Your Query returns 6 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
CD21NM_00775810090Cr1    CD35    Cr-1    Cr-2    Cr2   
CD21NM_0018779606C3DR    CR2   
cd21AJ5353179913
cd21AJ0115129606
cd21X982579606
Cd21AF16868310090

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* OMIM link based on symbol match for human and mouse.

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Text2Knowledge ... Yong Huang 2002