Your Query returns 2 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
Nkx2.6NM_01092010090Tix    tinman    Nkx-2.6    Nkx2-6   
Nkx2.6AF03011310090

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

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Text2Knowledge ... Yong Huang 2002