A case of symbrachydactyly with oligodactyly

The term symbrachydactyly describes syndactyly accompanied by brachydactyly. Brachydactyly is seen in middle phalanges of both hands and feet and very short in length or absent. As for syndactyly it is a cutaneous type. It has always been observed unilaterally and sporadically. A familial type of this syndrome has also been reported. There have been many classifications of symbrachydactyly. Of these, Blauth classification is the most favored one. Yet these classifications have been inadequate to include many recently discovered other forms of symbrachydactyly. A three month old child was brought to the Istanbul University Genetic Research Center because of his abnormal hands and feet. He was the second child of a couple who had no kinship ties to each other. In the history of the family, there was no mention of any anomaly as such. There was a complete syndactyly involving the 3rd through the 5th fingers, partial syndactyly between the 2nd and 3rd, and the thumb was normal in the right hand. There was only one finger in the left hand. There was total syndactyly in four toes of the right foot with oligodactyly and absence of the big toe. The left foot had five toes with a complete syndactyly between the 2nd and the 3rd. Radiological observation indicated that the middle phalanges of both extremities were rudimentary or never developed. There was no osseous syndactyly. As observed in this case, oligodactylous type that is bilateral and involves both hands and feet together is very unusual. The purpose of this study is to present a rare case of this anomaly that requires a reassessment of symbrachydactyly and its traditional classifications.     

Integration,heterochrony, and adaptation in pedal digits of syndactylous marsupials

Background  

Marsupial syndactyly is a curious morphology of the foot found in all species of diprotodontian and peramelemorph marsupials. It is traditionally defined as a condition in which digits II and III of the foot are bound by skin and are reduced. Past treatments of marsupial syndactyly have not considered the implications of this unique morphology for broader issues of digit development and evolution, and the ongoing debate regarding its phylogenetic meaning lacks a broad empirical basis. This study undertakes the first interdisciplinary characterisation of syndactyly, using variance/covariance matrix comparisons of morphometric measurements, locomotor indices, ossification sequences, and re-assessment of the largely anecdotal data on the phylogenetic distribution of tarsal/metatarsal articulations and "incipient syndactyly".     

Toe and plantar dermatoglyphics in adult American Caucasians

The scarcity of information on control data of toe and plantar dermatoglyphics led us to undertake this study of adult American Caucasians. Toe and sole prints of 168 male and 83 female participants of the Baltimore Longitudinal Study of Aging were analyzed. Toe pattern frequencies demonstrate that fibular loops are the most prevalent pattern on the toes in both males and females. Pattern distribution by digit shows that arches are most often located on the fifth toe while whorls are found with greatest frequency on the third toe. Plantar pattern frequencies indicate that the most common pattern found in the hallucal area is the distal loop. Open fields are frequently found in the II and IV interdigital areas while distal loops are prevalent in the III area. These results are compared to the finger and palmar patterns of the same individuals. The distribution of patterns on the toes and fingers of the same individuals appear to be quite different. Population comparisons did not demonstrate a clear racial difference in the toe pattern frequencies or in the plantar areas.     

De novo translocation (2;18)(q21;q22) in a child with severe epilepsy, developmental delay and mild dysmorphism

De novo translocation (2;18)(q21;q22) in a patient with severe epilepsy developmental delay and mild dysmorphism: We report on a patient presenting with severe epilepsy, hypotonia, developmental delay, blepharophimosis, low-set ears, camptodactyly and tapering fingers, and cutaneous syndactyly of toes II and III of the right foot. The MRI showed some loss of volume of the white matter and delayed myelination, no other specific anomalies were present. Chromosome analysis revealed a translocation involving chromosomes 2 and 18, which was characterized further by FISH using band-specific probes. The possibility of a submicroscopic deletion is discussed and the patient is compared with patients reported in the literature with either 2q21 or 18q22 deletion.     

