Association between the digit ratio (2D:4D), handgrip strength, wrist ratio, and body fat distribution in women with different carpal tunnel syndrome severity.

BACKGROUND: To evaluate the relationship of the second to fourth digit ratio (2D:4D), a biomarker of prenatal sex hormone exposure, with wrist ratio (WR), wrist-palm ratio (WPR), body mass index (BMI), waist-hip ratio (WHR), and handgrip strength (HGS) in different carpal tunnel syndrome (CTS) severity. METHOD: This study involved 90 female participants (aged 18 to 83) with CTS. According to CTS severity, the participants were divided into four groups: normal, mild, moderate, and severe. All parameters of hand anthropometry and body fat distribution were measured, and the mean 2D:4D, WR, WPR, HGS, BMI, and WHR values were compared based on CTS severity. Data were collected with a visual analog scale (VAS) for pain and a Likert (LS) scale for numbness severity. RESULTS: The mean age, 2D:4D, WD, WW, WR, WPR, BMI, and HGS values showed a significant differences between CTS severity groups. We found that lower 2D:4D and higher WPR and BMI were associated with increased risk of CTS (AUC = 0.728) after removing the effect of age. Bilateral hands were affected in 38.9 % (70/180) of participants. Regression analysis showed that lower HGS can be used as independent variable for predicting the females having bilateral affected hands. The LS score was considerably higher in the severe and moderate groups. Also, the VAS score was significantly higher in the severe group. CONCLUSION: The findings of the study demonstrated an association between 2D:4D, WPR, and BMI among women, emphasizing the effect of intrauterine sex hormone exposure on late life CTS severity.

Understanding Covid-19: Digit ratios and duration of oxygen therapy in hospitalized Covid-19 patients.

BACKGROUND: Covid-19 severity shows a sex difference (males>females) and progressive hypoxia among the most seriously affected. Digit ratios are sexually dimorphic and may be negatively-related to prenatal (2nd-to-4th digits' ratio; 2D:4D) and pubertal (3rd-to-5th digits' ratio; 3D:5D) testosterone. Oxygen therapy is important in Covid-19 treatment and low 2D:4D is linked to efficient oxygen metabolism. We consider relationships between digit ratios and duration of oxygen treatment in hospitalized Covid-19 patients. METHODS: Digit lengths were measured from photographs of the patient's hands. Age, Sex, BMI, vaccination status and number of days of O2 treatment, were recorded. RESULTS: There were 100 (58 women) patients. Sex differences (males

Digit Ratio (2D:4D; Right-Left 2D:4D) and Multiple Phenotypes for Same-Sex Attraction: The BBC Internet Study Revisited.

Same-sex attraction may be linked to low prenatal androgen (in men) and high prenatal androgen (in women). Digit ratio (2D:4D) is thought to be a negative correlate of prenatal androgen and right-left 2D:4D (Dr-l) to reflect lateralized differences in sensitivity to prenatal androgen. Lower 2D:4D has been reported for lesbians compared to heterosexuals, but links to high 2D:4D in gay men are less clear. The largest study thus far (the BBC Internet study) found no significant difference between the 2D:4D of lesbians and heterosexual women but a higher 2D:4D in gay men compared to heterosexual men. Here we consider the possibility that low and high prenatal androgen is associated with same-sex attraction in men (n = 108,779) and women (n = 87,742), resulting in more than two phenotypes. We examined the associations between 2D:4D, Dr-l, and same-sex attraction scores in the BBC Internet study. In contrast to the earlier report, which considered sexual orientation in categories, there were positive linear associations in men (right and left 2D:4D, but not Dr-l) and negative linear associations in women (right 2D:4D and Dr-l, but not left 2D:4D). There were no curvilinear relationships for right and left 2D:4D. However, Dr-l showed a U-shaped association with same-sex attraction in men. Thus, (1) high prenatal androgen may be implicated in female homosexuality, while both low and high prenatal androgen may be implicated in male homosexuality, and (2) large side differences in sensitivity to androgen may be associated with elevated same-sex attraction in men.

Digit ratio and the femoral circumflex artery perforator: A sex-dependent association between the vascular system of the thigh and prenatal sex hormones?

