Can the Second and Fourth Finger (2D: 4D) Ratio Guide Physicians in Choosing Internal Medicine or Surgical Branch? / ¿Puede la proporción del Segundo y Cuarto Dedo (2D: 4D) Guiar a los Médicos en la Elección de Medicina Interna o Rama Quirúrgica?

SUMMARY: This study investigates the relationship between the second and fourth finger ratio (2D:4D), physicians' propensity to choose an internal or surgical branch, and sex differences. On a voluntary basis, 177 physicians working in Elazig, 122 men and 55 women were enrolled in the study. Their hands were measured for 2D and 4D lengths, and the 2D:4D ratio was computed. In female doctors, the left hand's 2D:4D ratio is 1.01, compared to the right hand's 1.00. Male doctors' right 2D:4D ratio is 0.99, while their left 2D:4D ratio is 1.00. Male physicians' 2D:4D ratios were different from those of men in the general population, whereas female physicians' 2D:4D ratios were comparable to those of women in the general population. As a result, this study was the first to examine the relationship between the ratio of the second and fourth fingers (2D:4D), physicians' tendency to choose an internal medicine or surgical branch, and sex differences. While the 2D:4D ratio was higher than 0.98 in all physicians, it was low in women who disliked their profession and branch. Since there aren't many studies on this subject, data from in-depth studies that will be conducted in the future will help physicians who choose internal medicine and surgery make more informed decisions.

Este estudio investiga la relación entre la proporción de los dedos segundo y cuarto (2D:4D), la propensión de los médicos a elegir una rama interna o quirúrgica y las diferencias de género. De forma voluntaria, se inscribieron en el estudio 177 médicos que trabajaban en Elazig, 122 hombres y 55 mujeres. Sus manos se midieron en longitudes 2D y 4D, y se calculó la relación 2D:4D. En las médicos mujeres, la relación 2D:4D de la mano izquierda es 1,01, en comparación con 1,00 de la mano derecha. La relación 2D:4D derecha de los médicos hombres fue 0,99, mientras que la relación 2D:4D izquierda fye 1,00. Las proporciones 2D:4D de los médicos hombres fueron diferentes de las de los hombres en la población general, mientras que las proporciones 2D:4D de las mujeres médicas fueron comparables a las de las mujeres en la población general. Como resultado, este estudio fue el primero en examinar la relación entre la proporción del segundo y cuarto dedo (2D:4D), la tendencia de los médicos a elegir una rama de medicina interna o quirúrgica y las diferencias de sexo. Mientras que la relación 2D:4D fue superior a 0,98 en todos los médicos, fue baja en las mujeres que no les gustaba su profesión y rama. Dado que no hay muchos estudios sobre este tema, los datos de estudios en profundidad que se realizarán en el futuro ayudarán a los médicos que eligen medicina interna y cirugía a tomar decisiones más informadas.

Is digit ratio (2D:4D) different between sexual and non-sexual offenders, and non-offending men: study of a Colombian sample / Existen diferencias en la ratio 2D:4D entre delincuentes sexuales y no sexuales, y hombres no delincuentes? Un estudio en una muestra colombiana

Abstract One research line in criminal behavior studies 2D:4D ratio as predictor of aggression and violent behavior has been established, given that there are sexually dimorphic behaviors associated with the influence of testosterone on brain organization. However, results have been mixed. The aim of this study was to explore the differences in the 2D:4D ratio among offending and non-offending Colombian men in four groups (N = 139). A comparative study was conducted with three groups of offenders sentenced in a Colombian penitentiary: (1) sexual offenders against children (n = 34), (2) sexual offenders against adult women (n = 31), and (3) non-sexual violent offenders (n = 26); as well as one group (4) men with no criminal record (n = 48). The 2D:4D ratio was measured using the hand scanning technique and three digital measurements were analyzed with the Autometric software: right hand ratio, left hand ratio, and difference between the right and left hand ratios (Dr - Iz). Although, in all groups, right-digit ratio was lower that left-digit ratio (negative Dr-l ratio) and, in non-offending men this difference was not significant, no strong significant differences were found between groups in any measure of 2D:4D ratio used (right hand, left hand or Dr−l). The results support the idea that these associations are too weak to consider them predictors of sexual or non-sexual criminal behavior. The risk factors determining sexual or non-sexual criminal behavior, seems to go beyond intra-uterine effects and involve complex interactions between heritability, epigenetics, and pre-natal and post-natal life events.

