Recurring.
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pal·in·dro·mic .pal-ən-'drō-mik adj
1) RECURRENT <\palindromic rheumatism>
2) of, relating to, or consisting of a double-stranded sequence of DNA in which the order of the nucleotides is the same on each side but running in opposite directions
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adj.
relapsing: describing diseases or symptoms that recur or get worse.
Medical dictionary. 2011.