Your Query returns 2 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
ADRB2RBC0124819606ADRBR    BAR    B2AR    ADRB2   
ADRB2RNM_0000249606BAR    B2AR    ADRBR    BETA2AR    ADRB2   

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

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Text2Knowledge ... Yong Huang 2002