|ISSN No. 1606-7754 Vol.9 No.1&2 April, August 2001|
Plantar and digital dermatoglyphic patterns in Malawian
patients with diabetes, hypertension and diabetes with hypertension
PS Igbigbi, BC Msamati, TM Ng'ambi
Department of Anatomy, College of Medicine, Univeristy of Malawi, Private Bag 360, Blantyre 3, Malawi
In this study we examined the dermatoglyphic features of 99 Malawian patients with diabetes, hypertension and diabetes with hypertension, attending the outpatient clinic at Lilongwe and Queen Elizabeth Central Hospitals. Plantar and digital pattern types were determined and their variability was calculated using Dankmeijer’s (DI) and pattern intensity (PII) indices. The results showed that the soles of all patients had more loops than arches and more arches than whorls, which were restricted to the distal zones. In hypertension, whorls were found in zones I, II and III whereas in patients with diabetes and hypertension, the whorls were seen in zones I, III and IV. In digits the most predominant ridge pattern were arches in all patients, followed by loops and whorls were absent. In the first digit, diabetic patients had no arches but women hypertensives showed arches. In patients with diabetes and hypertension, arches were present in both sexes but in men it was confined to the right foot. Loops were only found in the first digit in all patients. The frequency of loops was highest in diabetic patients, high in diabetics with hypertension and least in patients with hypertension alone. Using PII and DI indices, there were significant differences between patients and healthy Malawian subjects (P < 0.001), and between the sexes (P < 0.01), but PII did not show significant differences with sex (P > 0.5) in hypertensives. Diabetic patients had the lowest mean DI when compared to the other groups. In conclusion, this study has demonstrated plantar and digital dermatoglyphic differences between patients and healthy Malawians, differences that were exhibited more in digital than in plantar ridge patterns. The disease conditions were indicated better by whorls in topographical zones IV of the sole and by the presence and frequency of loops in the first digit.
Key words: Planar dermatoglyphics, diabetes and hypertension.
The science of dermatoglyphics involves the study of epidermal ridges present on the surface of palms, fingers, soles and toes.1,2 These epidermal ridges form well-defined patterns that characterise individuals and they have been found useful in the clinical diagnoses of hereditary diseases.3 Epidermal ridge patterns form early in fetal development and they remain unchanged throughout life and hence they could be used to indicate gene or chromosomal abnormalities4.
Studies in Indians have shown links between diabetes mellitus and dermatoglyphic features.4-9 Although the total finger ridge count (TFRC) in diabetics has been reported by various workers with contradicting results,5-7 these authors nevertheless demonstrated that the ridge patterns are affected one way or the other by diabetes mellitus. However, their findings were restricted to palmar and digital ridge patterns alone. The literature on plantar dermatoglyphics for diabetics is lacking and reports on black African subjects in general are not available. Essential hypertension is another condition with genetic influence. It is defined as sustained high blood pressure not attributable to a single cause but reflecting the interaction of multiple genetic and environmental influences, such that siblings of hypertensive parent or parents stand a higher chance of developing hypertension in later life10. As with diabetes, no dermatoglyphic reports on black subjects are available.
Since palmar dermatoglyphic patterns have been demonstrated in diabetic patients, are there specific plantar patterns in addition? Secondly, do such patterns also exist in essential hypertensives, and in patients with both diabetes and essential hypertension? In an attempt to answer these questions we carried out this study on adult black Malawian patients.
Materials and methods
We recruited 99 indigenous Malawian patients aged 25 – 66 years attending the medical outpatient clinic for diabetes mellitus, essential hypertension and a combination of the two conditions at Lilongwe and Queen Elizabeth central hospitals. They consisted of 27 diabetics (15 males, 12 females), 21 hypertensives (9 males, 12 females) and 51 diabetics with hypertension (21 males, 30 females). All patients were diagnosed after the age of 20 years and suffered from Type 2 diabetes.
The sole was mapped topographically into 10 zones based on Cummins and Midlo’s 1961-nomenclature,11 where zones I-V represented the distal plantar sole and zones VI - X represented the proximal plantar sole. These were the zones used to describe the characteristics reported in the study (Fig. 1, Table 1).
Bilateral plantar and digital prints of the sole were obtained by the inking method of Cummins and Midlo11. The various plantar and digital patterns of arches, loops and whorls (Fig. 2) were counted and classified with the aid of a hand lens using Loesch and Skrinjaric’s method12. The frequencies of the ridge patterns were expressed as percentages of the total pattern types and analysed using Cummins and Midlo’s method11.
The Dankmeijer (DI) and pattern intensity (PII) indices determined the digital variability of patterns. The DI is the total frequency of arches divided by the total frequency of whorls x100,13 while the PII is the mean number of triradii found on toes per individual. Using those indices the frequencies of ridge patterns in the different digits were compared with normal patterns of Malawian subjects we had studied previously, matched for sex and age.
Inter-observer variation in counting was eliminated as only one ‘blinded’ person who did not collect the prints examined all the prints. Chi-square tests were applied to the variables of arches, whorls and loops while t-Tests were applied to the DI and PII variables.
