Table 2.

Main characteristics of the studies examining the relationship between leptin, adiponectin gene polymorphism and HCC

Author, Year, Country	Study design	Case/control	Number	Matching variables	SNP	Samples source	Genotyping methods	Frequency of case genotype	Frequency of control genotype	NOS score
Amer, 2017, Egypt	C	HCC/Healthy controls	150/100	age, sex and smoking rate	rs7799039 (leptin gene)	blood	PCR-RFLP technique	AA = 60; AG = 69; GG = 21; G allele =111; A allele =189	AA = 49; AG = 47; GG = 4; G allele =54; A allele =146	7
Zhang, 2018, China	C	HCC/Healthy controls	575/921	age and sex	rs7799039 (leptin gene)	blood	SNPscan™	AA = 295; AG = 221; GG = 59; G allele = 339; A allele =811	AA = 505; AG = 360; GG = 56; G allele = 472; A allele =1370	7
Cai, 2013 China	C	HCC/Healthy controls	200/200	age and sex	rs1501299 (adiponectin gene)	blood	DNA sequencing	TT = 12; TG = 60; GG = 128; G allele = 316; T allele =84	TT = 39; TG = 69; GG = 92; G allele = 253; T allele =147	8

C Case-control, SNP single-nucleotide polymorphisms, PCR-RFLP polymerase chain reaction-restriction fragment length polymorphism, NOS Newcastle-Ottawa Scale