The second to fourth digit ratio in patients with congenital IGF-1 Deficiency

The relationship between the length of the second and fourth ring finger (2D:4D ratio) is a sexually dimorphic trait, higher in females than in males. It is established during early prenatal development under the influence of sex hormones, as demonstrated in numerous studies both in humans and in mice. The current study involves patients with congenital GH/IGF-1 deficiency, a population not yet investigated. The 2D:4D ratio was measured from hand x-rays and compared with normal hand x-rays taken from the Greulich & Pyle Atlas. The analyses of our results revealed that patients with congenital GH/IGF-1 deficiency show an identical 2D:4D ratio for both sexes, but a higher (more feminine) ratio than the normal population. These findings may be explained by a higher estrogen effect resulting from the absence of a functional GH-IGF-1 axis prenatally.