(NEW YORK) -- When Monica and David were born in the 1970s, children with Down syndrome had a life expectancy of under 25. Many parents were told by well-meaning doctors that their children would never walk, talk or lead meaningful lives.
Their generation defied those predictions, and now this Miami couple, both in their 30s and expected to live well beyond their 60s, has shattered misconceptions about the lives of those who are intellectually disabled.
Monica and David are married and share all its love and intimacies.
Their journey to independence with parental support is chronicled in Monica & David, which won Best Documentary Feature at the 2010 Tribeca Film Festival, and premieres October 14 on HBO.
"It gives viewers an unprecedented chance to get to know people with Down syndrome better," said Nancy Abraham, senior vice president of HBO documentary films. "It's relatable and really eye-opening."
Because the couple addresses having children, the film also is "definitely a catalyst for discussion," she said.
The film is the first by director and producer Alexandra Codina, 32, whose universal love story grew out of her close relationship with her cousin Monica, 38.
In intimate footage and personal interviews, she explores the challenges the family faces, trying to give the couple independence but, at the same time, shield them from a world that might reject them.
More than 400,000 Americans are living with Down syndrome -- born with three, rather than two, copies of the 21st chromosome, according to the National Down Syndrome Society (NDSS).
Their cognitive abilities are varied -- some are profoundly incapacitated while others are very high-functioning -- but their need for love, affection and acceptance is as ordinary as all adults.
They have an increased risk for heart defects, respiratory and hearing problems, Alzheimer's disease, childhood leukemia and thyroid conditions. But because many of these conditions are now treatable, most now lead healthy lives.
And now, with more social acceptance, a small, but growing number of those adults are taking marriage vows.
"One of the biggest misconceptions is they are angelic, always happy," said Codina. "But loneliness is very typical and a difficult experience for a lot of adults with disabilities. Even if the mainstream environment is still fighting against the stigma, they have to work harder to live an ordinary life."
Monica and David live in a separate apartment under the close supervision of her mother, Maria Elena, and stepfather, Bob, who try to respect their privacy while helping to structure their daily lives.
But even those close to the couple struggle to view them as fully actualized adults.
"Monica and David's love and their desire for an adult life is very real," she said. "Like all issues relating to adults with intellectual disabilities -- dating, marriage, housing, employment, education, the future, and parents' roles -- there is no clear line. Monica and David are adults capable beyond traditional expectations, but they can also be childlike and need assistance."
Copyright 2010 ABC News Radio