John Mackenab and Elizebeth Dean, both of Dedham, were married December the 17, 1718.
↑Source:Cemetery Transcriptions from the NEHGS Manuscript Collection shows an entry for "Daughter John and Elizabeth (Dean) Mackenab = 17 Dec 1718". This does not make any sense because 17 Dec 1718 is the date of their marriage, but given that the first known child is not born until 1722, it does seem possible they had an earlier daughter who died young.