BACKGROUND: The anterolateral thigh flap (ALTF) is a type of free flap which is commonly used in reconstructive surgery procedures and is based on the perforator from femoral circumflex artery. Some authors found that the location of the perforator differs between sexes. OBJECTIVE: To verify the influence of prenatal sex hormones (as measured by 2D:4D) on the morphology of the perforator of the descending branch of the femoral circumflex artery. METHODS: 88 participants (43 women) of a mean age of 28.5 years (SD 8.1 years) had the following measurements performed: height and weight; right and left-hand 2nd and 4th fingers' lengths; and distance from anterior superior iliac spine to the perforator from descending branch of lateral femoral circumflex artery related to the thigh length (right and left) (AP ratio). RESULTS: Right 2D:4D and Dr-l (right minus left 2D:4D) were dimorphic, similarly to AP ratio (right and left), which in women was significantly higher than in men. A significant correlation was found between right and left 2D:4D and location of the perforator of the left thigh in men. The higher right and left 2D:4D (more feminine) the higher the left AP ratio (more feminine). CONCLUSION: Our findings suggest that the location of perforator of femoral circumflex artery may be influenced by prenatal sex steroids such that low prenatal testosterone and high prenatal oestrogen are correlated to high AP (lower branching of the artery).

Patients with developmental dysplasia of the hip shows higher digit ratio (2D:4D).

BACKGROUND: Developmental dysplasia of the hip (DDH) encompasses a range of hip disorders, from dysplasia to dislocation. One key factor is sex, with women being four to eight times more susceptible to DDH than men. However, there have been no studies investigating the second-to-fourth digit ratio (2D:4D), a biomarker of prenatal sex steroid exposure, in DDH patients. This study aimed to explore whether there is an association between the 2D:4D ratio and DDH. METHODS: Digital calipers were used to measure the second and fourth finger lengths of 250 patients treated for DDH and 200 patients in the healthy control group between January 2020 and January 2023. The Mann-Whitney U test was used for non-normally distributed variables and two-way analysis of variance to assess differences in measurements between DDH patients based on sex, side, and the interaction of sex and side. The intraclass correlation coefficient (ICC) was used to assess measurement repeatability. RESULTS: The median (min-max) age was 10.00 (6-16) years in the DDH group, 12.00 (6-16) years in the control group, and 10 (6-16) years for the whole cohort. There was no significant difference in terms of age between the patient and control groups (p = 0.083). When comparing the DDH group with controls the former showed higher right 2D:4D and Δ2D:4D and these differences were significant in both males and females. Among the patients, controlling for side of dysplasia did not affect right 2D:4D, left 2D:4D or Δ2D:4D. CONCLUSION: There was a significant association between higher 2D:4D ratios (both right and left hands) and DDH in both men and women. This indicates that the 2D:4D ratio, a marker of intrauterine estrogen/testosterone balance, is associated with DDH.

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 2D:4D digit ratio related to avowed religion? A study among Mongolian young males from Ulaanbaatar.

BACKGROUND: The ratio of the second- (2D) to fourth (4D) digit lengths of hand (2D:4D) is a proxy marker of the relative testosterone and estrogen concentration during a relatively narrow period of fetal development that might affect behavioral and personality characteristics. AIM: To estimate the differences in 2D:4D between different religious groups among a sample of young adult males in Mongolia. METHODS: Two hundred and sixty-five Mongolian male students with mean age of 20.5 (SD = 1.7) years from different universities in Ulan Bator, were included in the study. Information on age, religious affiliation, marital status and parental education were obtained directly from each study participant. Digit lengths were measured from scanned images by using the ImageJ software 1.53 K. One-way analysis of variance was employed to evaluate whether they were significant differences in 2D:4D ratio between groups, along with Scheffe's post hoc comparison. RESULTS: Study participants significantly differed in 2D:4D across religion. Left 2D:4D, but not the right, showed a significant difference between religions, with Muslims exhibiting the highest 2D:4D mean and the lowest DR-L . CONCLUSION: Our study suggests that the 2D:4D ratio is related to the participants' religion. However, the distinctiveness of the Muslim students from study participants belonging to other religious groups in this study could also be related to ethnic differences, given that the students were Kazakhs. This is, to our knowledge, the only study looking at the relationship between the 2D:4D ratio and religious affiliation and, thus, further research is needed to confirm its results.

