Your Query returns 3 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
Pmx2NM_00888710090Arix    Phox2    Pmx2a    Phox2a   
PMX2BC0146459606PRRX2   
PMX2NM_0163079606PRX2    MGC19843    PRRX2   

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

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Text2Knowledge ... Yong Huang 2002