“US person” means a US citizen or resident individual, a partnership or corporation organized in the US or under the laws of the US or any state thereof, a trust if (i) a court within the US would have authority under applicable law to render orders or judgments concerning substantially all issues regarding administration of the trust, and (ii) one or more US Persons have the authority to control all substantial decisions of the trust, or an estate of a decedent that is a citizen or resident of the US.
Generally, a US Person would also include US tax residents, as well as individuals whose place of birth is in the US (except where the US citizenship has been relinquished).
What if I have a MyPR?
As long as you are a US citizen, you are subject to FATCA requirements.