The developmental origin of zygodactyl feet and its possible loss in the evolution of Passeriformes

The zygodactyl orientation of toes (digits II and III pointing forwards, digits I and IV pointing backwards) evolved independently in different extant bird taxa. To understand the origin of this trait in modern birds, we investigated the development of the zygodactyl foot of the budgerigar (Psittaciformes). We compared its muscular development with that of the anisodactyl quail (Galliformes) and show that while the musculus abductor digiti IV (ABDIV) becomes strongly developed at HH36 in both species, the musculus extensor brevis digiti IV (EBDIV) degenerates and almost disappears only in the budgerigar. The asymmetric action of those muscles early in the development of the budgerigar foot causes retroversion of digit IV (dIV). Paralysed budgerigar embryos do not revert dIV and are anisodactyl. Both molecular phylogenetic analysis and palaeontological information suggest that the ancestor of passerines could have been zygodactyl. We followed the development of the zebra finch (Passeriformes) foot muscles and found that in this species, both the primordia of the ABDIV and of the EBDIV fail to develop. These data suggest that loss of asymmetric forces of muscular activity exerted on dIV, caused by the absence of the ABDIV, could have resulted in secondary anisodactyly in Passeriformes.     

Secondary centers of ossification of the human toes: exceptional polymorphism and evolutionary perspectives

As great morphological variability characterizes the phalanges of the human toes in adults, we hypothesized for a possible variability in the presence or absence of their secondary (= epiphyseal) centers of ossification linked to the unique morphology of the human foot within primates. The aim of this study was thus to provide original and detailed data on the occurrence of these centers. Classically, the big toe or hallux (I) presents two secondary centers and the lateral toes (II-V) three centers, and consequently the five toes present a total of 14 secondary centers. The material studied consisted of 261 foot radiographs from 261 young individuals of European origin (202 males and 59 females; 6-16 years). The presence (or absence) of the secondary centers of the phalanges of the toes was assessed for each foot. Feet presenting a biphalangeal variant in one or more lateral toes were studied separately. The theoretical possibilities of association of the three secondary centers in a given lateral toe (II-V) are eight in number; these eight patterns were studied and coded in the present study by types A-H. An exceptional variability in the occurrence of the secondary centers in lateral toes (II-V) was observed, and the classic pattern of phalangeal ossification was never observed. The absence of one or more secondary centers seems to be observed only in the human species, and we suggest that this could be a derived pattern specific to the human species, i.e., autapomorphic pattern. These results are of interest in the characterization and understanding of the reduction in size of the lateral toes which characterizes the specific evolution of the human foot.     

Polydactyly of the foot: an analysis of 265 cases and a morphological classification.

Three hundred and thirty feet in 265 patients with polydactyly of the foot were classified on the basis of ray involvement and the level of duplication. Anatomic differences in bony structures according to x-ray and operative findings, external appearance of involved digits, associated anomalies, and familial incidence were studied. In medial-ray polydactyly, bilateral occurrence was common, and a higher frequency of associated anomalies was detected. Each involved foot with even the same level of duplication usually had a different morphologic pattern. In central-ray polydactyly, all patients except one had duplications of the second toe, commonly with unilateral involvement. Both components were underdeveloped, with delay in appearance of ossification areas. In two patients, each member of duplication had syndactyly with the neighboring toe, resembling the pattern of polysyndactyly-cleft hand complex. Lateral-ray polydactyl was classified into two new major groups based on ossification pattern and bony alignment: (1) fifty-ray duplication, referring to the medially duplicated supernumerary fifth toe, and (2) sixth-ray duplication, referring to the laterally duplicated supernumerary sixth toe. Fifth-ray duplication was much more frequent than sixth-ray duplication in the Japanese population. Many differences were noted between the two groups of lateral polydactyly. Syndactyly between the fourth and fifth toes was associated only with fifty-ray duplication. Ulnar polydactyly was associated only with sixth-ray duplication. In lateral polydactyly, every patient with bilaterally involved feet had similar groups of polydactyly bilaterally. All the patients in the same family also had similar groups of anomalies. These facts suggest independent etiologic mechanisms for each.     