Direct and radiographic digit ratio (2D:4D) measurements of Tuvan children and adolescents from Southern Siberia: Sex differences and skeletal maturation.

BACKGROUND: In Mongolian-origin ethnic groups digit ratio (2D:4D; a proxy for prenatal sex-steroids) is sexually dimorphic (males < females), as reported for other ethnicities. Most studies measured 2D:4D from soft tissue (directly from the digits, or indirectly from hand scans), or from radiographs. Evidence on the correspondence of 2D:4D measurements from soft tissue with measurements from radiographic images is scarce and has not been reported for a Mongolian-origin sample. In addition, previous research has not considered relationships between 2D:4D and measures of skeletal maturity. AIM: To examine (i) associations between 2D:4D measured directly from the palms with those obtained from radiographic images of the same individuals in a sample of children and adolescents from the Tuvan population in Siberia (Russian Federation), and ii) associations between 2D:4D measurements with chronological and skeletal age. SUBJECTS AND METHODS: Participants were Tuvan boys and girls aged 7 to 18 years. 2D:4D of the right and left hand was measured from soft tissue (directly from the palm) and compared with radiographic images (left hand only). In addition to finger length 2D:4D, we examined 2D:4D of the phalanges from measurements of radiographs. Skeletal age was assessed using the Tanner-Whitehouse method. RESULTS: Sex differences (boys < girls) in measurements of 2D:4D from soft tissue and radiographs were found for total finger length and phalanges. In addition, 2D:4D measurements from radiographs correlated positively and significantly with those obtained from soft tissue. Sex predicted 2D:4D measurements from soft tissue and radiographs, but no effects of chronological/skeletal age and body height were detected. In girls (but not in boys), earlier skeletal maturity (relative to chronological age) was associated with higher 2D:4D in soft tissue measurements of both hands, radiographic 2D:4D, and 2D:4D of the proximal phalanges. CONCLUSION: Consistent with reports from other ethnic groups, 2D:4D in young Tuvans was sexually dimorphic, with boys having lower 2D:4D than girls. For girls, higher 2D:4D was found for participants whose skeletal age was more advanced than chronological age. This finding was obtained from direct soft tissue and indirect radiographic measurements. Age and body height were not associated with 2D:4D, which suggests differences in hormone developmental trajectories for 2D:4D and height.

Relationship of digit ratio with sexual steroid hormone receptor related genes - single nucleotide polymorphisms in a sample from Northern China.

BACKGROUND: Digit ratio, especially 2D:4D, is hypothesised as a potential biological marker of exposure to intrauterine sex hormones. The aim of this study was to investigate the association between 10 SNPs of sex steroid hormone receptor (SSHR) related genes and 2D:4D. SUBJECTS AND METHODS: 814 college students were randomly selected as research participants. After taking pictures of both hands of the participants, Image Pro Plus (IPP) software was used to measure 2D:4D. ESR1 (rs2228480 and rs3798758), ESR2 (rs944459, rs8006145, rs928554, and rs8018687), GPER1 (rs10269151 and rs12702047), and PGR (rs1042839 and rs500760) were genotyped using multiplex PCR. RESULTS: Females had significantly higher 2D:4D in both hands than male students (p < 0.05), and the R2D:4D of the Han population was significantly higher than that of the Hui population (p < 0.05). The number of females carrying the GPER1 G allele of rs12702047 was significantly higher than that of males (p < 0.05). The L2D:4D in males was significantly different in rs1042839, and the R2D:4D in the Han ethnicity was significantly different in rs3798758. Logistic regression analysis showed that rs12702047 was significantly associated with 2D:4D in both hands (p < 0.05). CONCLUSIONS: GPER1 rs12702047 may be involved in the formation of digit ratio by affecting phalanx development in the Chinese population.

Digit ratio (2D:4D) and its relationship to foetal and maternal sex steroids: A mini-review.

