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Digit ratio suggests link to prenatal hormone levels in patients with SLE
Variation in the ratio between the second and fourth finger could suggest that patients with systemic lupus erythematosus may have been exposed to high prenatal testosterone and low prenatal estrogen, according to researchers at the Juntendo University Faculty of Medicine.
The researchers recruited 50 male and 50 female ambulatory patients with systemic lupus erythematosus (SLE) and 100 healthy age- and sex-matched controls with no family history of autoimmune diseases.
Images of both hands of all participants were collected using a digital camera, and the second-to-fourth digit ratio (2D4D) was measured using the measurement tool in Adobe Photoshop three times and averaged. Intraclass correlation showed high reliability and similarity in the measurements.
As the researchers expected, the 2D4D ratio among healthy women was higher than that found in healthy men in both the right and left hands. However, the 2D4D ratio of the right hand in men with SLE was significantly lower than in healthy men and healthy women, but no difference was seen between left hands of healthy men and men with SLE.
The 2D4D ratio in women with SLE was significantly lower than the ratio in healthy women in both hands, according to the researchers. After adjusting for sex, the 2D4D ratios were significantly lower in all patients with SLE compared with healthy participants. – by Shirley Pulawski
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