Sex differences and bilateral asymmetry in dermatoglyphic pattern elements on the fingertips

Dermatoglyphics in hypertension: a review

Hypertension is a major contributor to the global burden of disease and mortality. A major medical advancement would be a better means to ascertain which persons are at higher risk for becoming hypertensive beforehand. To that end, there have been a number of studies showing that certain dermatoglyphic markers are associated with hypertension. This association could be explained if the risk toward developing hypertension later on in life is somehow connected with fetal development of dermatoglyphics. It would be highly valuable from a clinical standpoint if this conjecture could be substantiated since dermatoglyphic markers could then be used for screening out individuals who might be at an elevated risk of becoming hypertensive. The aim of this review was to search for and appraise available studies that pertain to the association between hypertension and dermatoglyphics.

A systematic literature search conducted using articles from MEDLINE (PubMed), Trip, Cochran, Google scholar, and gray literature until December 2014. Of the 37 relevant publications, 17 were included in the review. The review performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement.

This review showed a fairly consistent finding of an increased frequency of whorl patterns along with a higher mean total ridge count in digital dermatoglyphic results in hypertensive samples compared to controls. However, it was imperative to discuss several limitations found in the studies that could make this association as yet unsettled.

Sex differences in human brain asymmetry: a critical survey

Dual functional brain asymmetry refers to the notion that in most individuals the left cerebral hemisphere is specialized for language functions, whereas the right cerebral hemisphere is more important than the left for the perception, construction, and recall of stimuli that are difficult to verbalize. In the last twenty years there have been scattered reports of sex differences in degree of hemispheric specialization. This review provides a critical framework within which two related topics are discussed: Do meaningful sex differences in verbal or spatial cerebral lateralization exist? and, if so, Is the brain of one sex more symmetrically organized than the other? Data gathered on right-handed adults are examined from clinical studies of patients with unilateral brain lesions; from dichotic listening, tachistoscopic, and sensorimotor studies of functional asymmetries in non-brain-damaged subjects; from anatomical and electrophysiological investigations, as well as from the developmental literature. Retrospective and descriptive findings predominate over prospective and experimental methodologies. Nevertheless, there is an impressive accummulation of evidence suggesting that the male brain may be more asymmetrically organized than the female brain, both for verbal and nonverbal functions. These trends are rarely found in childhood but are often significant in the mature organism.

Dermatoglyphic and anthropometric relationships within the Iñupiat (Eskimo) hand

On the basis of earlier findings with Easter Islanders suggesting a positive correlation between dermatoglyphic variables and hand anthropometric measurements, the present study was designed to determine if such a relationship could be generalized to another population, namely, Iñupiat (Eskimo). Since some dermatoglyphic and anthropometric variables were available for both sides of the body, the extension of this study to explore the question of asymmetry was also possible. The Iñupiat sample numbered 142 male and 176 female adult inhabitants of five Alaskan North Slope communities. The major findings of this study included, for males, significant negative correlations between left arm length and digital ridge counts and positive relationships between the palmar variable of axial index and hand length on both hands. For females, the hand breadth/length index was negatively related to most of the digital variables. Very little definitive information regarding the relationship of the asymmetry variables between the two types of measures was ascertained.

Inbreeding effects on bilateral asymmetry of dermatoglyphic patterns

Bilateral correlations are higher and bilateral variances within individuals smaller in the samples of inbred individuals than in matched control groups of the same sex for pattern intensities on fingers in four series of data and also for pattern intensities on palms, toes, and soles and the palmer main line indices in the data collected from a Muslin population of West Bengal. This trend is not apparent in two series of data from the Yanadi tribe, in which the inbred and noninbred samples are not controlled for random variation of genes and environment. Increased variances between individuals and changes in means and distributions of the traits in the inbred samples of the matched data indicate some influence of homozygosity of genes for the traits on their asymmetry. The reduced variability of asymmetry of the traits in the inbred cannot be explained by homozygosity of genes for either directional or absolute asymmetry. One possible explanation is that heterozygotes for these dermatoglyphic triats are more responsive to environmental stress than homozygotes and/or increased selection in the homozygotes against genetic disorders associated with dermatoglyphic asymmetry may reduce the variability of such asymmetry.

Easter Islander palmar dermatoglyphics: sexual dimorphism, bilateral asymmetry, and family polymorphism

The palmar prints of 297 male and female Easter Islanders were analyzed according to the Penrose and Loesch topological classification system. While the frequencies of most pattern elements were not found to differ significantly between the sexes, the placement of the axial triradius was found to be highly significant (P less than 0.01). Both males and females were found to exhibit considerable bilateral asymmetry in the a-b count and in the atd angle, but there was no significant difference between the sexes in the amount of asymmetry expressed. Family data for a small subset of the sample (51 individuals) were subjected to further statistical analysis, from which significant results (P less than 0.05) were obtained both on chi-square tests for frequency of pattern elements and ANOVA tests for a-b counts, atd angle, and A-line exit. The implications of these results are considered from a developmental perspective. It is suggested that a particular pattern combination (termed a formula) could be used to represent a default value and that other formulae might then be considered as deviations from this default value. Such variation, theoretically at least, might be traced to genetic influences or to the embryological environment present during the time of dermatoglyphic formation.

The influence of sex chromosomes on finger dermatoglyphic patterns

Finger pattern frequencies for patients exhibiting various sex chromosome aneuploidies were obtained from literature sources. The sample consisted of 141 XO, 500 XX, 68 XXX, 9 XXXX, 500 XY, 93 XYY, 30 XXYY and 6 XXXXY. Pattern frequencies were converted to radial and ulnar loop frequencies, and these in turn were used to construct four variables; pattern intensity; radial-ulnar difference; radial loop asymmetry; and ulnar loop asymmetry. The relationship between the dermatoglyphic variables on to the sex chromosomes was examined by regressing the dermatoglyphic variables on to the number of X and Y chromosomes. Radial-ulnar difference and radial loop asymmetry showed the strongest relationship with the number of X and Y chromosomes. The X and Y chromosomes had about equal influence on radial-ulnar difference, but the Y had a stronger effect on radial loop asymmetry. It is postulated that sex chromosomes influence dermatoglyphic development by controlling tissue sensitivity to fetal sex steroids.

The analysis of whorls on specific fingertips with respect to sex, bilateral asymmetry, and genetic relationship

In a sample of 539 Polish families, 1000 individuals (515 males and 485 females) were analysed to determine the distribution of whorl patterns on specific fingertips, to compare their frequencies in males and females, and to determine whether asymmetry of these dermatoglyphic pattern elements is genetically controlled. Whorls occur most commonly on digit VI on both hands and in both sexes. The difference between males and females for mean values of occurrence is not significant. Using the bimanual difference between hands (right minus left), the digital asymmetry was determined, and correlations with asymmetrical occurrence of whorls was made between parents and children, and between sibs, in all combinations. In each case, there was a positive correlation pairs of relatives, demonstrating a genetic component in whorl determination and their asymmetrical occurrence.