Table 5.

Confounding variables considered to cause the discrepancy of the relationships between β-adrenoceptor polymorphisms and phenotypes of hypertension and metabolic syndrome in obesity.

Variables [reference number]	Findings in the studies
Severity of obesity [16, 57, 62, 76, 95]	In lean subjects, β2-AR polymorphisms linked to obesity and obesity-related hypertension, but in obese subjects, β2- and β3-AR polymorphisms relate to obesity and obesity-related hypertension.
	Morbid obesity is linked with β3-AR polymorphisms, but overweight or mild obesity is not associated with those.
Gender differences [71]	Interaction between β1- and β2-AR polymorphisms with changes in BMI was observed in men only, while in women an interaction between β1- and β3-AR polymorphisms was observed in a longitudinal over a 24-year period large cohort study.
Ethnic difference [103, 104]	Distributions of β-AR polymorphisms are different in 8 different ethnic populations.
Haplotype [20, 58, 59, 105–107]	Functions expressed of β-AR polymorphisms are different due to the other β-AR polymorphisms.

AR: adrenoceptor; BMI: body mass index.