How to calculate "expected loss-of-function variants" for a gene

Question

[Shicheng Guo]

Hi All,

Who can help me to explain how to calculate "expected loss-of-function variants" for a gene? any formula?

a gene with a LoF oe of 0.4 can clearly be interpreted as a gene where only 40% of the expected loss-of-function variants were observed and therefore is likely under selection against LoF variants. In addition, the oe 90% CI allows us to clearly distinguish cases where there is a lot of uncertainty about the constraint for that gene due to sample size.

Thanks