Siblings 

U.S. Citizen: A United States citizen may apply for his or her siblings.

The sibling of a United States citizen is not an immediate relative. The sibling is assigned to the F4 category (siblings of U.S. citizen).

A sibling of a United States citizen can have derivatives attached to his or her application meaning that the person’s spouse or unmarried children under the age of 21 may be eligible for an immigrant visa through the principal beneficiary’s application.

Lawful Permanent Resident: A lawful permanent resident cannot apply for his or her siblings.