The challenges of terrestrial existence may mean that the early development of tetrapod limb traits is linked to the development of the urogenital system and sex steroids. One such limb trait is the sex-dependent ratio of the lengths of the 2nd and 4th digits (2D:4D). Direct evidence for the association between early sex steroids and offspring 2D:4D can be obtained by manipulating foetal sex hormones. However, this is not ethically permissible in humans. It is widely accepted that 2D:4D is a biomarker for early foetal sex hormones in tetrapods but the link in humans remains controversial. Here we review the evidence that (i) manipulation of sex steroids in early development leads to sex-dependent changes in 2D:4D throughout the tetrapods, and (ii) maternal sex steroids cross the placenta and thus are associated with offspring 2D:4D in both non-human and human animals. We suggest a research focus on associations between human maternal sex steroids and offspring 2D:4D to clarify the link between 2D:4D and early sex steroids. A protocol is proposed to examine the correlation between 1st-trimester maternal sex steroids and offspring 2D:4D. Such an association may explain the existence and medium effect size of the human sex difference in 2D:4D.

Systematical assessment of digit ratio in a female masculinization disease: polycystic ovary syndrome.

Background: In recent years, the right ratio of 2nd and 4th digit length (2D:4D) is regarded as an anatomical marker of prenatal testosterone exposure. Polycystic ovary syndrome (PCOS) is a female masculinized disease and is determined by prenatal testosterone exposure. Whether the ratio in the right hand of PCOS women is reduced or not compared with non-PCOS women is under debate. To further investigate the relationship between PCOS and digit ratio, we systematically measured all the digit ratios. Methods: We recruited 34 non-PCOS women, 116 PCOS women, and 40 men and systematically measured all the ratios of digit length (2D:3D, 2D:4D, 2D:5D, 3D:4D, 3D:5D, and 4D:5D) of right hands and left hands. Results: Left 2D:3D, 2D:4D, and 2D:5D in men were significantly lower than those in non-PCOS women. Significantly lower digit ratios of left 2D:3D and 2D:4D were observed in PCOS compared with non-PCOS women. In the subgroup analysis, the left ratio of digit length in 2D:3D and 2D:5D of the hyperandrogenism subgroup was lower than that of the non-hyperandrogenism subgroup without statistical significance. The logistic regression model of PCOS revealed that 2D:3D, 2D:4D, 2D:5D, and 3D:4D of left hands were statistically related to the diagnosis of PCOS among all the digit ratios. Conclusion: Not only 2D:4D but also other digit ratios, such as 2D:3D and 2D:5D, are a marker of prenatal testosterone exposure and may be an anatomical marker of PCOS. The majority of these significant differences included left 2D, with the following order: non-PCOS women > PCOS women > men.

Digit ratio (2D:4D), laryngeal cancer and vocal fold leukoplakia.

BACKGROUND: To date, there are no studies that have analyzed the possible influence of exposure to prenatal sex hormones on the risk of laryngeal cancer (LC) and premalignant laryngeal lesion-vocal fold leukoplakia (VFL). Digit ratio (2D:4D) is suggested to be a proxy of prenatal sex hormone exposure. OBJECTIVE: To examine 2D:4D in patients with LC and clarify if it could add to the verified risk factors in estimating the overall risk of LC. METHODS: 511 subjects participated in the study. The study group included 269 patients: with LC (N = 114, 64 men) and VFL (N = 155, 116 men). Controls included 242 healthy individuals (66.40 ± 4.50 years (106 men)). RESULTS: Predictive models estimating the risk of VFL and LC in women, based solely on predictors like smoking and alcohol consumption had a lower area under the ROC curve (AUC) than the model with left 2D:4D. AUC for the model estimating the likelihood of VFL increased from 0.83 to 0.85, and for LC from 0.76 to 0.79. CONCLUSIONS: Low left 2D:4D may be associated with an increased risk of developing leukoplakia and laryngeal cancer in women. In the case of laryngeal cancer, left 2D:4D may serve as additional variable (to other known risk factors, such as smoking and/or alcohol consumption), which can improve cancer risk prediction.

Dark Triad personality traits, second-to-forth digit ratio (2D:4D) and circulating testosterone and cortisol levels.

