Second-to-fourth digit ratio and seborrheic dermatitis in males: a cross-sectional study*

Abstract

Background Seborrheic dermatitis is a common disease characterized by the erythematous plaques with oily-yellow desquamation. Increased sebaceous gland activity by androgenic hormones has played a role in the etiology of the disease. The second-to-fourth digit (2D:4D) ratio is thought to be a marker of prenatal androgen exposure. Objectives To investigate the association between 2D:4D ratios and seborrheic dermatitis in a male population. Methods Healthy male controls and patients with seborrheic dermatitis were included in this study. One hundred seborrheic dermatitis patients and 120 healthy controls, aged 17-59, were enrolled. A digital Vernier caliper was used to measure the finger lengths. Seborrheic dermatitis severity was assessed using the Seborrheic Dermatitis Area and Severity Index (SDASI). Results The 2D:4D ratios of the patients ( = 0.977) were significantly lower than those of the controls ( = 1.050) for right hands (t = 6.948; p = 0.000; > 0.05). No similar relationship was found between the 2D:4D ratio for left hands (t = 0.901; p = 0.368; > 0.05). Seborrheic dermatitis severity was negatively correlated with 2D:4D ratios of right hands (r = -0.391; p = 0.000-0.05). Study limitations One of the main limitations of this study was the small sample, which got a head of us from acquiring certain findings about the 2D:4D ratio and seborrheic dermatitis. The other limitation is that the patient selection did not reflect the general population, as a single clinic was studied. Conclusion To the authors' knowledge, this is the first study examining the relationship between 2D:4D ratios and seborrheic dermatitis. The result of this study may indicate a line of investigation and can support the theory of prenatal androgen exposure.

Is prenatal testosterone‐estrogen balance associated with psoriasis?

“…The 2D:4D ratio positively correlates with IL-6; the change in balance in favor of prenatal estrogen can be used for screening low-grade inflammation after birth. 23 Female patients with psoriasis had a lower 2D:4D ratio compared with females in the control group in our study, suggesting that the disruption of the fetal estrogen-testosterone balance against estrogen is a predisposing factor for the development of psoriasis in females; however, the results were not statistically significant. In this study, male patients with psoriasis had a higher 2D:4D ratio for both hands compared with males in the control group.…”

“…Estrogen deficiency in females and testosterone deficiency and high estrogen levels in males cause exacerbation of psoriasis. The 2D:4D ratio positively correlates with IL‐6; the change in balance in favor of prenatal estrogen can be used for screening low‐grade inflammation after birth 23 . Female patients with psoriasis had a lower 2D:4D ratio compared with females in the control group in our study, suggesting that the disruption of the fetal estrogen‐testosterone balance against estrogen is a predisposing factor for the development of psoriasis in females; however, the results were not statistically significant.…”

Cutaneous Malassezia: Commensal, Pathogen, or Protector?

“…Triggering factors include stress and cold, dry weather (Gary, 2013;Borda and Wikramanayake, 2015). The prevalence is higher in men than women, potentially due to hormonal influence by androgens (Islamoglu, 2019). However, this may also be a result of differences in grooming practices between genders.…”

The Evaluation of 2D/4D Finger Ratios in Seborrheic Dermatitis Cases

“…In the current literature, only one study found that the relationship between seborrheic dermatitis and 2D: 4D finger length ratios were evaluated, in the study, only male cases were taken (10). In the study, in male seborrheic dermatitis cases, 2D: 4D finger length ratios in the right hand were significantly lower than the control group (10). In our findings, the rate of lefthand 2D: 4D fingers was found to statistically significantly lower only in patients with male seborrheic dermatitis compared to the control group.…”