▁same ▁chrom os ome , ▁which ▁makes ▁it ▁possible ▁to ▁be ▁a ▁car rier ▁by ▁having ▁one ▁chrom os ome ▁with ▁two ▁copies ▁and ▁a ▁second ▁chrom os ome ▁with ▁zero ▁copies . ▁This ▁situation ▁will ▁lead ▁to ▁a ▁false ▁negative ▁result , ▁as ▁the ▁car rier ▁status ▁will ▁not ▁be ▁correctly ▁detected ▁by ▁a ▁traditional ▁gen etic ▁test . ▁ ▁Rout ine ▁screen ing ▁▁ ▁Rout ine ▁pr en atal ▁or ▁ne on atal ▁screen ing ▁for ▁S MA ▁is ▁controvers ial , ▁because ▁of ▁the ▁cost , ▁and ▁because ▁of ▁the ▁sever ity ▁of ▁the ▁disease . ▁Some ▁research ers ▁have ▁concluded ▁that ▁population ▁screen ing ▁for ▁S MA ▁is ▁not ▁cost - effect ive , ▁at ▁a ▁cost ▁of ▁$ 5 ▁million ▁per ▁case ▁a vert ed ▁in ▁the ▁United ▁States ▁as ▁of ▁ 2 0 0 9 . ▁O thers ▁conclude ▁that ▁S MA ▁meets ▁the ▁criteria ▁for ▁screen ing ▁programs ▁and ▁relevant ▁testing ▁should ▁be ▁offered ▁to ▁all ▁cou ples . ▁The ▁major ▁argument ▁for ▁ne on atal ▁screen ing ▁is ▁that ▁in ▁S MA ▁type ▁I , ▁there ▁is ▁a ▁critical ▁time ▁period ▁in ▁which ▁to ▁initi ate ▁ther ap ies ▁to ▁reduce ▁loss ▁of ▁mus cle ▁function ▁and ▁pro active ▁treatment ▁in ▁regards ▁to ▁nut r ition . ▁ ▁Management ▁ ▁The ▁management ▁of ▁S MA ▁var ies ▁based ▁upon ▁the ▁sever ity ▁and ▁type . ▁In ▁the ▁most ▁severe ▁forms ▁( types ▁ 0 / 1 ), ▁individuals ▁have ▁the ▁greatest ▁mus cle ▁weak ness