INTRODUCTION: Dark Triad (DT) personality traits (psychopathy, Machiavellianism, and narcissism) show sex differences and associations with hormones. Understanding aetiology may assist in mitigating the harm of these potentially adverse characteristics. Low second-to-fourth digit ratio (2D:4D) is hypothesised to be a marker of high prenatal testosterone exposure and may provide important information about organisational hormones. The aim of the present study was to measure Dark Triad and Big 5 personality traits in relation to digit ratio, salivary testosterone, and cortisol. METHODS: A non-clinical sample (N = 268; 49.25% Female, age M25.20 ± 8.77 yrs) completed the Short Dark Triad and International Personality Inventory Pool - Mini. Afternoon saliva was analysed for testosterone and cortisol, and 2D:4D finger ratios were measured. RESULTS: Males scored higher on DT traits than females. Females scored higher on Big 5 agreeableness and neuroticism. Males had higher testosterone and cortisol levels and lower 2D:4D than females. Digit ratio correlated inversely with salivary testosterone, Machiavellianism, and psychopathy. Testosterone levels correlated positively with cortisol levels and psychopathy and negatively with agreeableness, neuroticism, and Machiavellianism. CONCLUSIONS: These results provide indications that Machiavellianism and psychopathy (Dark Triad) traits, but not narcissism or Big 5 traits, are linked to markers of prenatal testosterone exposure. Results also replicate sex differences seen in 2D:4D digit ratios, with males having a shorter second-relative-to-forth finger. Links between circulating testosterone, digit ratios, cortisol and personality traits provide further information about potential biological bases of personality.

The association of prenatal amniotic sex hormones and digit ratio (2D:4D) in children aged 5 to 70 months: A longitudinal study.

The sex difference of the 2D:4D digit ratio (female > male)-a proposed marker for prenatal testosterone exposure-is well established. Studies suggest it already exists in utero and is of moderate effect size in adulthood. However, evidence for the claim that 2D:4D reflects prenatal androgen action is limited, and the sex difference may exhibit lability during childhood. In the present study, 244 mothers were recruited in the course of an amniocentesis examination (performed between gestational weeks 14 and 18). Prenatal testosterone (T) and estradiol (E) levels were determined from amniotic fluid for boys and girls. The majority (97.4%, n = 114) of available female T levels (n = 117) were found below the level of quantification. Therefore, only male amniotic fluid data (n = 117) could be included for the analysis of associations between amniotic sex hormones (T levels and T to E ratio (T/E)) and 2D:4D. The families were then invited to each of the five consecutive follow-ups (ages: 5, 9, 20, 40, and 70 months) where children's 2D:4D was measured for both hands. The alternative marker D[r-l] reflects the directional asymmetry of 2D:4D (right subtracted by left 2D:4D) and was subsequently calculated as an additional measure for prenatal T exposure. No significant correlations between amniotic T or the T/E ratio (measured between week 14 and 18 of gestation) with 2D:4D respectively D[r-l] were observed for any time point. There was a significant sex difference (females > males) and a significant age effect with moderate correlations of 2D:4D between time points. 2D:4D increased between 20 and 40 months and between 40 and 70 months of age. The findings raise questions regarding the applicability of 2D:4D as a marker for prenatal androgen action and are discussed in terms of the reliability of obtained digit ratio data as well as in terms of the developmental timing of amniocentesis.

High digit ratio (2D:4D) is associated with attack frequency and severity in hereditary angioedema patients.

BACKGROUND: Hereditary angioedema (HAE) caused by a deficiency or dysfunction of the plasma protease C1-inhibitor is a rare autosomal-dominant disorder. We explored a possible correlation between the ratio of the second and fourth finger lengths (2D:4D) and the frequency of HEA attacks, and whether the ratio might predict laryngeal attack. METHOD: We evaluated 35 HEA patients aged 19 to 66 years; 3 were subsequently excluded. The 2D:4D ratio was calculated by dividing the length of the second finger by that of the fourth finger of both hands. A structured clinical questionnaire exploring HAE course and treatment over the prior year was administered. RESULTS: Of the 32 participants, 56.25 % (n = 18) were female. Of them, those with high 2D:4D ratios suffered significantly more laryngeal attacks than others; 93.3% of patients with high 2D:4D ratios experienced ≥5 attacks annually, significantly more than those with low ratios. Among type 2 HEA patients, 75 % of those experiencing ≥5 attacks annually had high 2D:4D ratios; all patients with low 2D:4D ratios reported <5 attacks annually. These significant effects were found for right-hand 2D:4D ratios and not left-hand 2D:4D ratios. CONCLUSION: The data suggest that intrauterine sex hormone exposure, which affects the 2D:4D ratio, is significantly associated with HEA attack frequency and severity, and laryngeal edema.

