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Iroquois homeobox 3
Symbols IRX3 ; IRX-1; IRXB1
External IDs OMIM612985 MGI1197522 HomoloGene7385 GeneCards: IRX3 Gene
Species Human Mouse
Entrez 79191 16373
Ensembl ENSG00000177508 ENSMUSG00000031734
UniProt P78415 P81067
RefSeq (mRNA) NM_024336 NM_001253822
RefSeq (protein) NP_077312 NP_001240751
Location (UCSC) Chr 16:
54.32 – 54.32 Mb
Chr 8:
91.8 – 91.8 Mb
PubMed search [1] [2]

Iroquois-class homeodomain protein IRX-3, also known as Iroquois homeobox protein 3, is a protein that in humans is encoded by the IRX3 gene.[1]


IRX3 is a member of the Iroquois homeobox gene family and plays a role in an early step of neural development.[2] Members of this family appear to play multiple roles during pattern formation of vertebrate embryos.[1][3]

Clinical significance[edit]

Association with obesity[edit]

Obesity-associated noncoding sequences within FTO interact with the promoter of IRX3 and FTO in human, mouse, and zebrafish. Obesity-associated single nucleotide polymorphisms are related to the expression of IRX3 (not FTO) in the human brain. A direct connection between the expression of IRX3 and body mass and composition was shown through the decrease in body weight of 25-30% in IRX3-deficient mice. This suggests that IRX3 influences obesity.[4]


  1. ^ a b "Entrez Gene: iroquois homeobox 3". 
  2. ^ Bellefroid EJ, Kobbe A, Gruss P, Pieler T, Gurdon JB, Papalopulu N (January 1998). "Xiro3 encodes a Xenopus homolog of the Drosophila Iroquois genes and functions in neural specification". EMBO J. 17 (1): 191–203. doi:10.1093/emboj/17.1.191. PMC 1170370. PMID 9427753. 
  3. ^ Lewis MT, Ross S, Strickland PA, Snyder CJ, Daniel CW (June 1999). "Regulated expression patterns of IRX-2, an Iroquois-class homeobox gene, in the human breast". Cell Tissue Res. 296 (3): 549–54. doi:10.1007/s004410051316. PMID 10370142. 
  4. ^ Smemo S, Tena JJ, Kim KH, Gamazon ER, Sakabe NJ, Gómez-Marín C, Aneas I, Credidio FL, Sobreira DR, Wasserman NF, Lee JH, Puviindran V, Tam D, Shen M, Son JE, Vakili NA, Sung HK, Naranjo S, Acemel RD, Manzanares M, Nagy A, Cox NJ, Hui CC, Gomez-Skarmeta JL, Nóbrega MA (12 March 2014). "Obesity-associated variants within FTO form long-range functional connections with IRX3". Nature 507 (7492): 371–375. doi:10.1038/nature13138. PMID 24646999. 

Further reading[edit]

  • Trynka G, Zhernakova A, Romanos J, Franke L, Hunt KA, Turner G, Bruinenberg M, Heap GA, Platteel M, Ryan AW, de Kovel C, Holmes GK, Howdle PD, Walters JR, Sanders DS, Mulder CJ, Mearin ML, Verbeek WH, Trimble V, Stevens FM, Kelleher D, Barisani D, Bardella MT, McManus R, van Heel DA, Wijmenga C (2009). "Coeliac disease-associated risk variants in TNFAIP3 and REL implicate altered NF-kappaB signalling.". Gut 58 (8): 1078–83. doi:10.1136/gut.2008.169052. PMID 19240061. 
  • Ragvin A, Moro E, Fredman D, Navratilova P, Drivenes Ø, Engström PG, Alonso ME, de la Calle Mustienes E, Gómez Skarmeta JL, Tavares MJ, Casares F, Manzanares M, van Heyningen V, Molven A, Njølstad PR, Argenton F, Lenhard B, Becker TS (2010). "Long-range gene regulation links genomic type 2 diabetes and obesity risk regions to HHEX, SOX4, and IRX3.". Proc. Natl. Acad. Sci. U.S.A. 107 (2): 775–80. doi:10.1073/pnas.0911591107. PMID 20080751. 

This article incorporates text from the United States National Library of Medicine, which is in the public domain.