Resumen Una de las líneas de investigación de la conducta criminal estudia la relación 2D:4D como predictor de agresión y comportamiento violento, dada la conexión de este marcador biológico con la influencia de la testosterona en la organización del cerebro y los comportamientos sexualmente dimórficos más prevalentes en hombres. Los resultados han sido mixtos y, en general, se han encontrado tamaños de efecto débiles, aunque significativos, en la relación entre proporción 2D:4D y el comportamiento agresivo, con escasos estudios comparativos y con muestras forenses. El objetivo de este estudio fue explorar las diferencias en la relación 2D:4D entre hombres colombianos (N = 139) con y sin delitos en cuatro grupos. Para ello, .e realizó un estudio comparativo con tres grupos de delincuentes condenados en una cárcel de Colombia: (1) agresores sexuales de menores (n = 34); (2) agresores sexuales de mujeres adultas (n = 31); (3) delincuentes violentos no sexuales (n = 26), y uno de (4) hombres sin antecedentes delictivos (n = 48). Se midió la proporción 2D:4D usando la técnica de escaneo de las manos y se analizaron tres medidas digitales con el software Autometric: proporción de la mano derecha, mano izquierda y diferencia entre la proporción de las manos derecha e izquierda (Dr - Iz). Se encontraron diferencias significativas entre la diferencia de la proporción Dr-Iz en todos los grupos, en la que la 2D:4D de la mano derecha fue menor que la de la mano izquierda en todos los grupos. Sólo en los hombres sin antecedentes delictivos esta diferencia no fue significativa. Para evaluar las diferencias grupales en las relaciones 2D:4D, se ajustaron modelos tipo a ANOVA unidireccional con un solo grupo como predictor, seguidos de contrastes de Helmert para comparar las diferencias entre todos los grupos. El grupo predijo sólo la diferencia de las proporciones Dr - Iz, pero no las proporciones de la mano derecha o izquierda por separado. El grupo de hombres sin antecedentes delictivos, mostró una proporción 2D:4D de la mano izquierda significativamente menor (masculinizada) y una menor diferencia (más cercana a cero) entre las proporciones Dr-Iz comparado con los grupos de delincuentes. Sin embargo, los contrastes con cada grupo, mostraron que la diferencia sólo fue significativa con el grupo de delincuentes violentos no sexuales, pero no con los grupos de agresores sexuales. Se concluyó que no hubo diferencias significativas importantes y concluyentes entre los grupos en ninguna medida de la proporción 2D:4D utilizada (mano derecha, mano izquierda o Dr − Iz). Estos resultados respaldan la idea de que estas asociaciones son demasiado débiles para considerarlas predictores de conductas criminales sexuales o no sexuales. Los factores de riesgo que determinan el comportamiento delictivo sexual o no sexual parecen ir más allá de los efectos intrauterinos reflejados por el biomarcador 2D:4D y, posiblemente, involucrar interacciones complejas entre heredabilidad, epigenética y eventos de la vida prenatal y postnatal. Si la relación 2D:4D es un marcador indirecto válido y confiable de androgenización prenatal, no es algo que se pueda discutir con los datos aquí obtenidos. Sin embargo, si tiene más que un simple efecto detectado por casualidad en el comportamiento delictivo, esto también debería explorarse más a fondo no sólo en la mano derecha, como la mayoría de la investigación disponible lo ha hecho, sino en la mano izquierda y en la diferencia entre las proporciones 2D:4D Dr-Iz, para evaluar si su poder explicativo se mantiene bajo como hasta ahora o incluso inexistente.