Treatment of the hands and feet in Apert syndrome: an evolution in management

Apert syndrome is a relatively uncommon condition that is instantly recognizable on the basis of the pan-syndactylies involving both the hands and feet. For more than 10 years, the treatment of Apert syndrome hand and foot anomalies was approached in a comprehensive manner, with attempts to maximize the final results and minimize the total number of operations. Numerous conventions were abandoned in the development of this approach, with the introduction of some new methodologies, including (1) release of all 10 fingers, and toes, in only two operations, (2) elimination of routine digital amputations, (3) abandonment of the zigzag incision in favor of straight-line release, (4) substitution of equal-length anterior and posterior flaps for the long dorsal web space lining flap, (5) leaving of small areas of exposed bone without vascularized tissue coverage, and (6) performance of midphalangeal osteotomies, among older children, to improve hand function. Fifty-seven children with Apert syndrome have been treated at the author's center since 1990, and 43 underwent surgical treatment of their hands and feet by a single surgeon. Treatment can be separated into two phases, early (syndactyly releases) and late (functional osteotomies). Seventeen of those 43 patients were treated at the author's center from birth (type I, 11 patients; type II, two patients; type III, four patients), and 10 fingers and 10 toes were achieved for all patients in two operations. No digital amputations were performed for any of the 43 patients. However, four of 26 patients (15 percent) not treated at the author's center from birth had undergone at least one digital amputation before coming to the center. Twenty-two of those 26 patients required a two-stage syndactyly release to accomplish the separation of all 10 fingers and toes. Aside from the patients who had previously undergone amputations, all other patients successfully achieved 10 fingers and toes, except for one patient (38 of 39 patients, 97 percent). The average operative time for the first-stage syndactyly release of the hands and feet was 4 hours 11 minutes (range, 185 to 300 minutes), and that for the second stage was 3 hours 49 minutes (range, 160 to 300 minutes). Twenty-eight hands were treated with functional osteotomies, which involved permanent angulation of the fused phalanges at the proximal interphalangeal level, to create a "position of function" and provide pulp-to-pulp pinch. In addition, targeted osteotomies of the feet were performed for many of these patients, to decrease pain with walking. There were no major complications. Minor complications included one reexploration because of bleeding, early in the series. There were 13 incomplete secondary syndactylies that required a subsequent operative release (10 spaces treated at the author's center and three treated elsewhere), of a total of 342 spaces (3 percent author incidence). There were no scar contractures or functional limitations that required release. This distinctive protocol seemed to result in improved functional outcomes, with a reduction in the total number of operative procedures.     

Manganese inhibition of microbial iron reduction in anaerobic sediments

Potential mechanisms for the lack of Fe(II) accumulation in Mn(IV)‐con‐taining anaerobic sediments were investigated. The addition of Mn(IV) to sediments in which Fe(III) reduction was the terminal electron‐accepting process removed all the pore‐water Fe(II), completely inhibited net Fe(III) reduction, and stimulated Mn(IV) reduction. In a solution buffered at pH 7, Mn(IV) oxidized Fe(II) to amorphic Fe(III) oxide. Mn(IV) naturally present in oxic freshwater sediments also rapidly oxidized Fe(II). A pure culture of a dissimilatory FE(III)‐ and Mn(FV)‐reducing organism isolated from the sediments reduced Fe(III) to Fe(II) in the presence of Mn(IV) when ferrozine was present to trap Fe(II) before Mn(IV) oxidized it. Depth profiles of dissolved iron and manganese reported in previous studies suggest that Fe(II) diffusing up from the zone of Fe(III) reduction is consumed within the Mn(IV)‐reducing zone. These results demonstrate that preferential reduction of Mn(IV) by Fe(III)‐reducing bacteria cannot completely explain the lack of Fe(II) accumulation in anaerobic, Mn(IV)‐containing sedments, and indicate that Mn(IV) oxidation of Fe(II) is the mechanism that ultimately prevents Fe(II) accumulation.     

