filling missing values in only typed SNPs - Does it need imputed or just phased?

Question

[phuongthaod04]

Hi,

I am new in bio field so my knowledge is not deep enough to sold this question. Please give me a help.

I have a data of more than 2000 individuals with 70 SNPs typed, containing missing values.

I would like to fill these missing values in only such 70 SNPs, using reference data.

My question is should I need to phase it with SHAPEIT, and then impute the data using IMPUTE2

OR

I just need to phase it using SHAPEIT, because the SNPs already typed and I don't need other untyped SNPs.

Thank you!

Viola