Asociación entre el cociente del segundo y cuarto dedo y el riesgo de cáncer de próstata: Un estudio de casos y controles en población mediterránea / Second to Fourth Digit Ratio and Prostate Cancer Risk: A Case-control Study in Mediterranean Population

Objetivo Evaluar la asociación entre el cociente de los dedos segundo y cuarto (2D:4D), como un biomarcador de la exposición prenatal a andrógenos, y la presencia de cáncer de próstata (CaP). Métodos Estudio de casos y controles con 260 hombres que consultaron en el Servicio de Urología del Hospital General Universitario Reina Sofía (Murcia, España). Los casos (n = 125) fueron pacientes diagnosticados de CaP por anatomía patológica a los que se les realizó una prostatectomía radical. Los controles (n = 135) fueron pacientes que consultaron en Urología por otro motivo y que no mostraron signos ni síntomas de patología prostática. La longitud del 2D y 4D de la mano derecha fue medida mediante un pie de rey digital y se calculó el cociente entre ambos (2D:4D). Para los análisis estadísticos se utilizaron modelos de regresión logística obteniendo Odds ratios (OR) crudas y ajustadas e intervalos de confianza al 95%. Resultados Los casos presentaron un cociente 2D:4D significativamente menor que los controles. El cociente 2D:4D se relacionó significativamente con la presencia de CaP. Tras el ajuste multivariante, se observó que los varones que se encontraban en el primer tercil de distribución del cociente 2D:4D, presentaban casi el doble de riesgo de padecer CaP (OR 1,9: IC 95% 1,1­4,0; P-valor = 0,040) en comparación con los varones que se encontraban en el segundo y tercer tercil. Conclusiones Una mayor exposición prenatal a andrógenos, reflejada por un cociente 2D:4D menor, podría estar asociado con riesgo aumentado de padecer CaP, pero más estudios son necesarios para corroborar esos hallazgos.

Objective To evaluate the association between second to fourth digit (2D:4D) ratio, as a biomarker of prenatal androgen exposure, and the presence of prostate cancer (PCa). Methods This was a case-control study of 260 men attending a Department of Urology in a Murcia Region hospital (Spain). Cases (n = 125) were patients who underwent radical prostatectomy due to PCa and were diagnosed by specimen's histopathology. Controls (n = 135) were patients who showed no signs or symptoms of prostate disease. The length of 2D and 4D of the right hand was measured two times using a digital caliper, and the ratio calculated (2D:4D). Unconditional multiple logistic regressions [crude and adjusted Odds ratios (OR) and 95% confidence intervals (CI)] were performed to evaluate associations between the 2D:4D ratio and presence of PCa. Results Cases showed significantly lower 2D:4D ratios than controls. 2D:4D ratios were significantly associated with the presence of PCa. After controlling for important covariates, men in the first tertile of the 2D:4D ratio distribution, compared with the second and third tertile, were almost two-times [OR 1.9 (95% CI 1.1­4.0; P-value = 0.040] more likely to have PCa. Conclusions A higher prenatal androgen exposure, indicated by lower 2D:4D ratios, might be associated with higher PCa risk, but further research is needed to confirm these findings in other male populations.

