Low Ratio of Index to Ring Finger Length Tied to ALS

Finger length ratio lower in individuals with amyotrophic lateral sclerosis compared to controls

FRIDAY, May 13 (HealthDay News) -- A low ratio of index to ring finger length (2D:4D ratio), which is a surrogate marker for prenatal testosterone levels in both men and women, is found in individuals with amyotrophic lateral sclerosis (ALS), according to a study published in the June issue of the Journal of Neurology, Neurosurgery & Psychiatry.

Umesh Vivekananda, from King's College London School of Medicine, and colleagues investigated the relationship between prenatal testosterone levels measured by the 2D:4D ratio and development of ALS. A total of 47 patients and 63 unrelated control individuals attending a specialist tertiary referral center for ALS were included in the analysis. Hands were photographed with a digital camera, finger lengths were measured by four independent scorers, and the average 2D:4D ratio was derived.

The investigators found that the 2D:4D ratio was significantly lower for people with ALS than for controls after controlling for differences in sex ratio between the groups.

"Patients with ALS have a lower 2D:4D ratio, consistent with higher prenatal circulating levels of testosterone, and possibly a prenatal influence of testosterone on motor-neuron vulnerability in later life," the authors write.

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