The family of a student from west London who has been missing for a week say they are becoming increasingly worried about his safety.
Richard Okorogheye, 19, has been shielding throughout the coronavirus pandemic because he has sickle cell disease, which affects how red blood cells work in the body.
His mother, Evidence Joel, said he left the family home in the Ladbroke Grove area on 22 March.
He said he was going to see a friend.
Ms Joel, a nurse, said she returned home from work at about 21:00 GMT and assumed her son - who had only been leaving the house for his regular blood transfusions - was back home and in his bedroom.
But Richard has not been seen since, and he did not take his wallet, bus pass or bank card with him.
Ms Joel said her son, who has also in the past been known to frequent the Westminster, Hammersmith and Fulham areas, had been "struggling to cope" with his university course.
He is in the first year of a business and IT degree at Oxford Brookes.
The Met said it was "following every lead possible" to find the teenager; speaking with witnesses and examining CCTV.