Table I.

Review of studies on the relationship between expression of IRX3 and FTO

No.	Reference	Study design	Sample characteristic	Examined components	Main findings
1	Ragvin (2010) [20]	Experimental	Zebrafish	IRX3 and SOX4, HHEX expression	Areas of FTO non-coding genes and CDKAL1 influence obesity and type 2 diabetes by affecting transcription factors of IRX3, SOX4 and HHEX genes
2	Smemo (2014) [15]	Experimental	Mice	IRX3 expression	Sequence of FTO gene had an interaction with promoter region of IRX3 gene, and polymorphism of FTO gene had a relationship with expression of IRX3 gene in human brain
3	Ronkainen (2015) [23]	Experimental	Mice	IRX3 expression	Expression rate of IRX3 gene in those mice without FTO increased after a high-fat diet
4	Claussnitzer (2015) [27]	Cross sectional	100 healthy Europeans	IRX3 and IRX5 expression	FTO polymorphism rs1421085, which has an effect on obesity, can double the expression of IRX3 and IRX5 genes during the distinction of primary adipocytes
5	Heffernan (2017) [24]	Cross- sectional	1089 athletes	expression IRX3	Those athletes with allele T for FTO have lower expression for IRX3