Plantar ridge patterns
Digital ridge patterns
Arches were the most predominant ridge pattern in all patients followed by loops but whorls were absent.
However none of these differences are statistically significant
Digital ridge patterns of patients and healthy Malawians
Table 4 compares the digital ridge variability in patients and healthy subjects, each disease category being compared separately. Both PII and DI indices were significantly different between patients and healthy subjects (P< 0.001), between males and females (P<0.01), but hypertensives did not show significant differences between the sexes (P>0.5) using PII. Diabetic patients had low mean DI when compared to all other groups.
Plantar ridge patterns
We have reported probably for the first time in a black African sample the presence of whorls in the first topographical zone of the sole in hypertensive patients. Since this was not observed in healthy Malawians we studied previously14 and in diabetics or in diabetics with hypertension, the finding would appear to suggest that plantar whorls are restricted to the first topographical zone of the sole in hypertension. This effect, however, seems to be masked where the hypertension co-exists with diabetes mellitus (Table 3). In the absence of other reports on blacks or blacks in Africa, this finding is difficult to explain. The report by Wilder15 on plantar ridge patterns among Japanese, Chinese and European-Americans only considered healthy subjects. On the other hand, the studies by Wichman16 and Komatz et al,3 reported on Caucasians, the former on healthy Germans and the latter on patients with Klinefelter’s syndrome, respectively. Reports on black Africans are lacking, but we suggest that the effect could be genetic, racial or environmental.
The first topographical zone of the sole includes the first digit,11 and corresponds to the hallucal zone used by Komatz et al,3 These workers showed that patients with Klinefelter’s syndrome exhibited special hallucal ridge patterns. The first topographical zone exhibited both plantar and digital features that could distinguish the three conditions in the present study. In hypertensive patients, whorls were only found in topographic zone I; in diabetes mellitus alone, whorls were found in zones I, II and III; and in diabetes with hypertension, whorls were seen in zones III, IV and I (Table 2a, b, c). It would appear from this study that plantar whorls showed disease better in our series.
The prominence of digital arches and loops in all patients sampled in this study merely confirms the observations in healthy Malawians, where whorls were also absent on all digits, highlighting further the peculiarity of black Malawians.14 We have also demonstrated that loops were restricted to the first digit in the three categories of patients, a finding that again differentiates these patients from healthy subjects. We have reported for the first time in black Malawians that patients with diabetes alone showed the highest frequency of loops than diabetics with hypertension, and those with hypertension alone (Table 3). We believe this trend could only be due to genetic influences by these diseases.
The complete absence of arches on the first digit of diabetes mellitus patients differentiates them from healthy individuals. It was interesting, however, to note that the arches were present in the first digit when diabetes co-existed with hypertension (Table 3). Furthermore, in hypertension, the arches were only present in women, while in diabetes with hypertension, the arches were present in both sexes but confined to the right foot in men (Table 3a, b, c). On the other hand, the fact that the frequency of loops was highest in diabetes mellitus, high in diabetics with hypertension and least in patients with hypertension alone (Table 3a, b, c), suggests that loops differentiated diabetes mellitus, essential hypertension and diabetes with hypertension better than arches.
The digital ridge patterns indicated above were further confirmed by the PII and DI indices. Using these indices, the patients were correctly classified into the three categories of patients in our series and the groups were found to differ from healthy Malawians. These findings become important when one realises that epidermal ridge patterns form early in fetal life and remain unchanged throughout life.4 Could they therefore serve as reliable indicators of genetic abnormality? Using palmar and digital dermatoglyphics a number of studies have indicated that indeed this is the case with diabetes mellitus.4,5,9 The present findings suggest that the same could also apply to the ridge patterns of the sole.
Plantar dermatoglyphics have received relatively little attention when compared to palmar ridge patterns. This has been attributed to the difficulty of obtaining prints and classifying them from the soles when compared to those from palms. For this reason little attention has been given to studies of plantar and digital ridge patterns of hereditary diseases like diabetes and hypertension from the sole. Notwithstanding this, genetic, racial, sexual and regional differences have been exhibited by the sole from the few studies of other racial groups on healthy subjects.15,16 Studies in sub-Saharan Africa have examined healthy indigenous black Malawians14 and Nigerians.17,18 On the other hand, Komatz et al,3 studied the hallucal ridge patterns for the clinical diagnosis of patients with Klinefelter’s syndrome. However, there appear to be no other published reports on plantar and digital ridge patterns in genetic diseases in Africans.
This study has highlighted differences in plantar and digital dermatoglyphic features between patients and healthy Malawians. The differences exhibited were demonstrated better in digital than in plantar ridge patterns. The specific ridge patterns that have emerged from this study showed that whorls in the topographical zones I – IV of the sole as well as the presence and frequency of loops in the first digit, were indicators of these conditions. We suggest that these findings could be used to predict the occurrence in later life of diabetes mellitus, hypertension and hypertension with diabetes in children in Malawi.