Investigation of second to fourth finger length ratio (2D:4D) in patients with bipolar disorder

Objective: The etiology of bipolar disorder has yet to be fully elucidated, but differences in sex hormones have been suggested to play a role in its pathogenesis. An easily assessed marker of prenatal androgen exposure is the second-to-fourth-digit ratio (2D:4D) of the hand. In this study, we aimed to compare the 2D:4D ratio of patients with bipolar disorder to that of healthy controls. Methods: Seventy patients with bipolar disorder and 70 healthy controls, matched for age and sex, were included in the study. Finger lengths were measured from the palmar digital crease to the tip using a digital vernier caliper. Results: Patients with bipolar disorder had considerably higher right-hand 2D:4D ratios compared to controls. Both the right and left 2D:4D ratios of male patients were significantly greater than those of males in the control group. Female patients showed no differences in right or left 2D:4D ratio compared to healthy controls. Conclusion: These findings suggest that a high 2D:4D digit ratio of right hand is associated with the presence of bipolar disorder in males. Further large-scale, prospective studies are needed to explain the validity of this marker and its relationship with bipolar disorder.

Relationships between the 2D: 4D digit ratio, waist circumference, hand preferences, weight, height, waist-to-height ratio and BMI in a Turkish population / Relaciones entre el promedio de dígitos 2D: 4D, circunferencia de cintura, preferencias de mano, peso, altura, relación de cintura a altura e IMC en una población de turquía

The 2D:4D is thought as a biomarker for prenatal androgen exposure. Some studies have reported a significant difference between the sexes. Earlier studies reported variations in different ethnic and geographic groups. 2D:4D is related to several medical conditions including cardiovascular diseases (CVD) and metabolic syndrome (MetS). The present study investigated the relationships between hand preference, ratio of the index finger (2nd digit: 2D) and ring finger (4th digit: 4D) lengths (2D:4D), height, waist-to-height ratio (WHtR), waist circumference (WC) and weight, body mass index (BMI) in a Turkish population. The study comprised 118 healthy subjects (68 males and 50 females). 2D and 4D finger lengths and some anthropometric traits (height, weight, WC) were measured. The BMI and WHtR were calculated. Hand preference was determined by using a questionnaire (Edinburgh handedness inventory). Geschwind scores were calculated to evaluate the degree of hand preference. The mean age was 26.74 (female 27.86, male 25.89). The right hand 2D:4D was found significantly lower in males (0.9797) than in females (0.9922) (p< 0.001), but the left hand 2D:4D was insignificant. Significant correlations (negative) were observed between the 2D:4D (both left and right) and WHtR; the 2D:4D ratio (both left and right) and WC in males. However, in females, these correlations were insignificant. The R2D:4D was sexually dimorphic in a Turkish population. There were significant differences between strong right (SR) and weak left (WL) in terms of the R2D:4D. However only 5 subject's hand preference was found WL. Therefore, further studies are needed to determine the relationships between hand preference and R2D:4D in Turkish population. Further studies are needed to determine whether a larger sample population alters these possible associations between the ratio of 2D:4D and other investigated traits in a Turkish population.

El 2D:4D está pensado como un biomarcador para la exposición prenatal de andrógenos. Algunos estudios han reportado una diferencia significativa entre sexos. Estudios anteriores informaron variaciones en diferentes grupos étnicos y geográficos. 2D:4D está relacionado con varias afecciones médicas que incluyen enfermedades cardiovasculares (ECV) y síndrome metabólico (MetS). El presente estudio investigó las relaciones entre la preferencia de la mano, la proporción del dedo índice (2º dígito: 2D) y el dedo anular (4º dígito: 4D), longitudes (2D:4D), altura, relación cintura-altura (WHtR), circunferencia de cintura y peso (WC), e índice de masa corporal (IMC), en una población de Turquía. El estudio incluyó 118 sujetos sanos (68 hombres y 50 mujeres). Se midieron longitudes de dedos 2D y 4D y algunos rasgos antropométricos (altura, peso, WC). Se calcularon el IMC y el WHtR. La preferencia de la mano se determinó mediante el uso de una escala (Edinburgh Handedness Inventory). Las puntuaciones de Geschwind se calcularon para evaluar el grado de preferencia de la mano. La edad media fue de 26,74 años (femenino 27,86; masculino 25,89). La mano derecha 2D: 4D se encontró significativamente más baja en los hombres (0,9797) que en las mujeres (0,9922) (p <0,001), pero la mano izquierda 2D: 4D fue no significante. Se observaron correlaciones significativas (negativas) entre la 2D: 4D (izquierda y derecha) y WHtR y la relación 2D: 4D (izquierda y derecha) y WC en hombres. Sin embargo, en las mujeres, estas correlaciones fueron no significantes. El R2D: 4D fue sexualmente dimorfo en una población de Turquía. Hubo diferencias significativas entre la mano derecha fuerte (SR) y la mano izquierda débil (WL) en términos de R2D: 4D. Sin embargo, sólo se encontraron 5 preferencias de mano en el sujeto con WL. Por lo tanto, se necesitan más estudios para determinar las relaciones entre la preferencia de mano y R2D: 4D en la población de Turquía. Se necesitan más estudios para determinar si una muestra mayor altera estas posibles asociaciones entre la proporción de 2D: 4D y otros rasgos investigados en una población de Turquía.