A New Surgical Technique for Polysyndactyly of the Toes without Skin Graft

Reconstruction for polysyndactyly of the toes aims at cosmetic improvement. A previous method that uses a skin graft has inherent disadvantages of mismatched pigmentation between the graft and the surrounding skin and scar formation at the donor site. The authors' new improved surgical technique for the treatment of polysyndactyly of the toes does not require a skin graft and therefore avoids these problems. The authors designed a subcutaneous flap from the distal portion of a rectangular flap of skin from the dorsal side of the interdigital webbing and moved the former flap to the sidewall of the base of a toe. Both flaps are the same size; therefore, an interdigital space had to be of sufficient size to accommodate both of them. To ensure an adequate blood supply to the flap, careful handling of the subcutaneous flap is essential for success. This procedure can apply to polysyndactyly of the fourth, fifth, and sixth toes when the fourth and fifth toes adhere over the distal side of the distal interphalangeal joint and when the skin on the dorsal side of the fifth toe, regarded as the excessive one, is at lease twice the size of the dorsal rectangular flap. Ten patients with polysyndactyly of the toe were treated with this method. Aesthetically good results were obtained.     

Reconstruction of bilateral metacarpal hands with multiple-toe transplantations.

Bilateral metacarpal hands, if not treated properly, leave a patient without prehensile ability in both hands. Since 1990, six patients with bilateral metacarpal hands caused by accidents have undergone reconstruction with multiple-toe transplantations. Four or five toes were used for each patient, with a total of 27 toes transplanted to the hands. There was no toe loss. One nonunion in a middle-finger reconstruction was treated successfully with bone grafting. Secondary operations for functional improvement included one joint fusion and one flexor tendon tenolysis. Only one patient required excision of a plantar callus 42 months postoperatively, whereas the other five patients reported no major donor-site problems in an average 57 months of follow-up time. The six patients continue all their daily activities independently. Although their jobs were changed, all adult male patients were able to return to regular work. Principles of reconstruction to achieve satisfying prehensile function combined with minor donor-site morbidity in bilateral metacarpal hands include an adequate soft-tissue coverage before toe transplantations, selection of digits to be reconstructed based on functional and individual requirements, selection of toes and number of toes to be harvested based on consideration of usefulness for the hands and of foot morbidity, and consideration of thenar function in planning the sequence of transplantations. In conclusion, given thorough planning, multiple toe-to-hand transplantations can provide adequate prehensile function in reconstructed bilateral metacarpal hands with acceptable donor-site morbidity.     

Toe‐bud clipping of juvenile small marsupials for ecological field research: No detectable negative effects on growth or survival

Toe clipping is widely used to permanently mark many species of small vertebrates including marsupials, particularly didelphids and dasyurids. Small marsupials are marked as juveniles, by removing the tip of developing toe buds. It has recently been shown that survival and/or recapture probability decreases with increasing number of toes clipped in frogs. Because of this and other animal welfare concerns, toe clipping of adult vertebrates is increasingly being discouraged. The short‐ and long‐term effects of toe‐bud clipping have not been evaluated in marsupials. We used an experiment to test if marking more toes results in slower growth or higher mortality in the brown antechinus (Antechinus stuartii, Dasyuridae) in the short or long term. We found no harmful effects of toe‐bud clipping. There were no infections associated with clipping, marking more toes did not reduce growth in young or adults, and did not affect survival of young in captivity, survival of independent animals in the wild, or recapture probability. Toe‐bud clipping is done at an extremely immature stage, when the area cut is tiny and perception and memory of pain is unlikely to be a problem. We suggest that toe‐bud clipping is a humane and benign method of permanently marking antechinuses, and probably also the young of other morphologically similar small marsupials.     

