SCID

Question 1

What is SCID characterized by?

Answer 1

Severe opportunistic infections such as candidiasis or jiroveci, chronic diarrhea and failure to thrive in infancy
Mostly autosomal inheritance

Question 2

What is the right form of tx for all SCIDs?

Answer 2

HSCT

Question 3

Which vaccines should be avoided for SCID diseases?

Answer 3

Live vaccines should be avoided

Question 4

Which forms of SCID have B cells present?

Answer 4

PNP, deficiency of Jak3 and DiGeorge Syndrome

Question 5

Which forms of SCID do NOT have B cells?

Answer 5

ADA, RAG1/2 and Artemis deficiency

Question 6

What is purine nucleoside phosphorylase (PNP) deficiency?

Answer 6

T-B+NK+/-
Normal Ig levels
Accumulation of dGTP which is toxic and leads to a decrease in peripheral T cells but normal B cells
Common autoimmune disorders: hemolytic anemia, thyroid disease, arthritis and lupus

Question 7

What is deficiency of Jak3?

Answer 7

T-B+NK-
IgM+, low everything else
Mutation in gene encoding for Jak3 leading to a defect in IL-2R signaling

Question 8

What is DiGeorge syndrome?

Answer 8

T-B+NK+
Normal Ig levels
Deletion of 22q
Classic triad: cardiac anomalies, Hypocalcemia and hypoplastic thymus leading to T cell dysfunction

Question 9

What is ADA deficiency?

Answer 9

T-B-NK-
Low/absent Ig levels
ADA converts adenosine -> inosine
Mutation leads to accumulation of deoxyadenosine (toxic to lymphocytes)

Question 10

What is RAG1/2 deficiency?

Answer 10

T-B-NK+
Low/absent Ig levels
Impaired VDJ recombination leading to defective expression of pre-BCR and pre-TCR

Question 11

What is Artemis decency?

Answer 11

T-B-NK+
Low/absent Ig levels
Rare from of SCID with radiosensitivity
Increased risk of developing lymphomas