Mohammad Azzam Javeed, from Levenshulme, Manchester, is thought to have travelled at the same time as suspected jihadist Anil Khalil Raoufi.
He had been due to start a chemical engineering degree but went to Syria.
Counter-terrorism police confirmed a search had been carried out at a property in Levenshulme in December.
The BBC's Asian Network has learned Azzam Javeed went abroad at about the same time as his friend Anil Khalil Raoufi.
It is believed Raoufi, 20, of Didsbury, Manchester, who has family links in Afghanistan, was killed in a gun battle with Syrian government forces earlier this month.
His father declined to be interviewed but confirmed he had not heard from his son since he went to Syria last Autumn.
The family say they are distraught as they have not heard from him for several months and do not know if he has been killed or captured.
The UK government believes around 240 British men are fighting in Syria and is concerned that some may use their military skills and training when they return to the UK. The Foreign Office has advised against all travel to the country.
Azzam Javeed's last posting on his Facebook site was on 22 September.
A spokesman for the North West Counter-Terrorism Unit said: "We don't comment on individual cases but do say that anyone who goes there [Syria] will attract the attention of the UK authorities because there are a number of extremist groups operating."
You can can hear more on BBC Asian Network Reports at 13:00 GMT and 17:00.
A 19-year-old Briton believed to have travelled to Syria with a friend who was later killed in a gun battle, has gone missing in the country.