Your Query returns 58 Accession Numbers:
Query TermAccessionNCBI TaxonidSynonymsPhenotype (OMIM) *
RPS21BC0490567955MGC56642    zgc:56642   
RpS21NM_0787387227oho23    CG2986    l(2)03575    l(2)168/14    l(2)k16814    Ribosomal protein S21    overgrown hematopoietic organs-23    oho23B   
RPS21NM_2011917955MGC56642    zgc:56642   
RpS21NM_0787387227oho23    CG2986    l(2)03575    l(2)168/14    l(2)k16814    oho23B   
RpS21NM_1645067227oho23    CG2986    l(2)03575    l(2)168/14    l(2)k16814    oho23B   
RpS21NM_1645077227oho23    CG2986    l(2)03575    l(2)168/14    l(2)k16814    oho23B   
RpS21NM_1645087227oho23    CG2986    l(2)03575    l(2)168/14    l(2)k16814    oho23B   
RpS21NT_0337797227oho23    CG2986    l(2)03575    l(2)168/14    l(2)k16814    oho23B   
RPS21NC_0011474932RPS15   
rps21AP003583103690
rps21AP003583103690
rps21AP003587103690
rps21D640001148
rps21AP005369197221
rpS21AJ5078277213
rpS21AJ0095577227
rps21AP005936224911
rps21AP006576251221
rps21AP006577251221
rpS21AE0021242130
rpS21AE006163747PM1239   
rps21AL0350774896SPBC18E5.06   
RPS21Z747824932
rps21AJ3904955476
rps21AJ0117182762
rps21AF08303155529
rps21AE016968233150
RPS21AB0618439606180477
RPS21L044839606180477
Rps21NW_04766610116
RPS21BC0181409606180477
rpS21AJ2509079606180477
RPS21AY4210509606180477
RPS21AY4210519598
RPS21AY42105210090180477
RPS21AL1218329606180477
RPS21NM_0010249606180477
Rps21BC05846410116
rps21NC_0009111148
rps21NC_003272103690
rps21NC_003272103690
rps21NC_003272103690
rps21NC_004113197221
rps21NC_004463224911
rps21NC_0034234896SPBC18E5.06   
rpS21NC_002663747
rpS21NC_0021622130
rps21NC_00507174547rpsU   
rps21NC_00507084588rpsU   
rps21NC_004829233150
rps21NC_00275155529
Rps21BC02756310090180477
RPS21NT_0308719606180477
Rps21NM_025587100901810049N11Rik    2410030A14Rik    180477
Rps21NM_03111110116
rpS21NC_00090771421
rps21NC_005125251221
rps21NC_005125251221

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

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Text2Knowledge ... Yong Huang 2002