SAN DIEGO -- Authorities asked the public Wednesday to be on the lookout for a 21-year-old developmentally disabled East County woman who went missing this week.

April Dawn Christensen's family has not seen or heard from her since she walked away from their Boulevard-area residence early Monday afternoon, according to the sheriff's department.

Since Christensen has the approximate mental capacity of a 10-year-old and is readily trusting of strangers, her relatives are concerned that she may be victimized while away from home.

They believe an unknown person gave her a ride out of the area, possibly to San Diego, authorities said.

Christensen is white, 5-foot-4 and roughly 135 pounds, with gray-blue eyes and long, straight brown hair.

She may be wearing a dark-blue velour sweatsuit with lime-green stripes down the sides and carrying a black backpack decorated with large pink and white flowers.

Anyone with information about Christensen's whereabouts was asked to call the Sheriff's Department at (858) 565-5200.