Anatomy of a duplicated human foot from a limb with fibular dimelia.

At birth, a patient presented with a right lower limb featuring preaxial polydactyly and fibular dimelia with a complete absence of the tibia. Radiographic studies of the patient's foot revealed a duplicated tarsus with eight metatarsals and toes. The three preaxial toes were surgically removed at 1 year of age. A hallux and four normal-appearing postaxial toes remained. The foot was amputated when the patient was 3 years old. Dissection of the amputated foot revealed that the muscles of the dorsum were normal, except that the tendon of the extensor hallucis brevis muscle inserted into both the hallux and toe 2, rather than only into the hallux. The few abnormalities observed among the muscles on the plantar surface of the foot included absence of the insertions of the tibialis posterior and the abductor hallucis muscles. In addition, the two heads of the adductor hallucis muscle inserted abnormally into the medial (tibial) side of metatarsal 1, rather than into the lateral side. These various muscular anomalies, in addition to the mirror duplication of the foot with the presence of only a single metatarsal 1, leads us to propose that this metatarsal probably represents two lateral (fibular) halves that form a laterally duplicated bone. Although the dorsalis pedis artery was present on the dorsal surface of the foot, most of its derivatives were absent. This artery did give rise to a supernumerary medial branch that ended abruptly in the connective tissue (presumably postsurgical scar) at the medial border of the foot. This branch may have represented a duplicated dorsalis pedis artery associated with the duplicated preaxial portion of the foot. The arteries on the plantar surface of the foot were normal. Even though some anomalies in the pattern of the cutaneous innervation were observed, the nerves of the foot were largely normal. The gross and radiographic anatomy of this specimen and the radiographic anatomy of the leg suggest that some teratogenic event occurred when developmental specification reached the level of the future knee. The teratogenic event, which probably occurred early in the fifth week of development, may have caused damage that led to a lateral duplication of both the leg and the foot with the absence of some of the most medial structures. Teratology 60:272-282, 1999.     

Prolongation of skin allograft survival after neonatal injection of donor bone marrow and epidermal cells

Composite-tissue (e.g., hand allograft) allotransplantation is currently limited by the need for immunosuppression to prevent graft rejection. Inducing a state of tolerance in the recipient could potentially eliminate the need for immunosuppression but requires reprogramming of the immunological repertoire of the recipient. Skin is the most antigenic tissue in the body and is consistently refractory to tolerance induction regimens using bone marrow transplantation alone. It was hypothesized that tolerance to skin allografts could be induced in rats by injecting epidermal cells with bone marrow cells during the first 24 hours of life of the recipients. Brown Norway rats (RT1n) served as donors for the epidermal cells, bone marrow cells, and skin grafts. Epidermal cells were injected intraperitoneally and bone marrow cells were injected intravenously into Lewis (RT1l) newborn recipient rats. In control groups, recipients received saline solution with no cells (group I, n = 12), bone marrow cells only (group II, n = 15), or epidermal cells only (group III, n = 15). In the experimental group (group IV, n = 18), recipients received epidermal and bone marrow cells simultaneously. Skin grafts were transplanted from Brown Norway (RT1n) rats to the Lewis (RT1l) rats 8 weeks after cell injections. Skin grafts survived an average of 8.5 days in group I (10 grafts), 9.2 days in group II (12 grafts), and 12 days in group III (14 grafts). Grafts survived 15.5 days (8 to 26 days) in group IV (15 grafts). The difference was statistically significant (p < 0.05). Hair growth was observed in some accepted grafts in group IV but never in the control groups. This is the first report of prolonged survival of skin allografts in a rat model after epidermal and bone marrow cell injections. Survival prolongation was achieved across a major immunological barrier, without irradiation, myeloablation, or immunosuppression. It is concluded that the presentation of skin-specific antigens generated a temporary state of tolerance to the skin in the recipients that could have delayed the rejection of skin allografts.     