Second to fourth digit ratio in women with breast cancer / Relación del segundo al cuarto dígito en mujeres con cáncer de mama

SUMMARY: Digit ratio established in utero is positivelly correlated with intrauterine level of estrogen. Since the breast cancer is related to excessive and prolonged exposure to estrogen, digit ratio might be considered as useful marker in breast cancer risk assessment. The aim of the present study was to compare digit ratios in breast cancer patients and healthy controls. The study group consisted of 98 breast cancer patients aged between 29 to 84 years while the control group included 141 healthy women aged between 21 and 67 years. After collecting anamnestic data concerning menopausal status, the length of second and fourth fingers were measured and the digit ratios were calculated for both hands, as well as the difference between right and left digit ratio. Digit ratio was significantly higher on right hand in breast cancer patients compaired to healthy controls (1.003±0.05 vs. 0.990±0.03). Right digit ratio showed better predictive capacity for the breast cancer development then the left (AUC:0.609 vs. 0.541). Negative statistically significant correlation between right digit ratio and the age of breast cancer diagnosis was observed (r=-0.271). Higher values of right digit ratio in women with breast cancer when compared to healthy women suggest their higher prenatal estrogen exposure that confirms the importance of digit ratio determination in breast cancer risk assessment.

La proporción de dígitos establecida en el útero, se correlaciona positivamente con el nivel intrauterino de estrógeno. Dado que el cáncer de mama está relacionado con una exposición excesiva y prolongada a los estrógenos, la proporción de dígitos podría considerarse un marcador útil en la evaluación del riesgo de cáncer de mama. El objetivo del presente estudio fue comparar proporciones de dígitos en pacientes con cáncer de mama y controles sanos. El grupo de estudio consistió en 98 pacientes con cáncer de mama con edades comprendidas entre los 29 y los 84 años, mientras que el grupo de control incluyó a 141 mujeres sanas con edades comprendidas entre los 21 y los 67 años. Después de recopilar datos anamnésticos sobre el estado menopáusico, se midió la longitud de los dedos segundo y anular y se calcularon las proporciones de los dedos para ambas manos, así como la diferencia entre la proporción de los dedos derecho e izquierdo. La proporción de dígitos fue significativamente mayor en la mano derecha en pacientes con cáncer de mama en comparación con controles sanos (1,003 ± 0,05 frente a 0,990 ± 0,03). La proporción del dígito derecho mostró una mejor capacidad predictiva para el desarrollo de cáncer de mama que el izquierdo (AUC: 0.609 vs. 0.541). Se observó una correlación estadísticamente significativa negativa entre la proporción de dígitos derechos y la edad del diagnóstico de cáncer de mama (r=-0,271). Los valores más altos de la proporción de dígitos derechos en mujeres con cáncer de mama en comparación con mujeres sanas sugieren una mayor exposición prenatal a estrógenos que confirma la importancia de la determinación de la proporción de dígitos en la evaluación del riesgo de cáncer de mama.

Investigating the correlation between 2D:4D finger digit ratios and attention gathering skills of 60-72 month-old children.

BACKGROUND: Digit ratio 2D:4D is used to follow children's development process and examine behaviours and abilities. AIM: The aim of this study is to determine the correlation between the 2D:4D digit ratios of 60-72 month-old children and their attention gathering skills, as well as whether the 2D:4D digit ratio and attention gathering skills of children differ based on independent variables. METHOD: The sample of the study, designed in the correlational survey model, consisted of a total of 112 children aged 60-72 months who were attending preschool education in Malatya province in Turkey. The data were analysed using SPSS packaged software. RESULTS: It was determined that there was a positive low significant correlation between attention gathering skills and the right hand 2D:4D digit ratio in 60-72 month-old children. In addition to, no significant difference was found between the children's FTF-K scores and the right hand 2D:4D digit ratio in terms of the variable of mother's status of exercising, but there was a significant difference between their FTF-K scores and the left hand 2D:4D digit ratio in terms of the variable of the mother's status of exercising. CONCLUSIONS: The findings of the study demonstrate the importance of the study for revealing clues about children's attention gathering/concentration levels from their early periods, and promoting their attention gathering skills and generally their cognitive development.

No association between developmental instability as a general measure of stress and 2D:4D digit ratios in a non-western sample.

