e par v ove c ▁was ▁approved ▁in ▁the ▁US ▁as ▁a ▁treatment ▁for ▁children ▁under ▁ 2 4 ▁months . ▁Out comes ▁vary ▁by ▁type ▁from ▁a ▁life ▁expect ancy ▁of ▁a ▁few ▁months ▁to ▁m ild ▁mus cle ▁weak ness ▁with ▁a ▁normal ▁life ▁expect ancy . ▁The ▁condition ▁affect s ▁about ▁ 1 ▁in ▁ 1 0 , 0 0 0 ▁people ▁at ▁birth . ▁ ▁Classification ▁S MA ▁manifest s ▁over ▁a ▁wide ▁range ▁of ▁sever ity , ▁affect ing ▁inf ants ▁through ▁adult s . ▁The ▁disease ▁spectrum ▁is ▁various ly ▁divided ▁into ▁ 3 – 5 ▁types , ▁in ▁accord ance ▁either ▁with ▁the ▁age ▁of ▁on set ▁of ▁sympt oms ▁or ▁with ▁the ▁highest ▁att ained ▁mil estone ▁of ▁motor ▁development . ▁ ▁The ▁most ▁commonly ▁used ▁classification ▁is ▁as ▁follows : ▁ ▁The ▁most ▁severe ▁form ▁of ▁S MA ▁type ▁I ▁is ▁sometimes ▁term ed ▁S MA ▁type ▁ 0 ▁( or , ▁severe ▁infant ile ▁S MA ) ▁and ▁is ▁diagn osed ▁in ▁b ab ies ▁that ▁are ▁born ▁so ▁weak ▁that ▁they ▁can ▁surv ive ▁only ▁a ▁few ▁weeks ▁even ▁with ▁int ensive ▁resp ir atory ▁support . ▁S MA ▁type ▁ 0 ▁should ▁not ▁be ▁confused ▁with ▁S MA R D 1 ▁which ▁may ▁have ▁very ▁similar ▁sympt oms ▁and ▁course ▁but ▁has ▁a ▁different ▁gen etic ▁cause ▁than ▁S MA . ▁ ▁Motor ▁development ▁in ▁people ▁with ▁S MA ▁is ▁usually ▁ass essed ▁using ▁valid ated ▁functional ▁scales ▁– ▁CH OP