Your Query returns 2 Accession Numbers:

Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
SYN1aNM_0069509606SYNI    SYN1b    SYN1   
SYN1aNM_1334999606SYNI    SYN1b    SYN1   

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

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Text2Knowledge ... Yong Huang 2002