Your Query returns 8 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
nkx2-2NM_13142279555090    nk2.2    id:ibd5090    nkx2.2   
Nkx2-2NM_01091910090Nkx2.2    tinman    Nkx-2.2   
NKX2-2AY4102239606
NKX2-2AY4102249598
NKX2-2AY41022510090
NKX2-2NM_0025099606NKX2B    NKX2.2   
Nkx2-2NT_03921010090
NKX2-2NT_0113879606

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

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Text2Knowledge ... Yong Huang 2002