Morphological evolution in Tropidurinae squamates: an integrated view along a continuum of ecological settings

Variation in squamate foot morphology is likely relevant during evolutionary processes of habitat colonization because distinct surfaces differ in energetic and functional demands for locomotion. We combined new foot morphological data with published information of limb and tail lengths to investigate evolutionary changes possibly associated with the differential usage of ecological settings by Tropidurinae species. Several traits exhibited significant phylogenetic signal, and we performed conventional and phylogenetic regressions of PC scores (retained from Principal Components Analyses of morphometric traits) on continuous ecological indices. Tropidurines from sandy habitats exhibit larger foot soles, opposite to the evolution of narrow feet in species that use branches and rocks. Also, species that usually move along trunks present longer femora. This study provides evidence for morphological adaptations associated with substrate usage in Tropidurinae, and suggests that opposite morphological profiles might evolve associated with the use of surfaces energetically and functionally contrasting, possibly leading to trade‐offs.     

Sixty-four cases of thumb and finger reconstruction using transplantation of the big toe skin-nail flap combined with the second toe or the second and third toes

The purpose of this article is to introduce the results of thumb and finger reconstruction using transplantation of the big toe wraparound flap combined with the second toe or the second and third toes. Between August of 1981 and December of 1998, in a series of 64 cases involving 58 patients with digitless hands, either (1) the thumb and index fingers were reconstructed by transplantation of a big toe wraparound flap combined with the adjacent second toe harvested from the ipsilateral foot; or (2) the thumb, index, and long fingers were reconstructed by transplantation of an ipsilateral big toe wraparound flap combined with the adjacent second and third toes. The phalanx of the new thumb was usually an iliac block. The success rate of this series was 92.2 percent. At long-term follow-up, the average static 2-point discrimination was less than 10 mm. The distance between the tip of the new thumb and the new index finger ranged from 6 to 10 cm (average, 8 cm). Opposition action was nimble and forceful. The patients could lift a 6- to 12-kg weight with their reconstructed digits. All patients were satisfied with their new hands and were able to use them in their daily activities. The transplants for reconstructing the thumb and fingers are harvested from the same foot in a procedure known as one-foot donation. Function of the bilateral digitless hand can be recovered with this procedure.     

NOTES ON THE HABITS AND STRUCTURE OF THE GUACHARO STEATORNIS CARIPENSIS

1. Steatornis is peculiar, perhaps unique, among birds in possessing two specialized means, one auditory and the other tactile, of locating objects in total darkness.
2. Owing to the peculiar position of the hallux and the fact that the much-abbreviated metatarsus is more or less on the same plane as the toes, the hind limbs are ill-adapted for walking or for perching on a branch, but they afford the bird a secure foothold when resting longitudinally on a ledge.
3. In the embryo the abnormally short metatarsus is incorporated in the body of the foot. Although anatomically distinct in the adult, functionally it remains a part of the foot serving to support much of the bird's weight when resting in its normal crouching posture.     

More than skin and bones: Comparing extraction methods and alternative sources of DNA from avian museum specimens

Next‐generation sequencing has greatly expanded the utility and value of museum collections by revealing specimens as genomic resources. As the field of museum genomics grows, so does the need for extraction methods that maximize DNA yields. For avian museum specimens, the established method of extracting DNA from toe pads works well for most specimens. However, for some specimens, especially those of birds that are very small or very large, toe pads can be a poor source of DNA. In this study, we apply two DNA extraction methods (phenol–chloroform and silica column) to three different sources of DNA (toe pad, skin punch and bone) from 10 historical avian museum specimens. We show that a modified phenol–chloroform protocol yielded significantly more DNA than a silica column protocol (e.g., Qiagen DNeasy Blood & Tissue Kit) across all tissue types. However, extractions using the silica column protocol contained longer fragments on average than those using the phenol–chloroform protocol, probably as a result of loss of small fragments through the silica column. While toe pads yielded more DNA than skin punches and bone fragments, skin punches proved to be a reliable alternative source of DNA and might be especially appealing when toe pad extractions are impractical. Overall, we found that historical bird museum specimens contain substantial amounts of DNA for genomic studies under most extraction scenarios, but that a phenol–chloroform protocol consistently provides the high quantities of DNA required for most current genomic protocols.     

