One option is to do the following:
DECLARE @PageSize INT
DECLARE @Page INT
SELECT @PageSize = 100,@Page = 2
;WITH temp_table AS(
Select RegNo, PatientName, FCNo, RelationName, G.Description Gender, DATEDIFF(YYYY,DOB,GETDATE())'Age', R.Deleted, ROW_NUMBER() OVER(ORDER BY RegNo) ID from PRS.dbo.tblRegistration R LEFT OUTER JOIN TKC.dbo.tblGender G ON R.GenderID=G.GenderID
)
SELECT * FROM temp_table WHERE ID BETWEEN ((@Page - 1) * @PageSize + 1) AND (@Page * @PageSize)
This can be in an SP, to which you can pass pagesize and page as parameters..