▁at ▁which ▁the ▁hydro x yl ase ▁breaks ▁down ▁the ▁phen yl al an ine . ▁This ▁is ▁what ▁causes ▁the ▁phen yl al an ine ▁to ▁build ▁up ▁in ▁the ▁body . ▁The ▁way ▁to ▁treat ▁PK U ▁is ▁to ▁manage ▁one ' s ▁di et . ▁Ph en yl al an ine ▁is ▁ing ested ▁through ▁food , ▁so ▁a ▁di et ▁should ▁decrease ▁types ▁of ▁food s ▁that ▁have ▁high ▁amounts ▁of ▁phen yl al an ine . ▁Food s ▁with ▁high ▁levels ▁of ▁protein ▁must ▁be ▁avoided . ▁These ▁include ▁breast ▁milk , ▁eggs , ▁ch icken , ▁be ef , ▁p ork , ▁fish , ▁n uts , ▁and ▁other ▁food s . ▁A ▁special ▁PK U ▁formula ▁can ▁be ▁obtained ▁in ▁order ▁for ▁the ▁body ▁to ▁have ▁protein . ▁ ▁S ick le ▁cell ▁an emia ▁▁ ▁S ick le ▁cell ▁an emia ▁is ▁a ▁gen etic ▁disease ▁that ▁causes ▁de formed ▁red ▁blood ▁cells ▁with ▁a ▁rig id , ▁cres cent ▁shape ▁instead ▁of ▁the ▁normal ▁flexible , ▁round ▁shape . ▁It ▁is ▁caused ▁by ▁a ▁change ▁in ▁one ▁nucle ot ide , ▁a ▁point ▁mut ation ▁in ▁the ▁H BB ▁gene . ▁The ▁H BB ▁gene ▁enc odes ▁information ▁to ▁make ▁the ▁beta - g lo bin ▁sub unit ▁of ▁hem og lo bin , ▁which ▁is ▁the ▁protein ▁red ▁blood ▁cells ▁use ▁to ▁carry ▁o xygen ▁throughout ▁the ▁body . ▁S ick le ▁cell ▁an emia ▁occurs ▁when ▁the ▁H BB ▁gene ▁mut ation