It is also called Dubowitz disease. It is identified by muscle weakness that develops in children between ages 6 and 12 months. They usually cannot sit without support. Apart from difficulty sitting, they usually cannot stand nor walk without help. Other signs include involuntary trembling (tremors) in their fingers, develop scoliosis, and respiratory muscle weakness that can be life-threatening. Many individuals with this type of condition often can only live up to their twenties or thirties.