SINGAPORE - All three of Mr David Lang's children were born healthy, zipping through development milestones as they grew up. Justina, the eldest, could name 100 objects in a picture book at the age of one. Timothy, the middle child, would try and read everything he could. Titus, the youngest, could solve a Primary 2 mathematics problem when he was in kindergarten. But as they each grew older, they started falling more frequently when running, spoke less, and had seizures. Initially, Mr Lang, 63, and his wife, Mrs Lang Loo Geok, 62, suspected attention deficit hyperactivity disorder. Doctors attributed the falling to clumsiness and teachers thought they had behavioural problems. But it turned out to be Niemann-Pick disease type C, which causes cognitive and physical functions to degenerate. There are an estimated 500 cases diagnosed worldwide, according to the National Niemann-Pick Disease Foundation. It is fatal and incurable. In 2004, Timothy died at the age of 10. Titus, now 24, and Justina, 30, are unable to walk, stand, sit without support, talk, eat, drink or swallow their saliva. They are tube-fed and breathe through tracheostomy tubes. Because they require round-the-clock ca...