2D:4D finger length ratio and skeletal biomarker of biological aging

The aim of this population-based study was to evaluate the association between the index to ring (2D:4D) finger length ratio and the osseographic score (OSS), the skeletal biomarker of biological aging. A sample included 802 males and 738 females who had participated in a Chuvashian skeletal aging study. Age, sex, basic demographics, anthropometric data and X-rays of both hands were collected. Each hand was visually classified on X-ray as either Type 1 - index finger was longer than ring finger; Type 2 - equal; or Type 3 - shorter than the ring finger. OSS is a skeletal biomarker that comprises osteoporotic and osteoarthritic changes observable on a hands X-ray. The mean age of males in the studies sample was 46.98 ± 17.10 and mean age females was 48.65 ± 16.62. OSS showed significant association with age (r = 0.886, p < 0.001), body mass index (BMI) (r-0.253, p < 0.001) and sex (F = 13.771, p < 0.001). Results of one-way ANCOVA for finger length ratio types of right hand showed a significant difference in OSS (d.f. = 2, F = 7.569, p = 0.001), after adjustment for age, sex, and BMI. The posthoc comparison showed that individuals with Type 3 (2D < 4D) ratio showed significantly higher OSS scores that ones with Type 1 (p = 0.012) and Type 2 (p = 0.003). In an analysis of finger length ratio types of left hand also a significant difference in OSS was found (d.f. = 2, F = 3.290, p = 0.038). The posthoc comparison showed that individuals with Type 3 (2D < 4D) ratio showed significantly higher OSS scores that ones with Type 2 (p = 0.33) ratio. Finger length ratio is associated with an OSS, a skeletal biomarker of biological aging. Individuals with Type 3 finger length pattern showed significantly higher OSS that ones with Type 1 and Type 2.