

What is the treatment of SCID

Answer 3

• Nutritional support
• Prophylactic and therapeutic antibodies, antivirals and antifungals
• Suitable bone marrow transplant- needs to be done EARLY
• Stem cell transplant
• Gene therapy
• Some countries scan for SCID

Question 4

What causes SCID?

Answer 4

Defective development of B and T cell series

Question 5

what is the history of someone who has SCID?

Answer 5

• Family history of neonatal death

* Family history of consanguinity

Question 6

what are the pre-requisites for

Answer 6

1. The genetic mutation for each patient must be identified, and there must be evidence that correcting the mutation will improve his or her condition.
2. The transfected gene must confer a proliferation or survival advantage.
3. Gene therapy must not cause malignancy.

Question 7

What is the mechanism for gene therapy

Answer 7

• Gene therapy uses recombinant technology to correct the genetic defect in the patient’s own stem cells, which can then reconstitute the immune system.
• used in patients with SCID for whom no suitable stem cell donor was available.

Question 8

What should be measured?

Answer 8

• IgG, IgA, and IgM should be measured.
• With low levels of immunoglobulins, causes of secondary immunodeficiency (renal disease/ gut disease) should be excluded.
• If total Igs are normal, specific antibodies against Haemophilus spp. and pneumococcus should be measured.
• If these tests are all normal, it is important to check no problems are apparent with complement or neutrophil function.

Question 9

what precautions should be taken before definite treatment?

Answer 9

• Avoiding live vaccines (eg, measles, mumps, rubella, polio)
• Prophylaxis against opportunist infections such as Pneumocystis jiroveci

Question 10

what is the success rate of SCT?

Answer 10

90%

Question 11

How does gene therapy work?

Answer 11

• Viral constructs and stem cells are mixed in vitro
• Viral constructs contain the gamma gene which the stem cells do not
• The stem cell now present the gamma gene
• stem cells now return the the patient and begin to proliferate