Are scientist able to correct mutiple gene defect in our body by using CRISPR
Certainly not yet - there is not yet any evidence that this can be used to correct specific deficiencies in an adult, though the in vivo applications are growing.

In particular, an exciting recent advance is the opportunity to better understand carcinogenesis by 'editing in' certain known mutations into a mouse, say, that should cause a cancer, and watching for when the cancer actually arises...