False about myositis ossificans progressiva (child with heterotopic ossification) is?

Myositis ossificans progressiva is a autosomal dominant disease is characterized by heterotopic ossification most commonly involving spine and congenital deformities of hand and feet. The disease usually stas before 6 years of age. In myositis ossificans progressiva, the life expectancy is decreased and the commonest cause of death is lung diseases. Ref: Harrison 17/e, Page 2416.