Treatment of lateral ray polydactyly of the foot: focusing on the selection of the toe to be excised

The purposes of this study were to evaluate the results of the operative treatment of lateral ray polydactyly and to consider appropriate surgical procedures, especially focusing on the selection of the toe, lateral toe or medial toe, to be resected. Twenty-two patients with lateral ray polydactyly foot (25 individual feet) at an average of 71 months' follow-up were included in this study. Cases were classified morphologically into three types on the basis of Hirase's configuration. In addition, these types were divided into two subtypes, metatarsal and phalangeal, on the basis of radiographic evaluation of the level of duplication. The clinical evaluations of the reconstructed toe were performed, and these results were investigated according to their morphologic classification and excised toe group. The distinctive problem of medial toe excision is valgus deformity. Eight of 25 toes retained persistent valgus deformity, and all of these cases were in the medial toe excision group. On the other hand, a distinctive problem in lateral toe excision is postoperative pain. Two patients suffered from postoperative pain in phalangeal type cases in the lateral toe excision group, and the remaining medial toe had a medial protuberant middle phalanx. The pain occurred at that protuberant point. Based on their experiences, the authors created an algorithm for selection of the toe to be excised. In metatarsal type cases, from a functional perspective, the toe that has a radiographically dominant metatarsus should be retained. On the other hand, in phalangeal type cases, the authors give priority to shape rather than function, and they excise the morphologically smaller toe independent of the condition of the phalanx as viewed on radiography. If the medial toe and the lateral toe are approximately the same size, the authors excise the lateral toe to avoid valgus deformity. When the lateral toe has severe valgus deformity that seems unlikely to be correctable intraoperatively, the lateral toe should be considered for excision even if it is larger than the medial toe.     

Pedal symphalangism in modern American and Japanese skeletons

Pedal symphalangism is a surprisingly common heritable trait of the human foot. In individuals exhibiting the trait, the joint between the intermediate and distal phalanges of one or more lateral toes never develops, resulting in toes with two phalanges rather than three. This study was undertaken to explore variation in the frequency of pedal symphalangism among groups with widely different geographic ancestry, and to consider the applicability of this trait to skeletal biological distance studies. A total of 460 Euro-American, 191 African-American and 99 Japanese skeletons were examined for presence of pedal symphalangism. The American individuals date to the first half of the 20th c, while the Japanese individuals date to the late 19th and early 20th c. Although the country of ancestry is unknown for most of the American individuals, the Euro-Americans appear to be largely northern European, with roots in Germany, Ireland and Scandinavia, while the African-Americans are primarily descendants of slaves with roots in west African countries such as Nigeria, Benin, Togo, Ghana and Sierra Leone. Frequencies of fifth toe pedal symphalangism were calculated and compared among all three samples and found to be significantly higher in modern Japanese (83.7%) than in either Euro-Americans (46.4%) or African-Americans (44.0%). The Euro- and African-American frequencies were statistically indistinguishable for symphalangism of the fifth toe. In the fourth toe, however, the opposite result was found. The African-American frequency (7.9%) was significantly higher than the Euro-American frequency (2.6%), while no difference was found between the African-Americans and Japanese (11.7%). Since fourth toe pedal symphalangism has never been observed in the absence of fifth toe involvement, some of the same genes are clearly involved in producing the trait in both toes. However, differences in the pattern of fourth and fifth toe expression among the three groups identified in this study suggest that additional genetic or developmental factors may play a role in expression of pedal symphalangism in each of the toes.