The Ratio of 2nd to 4th Digit Length in Korean Alcohol-dependent Patients.
OBJECTIVE
The ratio of 2nd to 4th digit length (2D:4D) is a sexually dimorphic trait. Men have a relatively shorter second digit than fourth digit. This ratio is thought to be influenced by higher prenatal testosterone level or greater sensitivity to androgen. The purpose of this study is to investigate the relationship between alcohol dependence and 2D:4D in a Korean sample and whether 2D:4D can be a biologic marker in alcohol dependence.


METHODS
In this study, we recruited 87 male patients with alcohol dependence from the alcohol center of one psychiatric hospital and 52 healthy male volunteers who were all employees in the same hospital as controls. We captured images of the right and left hands of patients and controls using a scanner and extracted data with a graphics program. We measured the 2D:4D of each hand and compared the alcohol dependence group with the control group. We analyzed these ratios using an independent-samples t-test.


RESULTS
The mean 2D:4D of patients was 0.934 (right hand) and 0.942 (left hand), while the mean 2D:4D of controls was 0.956 (right hand) and 0.958 (left hand). Values for both hands were significantly lower for patients than controls (p<0.001, right hand; p=0.004, left hand).


CONCLUSIONS
Patients who are alcohol dependent have a significantly lower 2D:4D than controls, similar to the results of previous studies, which suggest that a higher prenatal testosterone level in the gonadal period is related to alcoholism. Furthermore, 2D:4D is a possible predictive marker of alcohol dependence.
Department of Psychiatry, Korea University Ansan Hospital, Ansan, Korea.
Changwoo
C
Han
Department of Psychiatry, Myongji Hospital, College of Medicine, Seonam University, Goyang, Korea.
Hwallip
H
Bae
Yong-In Mental Hospital, Yongin, Korea.
Yu-Sang
YS
Lee
Department of Psychiatry, Korea University Ansan Hospital, Ansan, Korea.
Sung-Doo
SD
Won
Department of Psychiatry, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Dai Jin
DJ
Kim
Alcohol dependence; Biological markers; Finger length; Genetic epigenesis