Does anyone know the 3 intermediates that accumulate in PK-deficiency (pyruvate kinase deficiency)?

How to answer this question.
1) work out what reaction the enzyme is involved in (glycolysis)
2) Work out which specific reaction it does
3) find a diagram/ flow chart of glycolysis
4) draw on where PK works
5) Look at upstream form the reaction, what reactions can take place but cannot proceed down the glycolysis pathway because PK is down?

For example the Y gene is knocked out
top line = reactions
bottom line = enzymes

A ----> B -------> C ---------->D
__ X_______Y________Z

This means you make a lot of B but it can't be converted into C
So you will accumulate B and A

Thanks man