shevyatiwari's version from 2015-04-25 00:22


Question Answer
G6PD reduces NADP to NADPHT
NADPH increases glutathioneF, decreases
PPP (pentose phosphate pathway) is the only source of NADPH in erythrocytesT as they lack mitochondria. G6PD deficient erythrocytes are exquisitely sensitive to oxidative stressors
Polymorphisms noted on Y chromosomeF, X chromosome
Aspartic acid is substituted for asparagine in G6PD deficiencyF, other way around
Higher incidence of deficiency in malaria endemic areasT - evolutionary advantage
Most drugs rely on G6PD for phase 1 metabolismF, phase II
Quantitative evaluation of ability to reduce NADP to NADPH in erythrocytes is part of testingT
Fluorescent spot test is a method of testingT - others including methemoglobin or Nile blue sulphate are more accurate
Recent haemolysis and blood transfusion can both yield inaccurate resultsT
Sporadic mutations are commonF - that's why family testing is useful
Primaquine causes haemolysis in G6PDT
Chloroquine and hydroxychloroquine cause haemolysis in G6PD deficientF, minimal
Fluorescent spot test allows direct visualisation of a fluorescently tagged NADPF, NADPH
Woman with heterozygous G6PD mutation can have two populations of erythrocytes - one with G6PD and the other without G6PD activityT - therefore fluorescent test not always reliable
Methemoglobin and Nile blue sulphate measure activity in individual erythrocytesT


Question Answer
Involved in phase II metabolism of 5 FUF, phase 1
Deficiency -> hepatotoxicityF - neurotoxicity, GI and haematological
Many genetic variations of DPDT
Routine screening is standard of careF
Deficiency in DPD*2A is associate with leukopenia and mucositisT


Question Answer
MDR1 codes for PGPT
Decreased PGP cause increased drug concentration with warfarinF, digoxin
There is no ethnic variabilityF
Overlap of substrates with CYP2D6F, 3A4


Question Answer
High levels of 6TG is associated with haematological toxicityT
TPMPT deficiency is associated with lower levels of hepatotoxicityT, as hepatotoxicity is mediated by 6-MMP
Significant polymorphismsT
3 mutant allelesT
Heterozygous expression of mutant alleles with TPMT*1 is low activityF intermediate
Homozygous expression of 2 mutant alleles is low activityT, or heterozygous
Significant variation between ethnic groupsT
Enzyme activity can be affected by medications, recent blood transfusions, tobacco, impaired renal functionT
Genotyping is affected by environmental factorsF
Deficient patients should have dose reduction by 15-50%F, that's intermediate patients.
Deficient patients should have dose reduction by 90% or not be given AztT