hypotonia, symmetrical flaccid paralysis, and often no
head control. Spontaneous motility is generally poor and
antigravity movements of limbs are not typically
observed. In the most severe forms decreased intrauterine
movements suggest prenatal onset of the disease and
present with severe weakness and joint contractures at
birth and has been labeled SMN 0. Some of these children
may show also congenital bone fractures and extremely
thin ribs