Negative values for PhenoAge Clock

[wwangbl]

Hello,

Thanks for your work! I have a question regarding PhenoAge (LevineM2018). In my calculations using methyAge, I got negative values when the chronological age is small (normally occur when chronological age is below 10). May I know what may cause this and whether this is normal?

Furthermore, I'd like to know what imputation methods are used when the input data has missing entries.

Thank you!

[yiluyucheng]

It is normal to get negative values from PhenoAge.
For imputation, the package replaces NAs with samples mean or golden reference which is mean beta values generated from GSE55763.