OBJECTIVE: Random deviation from perfect symmetry of organisms is defined as fluctuating asymmetry. Fluctuating asymmetry is widely considered to be a marker of developmental instability, developmental noise and phenotypic quality at the population level. In this study, we investigated hypothesized relationship between 2D:4D digit ratios as a proxy measure of prenatal sex hormones and developmental instability levels in young adult humans. MATERIALS AND METHODS: In the study, seven bilateral traits were measured for fluctuating asymmetry, as well as second and fourth digit lengths on both hands of 185 individuals, 87 men (mean age: 22.42 ± 3.37) and 97 women (mean age: 22.88 ± 3.87). The second digit length was divided by the fourth digit length and the resulting value was used as the digit ratio (2D:4D). Composite fluctuating asymmetry was calculated using five bilateral traits displaying fluctuating asymmetry. RESULTS: Only the right hand 2D:4D ratio is lower in men than in women. However, this difference disappears when the effect of digit lengths is controlled. Composite fluctuating asymmetry results reveal that men are more asymmetrical than women. There was no significant relationship between digit ratios and composite fluctuating asymmetry. CONCLUSION: In this study, the 2D:4D digit ratios appear to be influenced (at least in humans) by different digit lengths. This study also confirms previous studies that digit ratios as a proxy measure of exposure to either high testosterone or estrogen levels during early development does not appear to affect levels of developmental instability.

Effects of caste, birth season, and family income on digit ratios.

OBJECTIVES: The contributions of latitude and ethnicity in the determination of cross-society differences in digit ratios are unclear. In India, different castes (endogamous groups) have been living in the same areas (villages or towns) for the last 1500 years and, therefore, these groups may have different gene pools without a latitude-related difference component. Thus, in the present study, we studied the effect of caste on digit ratios. We also studied the effects of sex, birth season, and family income on digit ratios. METHODS: We selected a sample of 301 college students (age: M = 19.9 years, SD = 2.63) in Muzaffarnagar city of western Uttar Pradesh, India, and asked participants for information regarding their birth month, religion, caste, and monthly family income. We measured participants' dorsal and palmar digit lengths (of all fingers, except the thumb, in both hands) using vernier calipers of 0.01 mm accuracy. RESULTS: Other backward castes (intermediate castes) had longer digit lengths than general castes (upper castes), scheduled castes (lower castes), and Muslims. However, there was no difference in digit ratios of caste groups (scheduled castes vs. other backward castes vs. general castes vs. Muslims) or specific castes (Chamar-Jatav vs. Jat vs. Pandit-Tyagi). Winter-born women had lower left dorsal 2D:4D and 3D:4D ratios than summer-born women. Family income was related to higher dorsal 2D:4D and 3D:4D ratios among women. Moreover, in dorsal digit ratios, sex difference (men < women) occurred in digit ratios constituting digit 5, whereas, in palmar digit ratios, sex difference occurred in digit ratios constituting digit 2. CONCLUSIONS: The present study suggests that endogamy-led genetic difference in ethnic/caste groups is not a determinant, whereas birth season (i.e., the exposure to sunlight) and family income might be determinants of digit ratios. In addition, compared to palmar digit ratios, dorsal digit ratios are better markers of sexual dimorphism.

Association between the second- and fourth-digit ratio and oral squamous cell carcinoma.

OBJECTIVES: Using an established proxy measure of intra-utero testosterone and estrogen levels-the ratio of second- and fourth-digit lengths-we estimated its association with the oral cancer risk among a population from Southern India. MATERIAL AND METHODS: In a hospital-based case-control study, incident oral cancer cases (N = 350) and non-cancer controls (N = 371), frequency-matched by age and sex, were recruited from two major referral hospitals in Kerala, India. Structured interviews collected information on several domains of exposure via detailed life course questionnaires. Digit lengths were measured using a ruler in a standardized manner. Unconditional logistic regression was performed to estimate the odds ratios and 95% confidence intervals. RESULTS: Second- and fourth-digit ratio lower than 1, which indicates relatively higher intra-utero level of testosterone and lower intra-utero level of estrogen, was associated with higher oral cancer risk (OR = 1.60, 95% CI: 1.02-2.52), after accounting for several confounders. CONCLUSION: Our findings suggest that intra-utero hormonal levels measured by second- and fourth-digit ratio are associated with oral cancer risk. Further studies in different population should confirm these results.