▁may ▁also ▁m im ic ▁hay ▁fe ver ▁or ▁include ▁der mat itis ▁or ▁h ives , ▁and , ▁in ▁severe ▁cases , ▁may ▁cause ▁breath ing ▁problems . ▁Prote omic ▁studies ▁indicate ▁that ▁the ▁aller gen ▁may ▁be ▁tied ▁to ▁a ▁protein ▁for ▁the ▁red ▁anth oc yan in ▁b ios yn thesis ▁expressed ▁in ▁st raw berry ▁rip ening , ▁named ▁Fra ▁a 1 ▁( F rag aria ▁aller gen 1 ). ▁Hom olog ous ▁prote ins ▁are ▁found ▁in ▁bir ch ▁pol len ▁and ▁apple , ▁suggesting ▁that ▁people ▁may ▁develop ▁cross - react ivity ▁to ▁all ▁three ▁species . ▁ ▁White - f ru ited ▁st raw berry ▁cultiv ars , ▁lack ing ▁Fra ▁a 1 , ▁may ▁be ▁an ▁option ▁for ▁st raw berry ▁aller gy ▁suffer ers . ▁Since ▁they ▁lack ▁a ▁protein ▁necessary ▁for ▁normal ▁rip ening ▁by ▁anth oc yan in ▁synth esis ▁of ▁red ▁p ig ments , ▁they ▁do ▁not ▁turn ▁the ▁m ature ▁ber ries ▁of ▁other ▁cultiv ars ▁red . ▁They ▁rip en ▁but ▁remain ▁white , ▁pale ▁yellow ▁or ▁" g old en ", ▁appearing ▁like ▁imm ature ▁ber ries ; ▁this ▁also ▁has ▁the ▁advantage ▁of ▁making ▁them ▁less ▁attract ive ▁to ▁birds . ▁A ▁virt ually ▁aller gen - free ▁cultiv ar ▁named ▁' S of ar ' ▁is ▁available . ▁ ▁See ▁also ▁▁▁ ▁California ▁St raw berry ▁Commission ▁ ▁Fra ise ▁Tag ada ▁( st raw berry - sh aped ▁c andy ▁popular ▁in ▁France )