▁express ivity ▁of ▁the ▁disease . ▁ ▁M ilder ▁forms ▁of ▁the ▁disease , ▁seen ▁in ▁those ▁who ▁live ▁beyond ▁the ▁ne on atal ▁period ▁and ▁those ▁with ▁A CD , ▁may ▁be ▁att rib utable ▁to ▁som atic ▁m osa ic ism — part icular ly ▁for ▁those ▁with ▁mut ations ▁within ▁the ▁SO X 9 ▁coding ▁region . ▁ ▁Ch rom os om al ▁aber r ations ▁in ▁the ▁up stream ▁control ▁regions ▁or ▁resid ual ▁activity ▁of ▁the ▁mut ant ▁SO X 9 ▁protein ▁could ▁also ▁be ▁responsible ▁for ▁the ▁mil der ▁forms ▁of ▁the ▁disease . ▁ ▁Long - term ▁surv iv ors ▁of ▁C MD ▁are ▁significantly ▁more ▁likely ▁to ▁have ▁trans location ▁and ▁in version ▁mut ations ▁up stream ▁of ▁SO X 9 ▁rather ▁than ▁mut ations ▁in ▁the ▁SO X 9 ▁coding ▁region ▁itself . ▁ ▁Di agn osis ▁In ▁u tero ▁son ographic ▁diagn osis ▁is ▁possible ▁when ▁characteristic ▁features ▁such ▁as ▁bil ater al ▁bow ed ▁fem urs ▁and ▁tib ia , ▁club bed ▁feet , ▁prominent ▁curv ature ▁of ▁the ▁neck , ▁a ▁bell - sh aped ▁ch est , ▁pel vic ▁d ilation , ▁and / or ▁an ▁unders ized ▁j aw ▁are ▁apparent . ▁ ▁Rad i ographic ▁techniques ▁are ▁generally ▁used ▁only ▁post nat ally ▁and ▁also ▁rely ▁on ▁pro tot yp ical ▁physical ▁characteristics . ▁ ▁Screen ing ▁ ▁Gen etic ▁screen ing ▁is ▁also ▁typically ▁done ▁post nat ally , ▁including ▁PC R ▁typing ▁of ▁mic ros at