Your Query returns 6 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
B7-1NM_00985510090Ly53    Cd28l    Ly-53    MIC17    TS/A-1    Cd80   
B7-1NM_01292610116Cd80   
B7-1AF2576539615
B7-1U3306310090
B7-1U1092510116
B7-1U2683210090

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

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Text2Knowledge ... Yong Huang 2002