Decreased second to fourth digit ratios in female multiple sclerosis patients

Sex-related differences in multiple sclerosis (MS) suggest a possible role of prenatal sex hormones in the pathogenesis. The aim of this study was to investigate whether the 2D:4D ratio, considered a predictor of prenatal hormonal exposure, in MS patients differ from that in healthy controls.

Two hundred MS patients and one hundred seventy healthy control subjects with similar age and sex distribution enrolled. All participants were right-handed. The right hands of all participants were scanned using a digital scanner. Measurements of second and fourth digit lengths were made from digital scans. The 2D:4D ratio was calculated by dividing the length of the second digit by the length of the fourth digit.

A total of 171 MS patients' and 159 healthy controls' digit scans included in the study. The MS group consisted of 94 females (mean age 38.32 ± 10.5) and 77 males (mean age 42.06 ± 11.8) and the control group of 86 females (mean age 40.24 ± 9.7) and 73 males (mean age 38.49 ± 11.6). 2D:4D ratios of female MS patients were significantly lower than those of healthy females (p=0.004). Although 2D:4D ratios of male patients with MS were lower than those of healthy males, this difference was not statistically significant (p=0.33). There was no significant correlation between the 2D:4D ratio, EDSS levels or duration of the disease in male or female MS patients (p<0.05).

Although our results suggest that a prenatal hormonal balance in favor of androgenic activity may be a risk factor for MS, complex factors mediating the actions of sex hormones on target cells should always be considered when evaluating the effects of sex hormones.