2nd to 4th Digit Ratio (2D:4D) – Is It a Marker for Dyslexia?

Background: Specific learning disorder in general called as dyslexia is a neuro developmental disorder,which occurs more commonly in males (Male:Female ratio is 4:1), there are evidence to suggest role ofprenatal gonadal hormone exposure in neurodevelopment. However, studies on association between 2nd to4th digit ratio and dyslexia are mixed. Objective: To compare the 2nd and 4th digit ratio (2D:4D) of bothhands between children with dyslexia and children without dyslexia.Methodology: A case control study, recruited 30 children with dyslexia and 30 age and education matchednormal controls, after getting informed consent from their parents. Collected socio demographic details,applied CARS, Schonell’s reading and spelling test, followed by detailed evaluation by psychiatrist andclinical psychologist, including psychological testing to confirm the diagnosis of dyslexia. The digit lengthof index and ring finger on both hands of all children were measured using Vernier Calliper by direct method.Results: In both the hands 2D:4D ratio was more in children with dyslexia than normal children, but thedifference was not significant (p – 0.146). Analysis of only male samples showed digit ratio is higher indyslexic children than normal children; which were significant (p – 0.03).Conclusion: Our study does not support an association between digit ratios and dyslexia; however, trendtowards higher ratio in dyslexia especially in male children are interesting and needs further exploration.Need more studies in this area to form a definite conclusion.

Cross Sectional Study of Second and Fourth Digit Ratio with Physical Attributes in South Indian Population.

Background: Study of the index (2D) and ring (4D) digit ratios and their association with some physical characteristics of South Indian Population was done to determine the values of 2D:4D digit ratios and their association with other anthropometric variables. Materials and Methods: 160 adults (80 males and 80 females) between ages of 18 years and above were randomly selected with exclusion of those with hand deformities. The digit lengths were measured from the basal crease to the tips using vernier calipers. The 2D:4D ratios were determined for each subject while height and weight were used to calculate the body mass index and data analyzed. Results: The results showed significant difference in 2D:4D ratio between males and females. (p<0.001). Mean height of males exceeded the mean height of females and the mean weight of males exceeded the mean weight of females .Mean BMI of males also exceeded that of females. There was a positive correlation between the second digit length and Height and weight in males and females both on right and left sides. There was also a significant correlation weight and second digit length in males.The 2D:4D ratio for both left and right hand did not show any positive correlation with height, weight or BMI of an individual from people of South India. Conclusion: The results show a positive correlation between the digit lengths and height in both males and females and between weight and second digit length in case of males but the 2D:4D digit ratio had no relationship to height ,weight or BMI.The analysis also demonstrated that the males have greater 2D:4D ratio compared to females. The results of the study can be of importance in the field of forensic anthropology.

Digit Ratio (2d4d) and Performance in Indian Swimmers.

