P6 BIOCHEMSIRTY

Question 1

severe form of primary heritable immunodeficiency; profound defect in cellular and humoral immunity

Answer 1

severe combined immunodeficiency

Question 2

enzyme that is expressed intracellularly & on cell surface with CD26

Answer 2

Adenosine deaminase

Question 3

ADA is found highest in

Answer 3

thymus , brain , Gi tract

Question 4

genetic predisposition of ADA def.

Answer 4

Autosomal recessive

Question 5

most common form of SCID

Answer 5

X-linked / gamma SCID

Question 6

def. of ADA causes accumulation of

Answer 6

• 2 deoxyadenosine
  -deoxyadenosine triphosphate (dATP)

Question 7

Treatment of ADA def.

Answer 7

BM transplantation
enzyme replacement therapy

Question 8

PNP is expressed highly in

Answer 8

thymus , lymph nodes

Question 9

guanine & hypoxanthine are released upon cleavage of what substances

Answer 9

guanosine , inosine ,deoxyguanosine and deoxyinosine,

Question 10

genetic predisposition of PNP def.

Answer 10

Autosomal recessive

Question 11

levels of nucleoside substrates in PNP def.

Answer 11

Increased

Question 12

levels of uric acid in PNP def.

Answer 12

Decreased

Question 13

in PNP def.
Abundance of what substance is responsible for lymphotoxicity

Answer 13

overabundance of dGTP

Question 14

dGTP is a potent feedback inhibitor of

Answer 14

ribonucleotide reductase

Question 15

fate of guanine and hypoxanthine

Answer 15

• salvaged as precursors for ATP & GTP
• oxidised to uric acid

Question 16

2’deoxyadenosine irreversibly inhibits what enzyme

Answer 16

S- adenosylhomocysteine hydrolase

Question 17

accumulation of deoxyadenosine triphosphate (dATP) leads to

Answer 17

Inhibition of ribonucleotide reductase