Your Query returns 4 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
Nkx-2.5NM_00870010090Csx    Nkx2.5    tinman    Nkx2-5   
nkx-2.5AJ2913129986
Nkx-2.5AB0211339606
Nkx-2.5AF09135110090

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

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Text2Knowledge ... Yong Huang 2002