It has been suggested that achievement in sports is correlated with a putative measure of prenatal testosterone the 2nd to 4th digit ratio (2D: 4D). It has been shown that digit ratio (2D: 4D) is negatively associated with prenatal testosterone, and it is also negatively associated with ability in sports. This study examined associations between 2D: 4D and performance of both male and female National level Indian swimmers. Age matched non-sports personnel formed the control. Lengths of second and fourth digits were measured after scanning both hands and their ratio calculated. Our results show lower 2D:4D values in males compared to females (P<0.05). Among male, but not female, swimmers had significantly (P<0.05) lower 2D: 4D ratio. Low 2D: 4D in male swimmers suggests they are more prenatally programmed via long-lasting extra genital effects of testosterone. 2D: 4D ratio could be used to identify young sports personnel who have potential to reach high levels of performance.

A Study of the Relationships between the Ratio of 2nd to 4th Digit Length and Cerebral Laterality

OBJECTIVES: Cerebral laterality is thought to be an important marker for neurodevelopment. Prenatal testosterone could influence both cerebral laterality and 2nd to 4th finger length ratio(2D:4D). EEG coherence and 2D:4D were examined to investigate the relationship between prenatal testosterone level and cerebral laterality. METHODS: EEG was recorded in 24 healthy subjects in the eyes closed resting state. Differences in 2D:4D finger ratio were used to discriminate "masculine finger type" and "feminine finger type" groups. The 2D:4D ratio was lower and greater than one for the "masculine finger type" group and "feminine finger type" group, respectively. We used coherence analysis to estimate the cortical functional connectivity. RESULTS: There were statistically meaningful relationships among cerebral functional connectivity, sex and finger ratio. Man and masculine finger type group showed higher intra-hemispheric coherence than those of woman and feminine finger type group. Woman and feminine finger type group showed higher inter-hemispheric coherence than those of man and masculine finger type group. CONCLUSIONS: These results imply that prenatal testosterone might act as important determinants of cerebral laterality. Further examination of the relationship between 2D:4D and EEG coherence in schizophrenia could give some clues for the neurodevelopmental hypothesis of schizophrenia genesis.

The Correlation between 2nd to 4th Digit Length Ratio and Characteristics of Temperament and Character in University Students

OBJECTIVES: The 2nd to 4th digit length(2D:4D) ratio reflects the amount of exposure and sensitivity to the prenatal sex hormone and it is considered to be the most convenient and useful way to understand the influence of sex hormone in the determination of human behavioral traits. This study was carried out to find the correlation between the 2D:4D ratio and characteristics of temperament and character in Korean university students. We assumed that 2D:4D ratio would show a strong correlation with temperament which is defined to be an inclination of an automatical emotional response to a stimulus. METHODS: Participants were 104 university students who completed 2 self-report measures:Temperament and Character Inventory(TCI), Temperament Test. We examined the 2D:4D ratio of each subject by measuring the lengths of the 2nd and 4th fingers using a photocopy measurement. We performed statistical analyses using correlation test and t-test to examine the relationship between 2D:4D ratio and psychological characteristics. RESULTS: We found out the typical sex difference in 2D:4D ratio. Women had significantly higher 2D:4D ratio than men. TCI-Character factor(TCI-C) didn't show any significant correlation with the 2D:4D ratio. TCI-Tempterament factor(TCI-T) and the item of Temperament Test showed a significant correlation with the 2D:4D ratio. In correlation analysis of the total group including all women and men, the 2D:4D ratio showed a significant positive correlation in a subscale(shyness with stranger) of harm avoidance scales in TCI-T. In correlation analysis of women's group, the 2D:4D ratio showed a significant positive correlation in two subscales( fear of uncertainty) and[shyness to stranger] of harm avoidance scales in TCI-T. In correlation analysis of men's group, the 2D:4D ratio showed a significant negative correlation with a sanguine temperament item of the Temperament Test. CONCLUSION: The results suggest that the amount of exposure to sex hormone in the prenatal period seems to have an impact on the determination of temperament and characteristics.