Digit ratios and relation to myocardial infarction in Greek men and women

Abstract

Background: Digit ratios, such as the second to fourth digit ratio (2D:4D), are biometric markers that are influenced by estrogen and testosterone concentrations in utero and are determined genetically by HOX genes (homeodomain-containing homeotic genes). Sex steroids also play a crucial role in the occurrence of myocardial infarction (MI), which is considered to be gender dependent and related to testosterone. Additionally, first-trimester exposure to excess levels of estrogens and progesterone has been linked to cardiovascular anomalies.

Objective: The aim of this work was to study digit ratios in a Greek population and assess their clinical importance as markers of predisposition to MI.

Methods: Two samples were used: a group of Greek men and women hospitalized with MI, and a control group of healthy Greek men and women of the same age. Finger lengths were measured twice for both hands using electronic calipers. In the results, digits were designated as 2D (second digit), 3D (third digit), 4D (fourth digit), and 5D (fifth digit).

Results: A total of 50 Greek men and 50 Greek women with MI were recruited (mean [SD] age, 69.3 [11.2] years for men; 69.7 [11.0] years for women). The control group consisted of 40 healthy Greek men and 40 healthy Greek women (mean age, 68.0 [11.8] years for men; 66.8 [10.7] years for women). In the control group, 2D:4D, 2D:3D, and 2D:5D ratios were significantly higher in women than in men (2D:4D: right hand, P < 0.001; left hand, P = 0.002; 2D:3D: right hand, P < 0.001; left hand, P = 0.003; 2D:5D: right hand, P < 0.001; left hand, P < 0.05). The mean values of 2D:4D ratios appeared to increase in the following order: healthy men < men with MI < healthy women < women with MI, although this difference was not statistically significant. In men with MI, 2D:4D and 3D:4D ratios were significantly higher than the respective ratios in healthy men (2D:4D: right hand, P = 0.001; left hand, P < 0.05; 3D:4D: right hand, P < 0.05; left hand, P = 0.001), but no significant differences were observed in the ratios between women with MI and healthy women.

Conclusions: Digit ratios that include ring-finger length (ie, 4D) may be useful biomarkers for predisposition to MI in Greek men, but not in Greek women. Sexual dimorphism of digit ratios was present in both groups and was independent of the individuals' health status.