58 A. C. STEVENSON AND OTHERS

12. MALFORMATIONS OF THE LIMBS AND EXTREMITIES (J1-J7)

In many ways it is unrealistic to consider limb As already indicated it seems likely that those malformations in isolation, because the more care- classifiable on recorded descriptions as Jl represent fully many of them are examined, the higher is the only a minority of all cases of ulnar polydactyly. proportion that can be shown to be only the most On the other hand, J3 is a heterogeneous group. obvious manifestation of a disturbance elsewhere At a guess perhaps two-thirds of cases in J3 are and in particular of the development of the skeleton ulnar polydactyly but some are of lateral polydactyly as a whole. Nevertheless, there are a series of dis- of feet or of hands and feet while others may be of turbances confined to or mainly manifest in the uncommon types involving duplication or partial limbs or only in the hands and feet. Of those, at duplication of the middle digits. least half are manifest predominantly as anomalies There is no significant correlation at a 5 % level of the fingers or toes. Many of these anomalies are between the frequencies of JI and J3 (r = + 0.039). not of much importance to the individual, but they However, this is not necessarily in conflict with the are of considerable interest in the context of embryo- remarks above, if as is almost certainly true, in logy and human biology. some centres most cases of ulnar polydactyly were recorded and therefore grouped by the authors as Jl, while in other centres the same condition was POLYDACTYLY (Jl-J3) IN SINGLE BIRTHS simply called " polydactyly " or " hexadactyly " and grouped by the writers as J3. In view of what is In most parts of the world the commonest known, in spite of the absence of correlation of fre- individual malformation of the extremities is an quencies, it seems justifiable to group Jl and J3 for extra finger or an extra toe or both, although extra some purposes. fingers outnumber the sum of the other two. Diffe- the Ulnar polydactyly has long been recognized to be rentiation of the hand buds is earlier than that of very frequent in Africans. In this study the highest foot, and it is not surprising that polydactyly of of frequencies of Jl are in Pretoria (4.79 per 1000), hand and feet frequently occur independently where the patients were all Bantu, and in Sao Paulo each other as well as together. Most of this poly- African con- ulnar (2.63 per 1000), where there is a large dactyly is determined by an extra digit on the tribution to the ethnic mixture of many of the side of the hand, varying from a more or less com- mothers. In Pretoria the frequency of J3 was also plete digit with nail formation to a rudimentary relatively high. In Panama, where there is also a finger with or without cartilage or a centre of ossi- there were no reported Answers to large African contribution, fication to only a small skin tag. ques- cases described as ulnar polydactyly, but the fre- tions sent to organizers at various centres subsequent in other centre. make it clear that it is quency of J3 was twice as high as any to completion of recording From subsequent inquiry it is clear that virtually all this type of malformation which is probably present " cases really were of ulnar polydactyly. From the in most cases grouped as J3, where polydactyly" to " " was above it will be clear that it is not possible judge without further description or hexadactyly the real frequencies of ulnar polydactyly, but that recorded. the figures for Ji are minimal and those for JI + J3 maximal as estimates of frequencies. Polydactyly grouped as Jl and J3 Most cases of JI or J3 are sporadic, i.e., occur in In the complete form of ulnar polydactyly there only one individual in a family, and the nature of is usually a bony spur on the fifth metacarpal below any genetical contribution is unknown. In addition, the metacarpo-phalangeal joint. In other cases there in many families ulnar polydactyly appears to be is simply a spur on the fifth metacarpal and/or a inherited by a simple dominant gene mechanism rudimentary finger, a skin tag or even a dimple where although the condition may not be present in all such a skin tag could have originated. The data who are heterozygous for the gene and the manifesta- from the study relative to these conditions are dis- tion is very variable in those affected. It is sometimes played in Table 12.1 said, presumably on the basis of sporadic cases and CONGENITAL MALFORMATIONS 59 the occasional occurrence in sibs although neither SYNDACTYLY (J4) parent is affected, that there is a type determined by a recessive gene mutation. There is no support for The syndactylies are a complex group. When only such a hypothesis from the present data in that there two fingers or toes are involved the term is used to appears to be no connexion with consanguinity. include simple webbing at the bases of the digits, There is no suggestion of any increase in parental fusion of the complete digit except for the bones and consanguinity in parents of children with polydactyly what is more properly called symphalangy, where JI andJ3. there is bony fusion. Such relatively minor mal- formations are quite common and indeed some JJ and J3 as one of two or more malformations degree of webbing of second and third, or third and Polydactyly occurs as part of a remarkable number fourth toes is so common as hardly to be termed of syndromes determined by single genes (for abnormal. example, Lawrence-Moon-Biedl syndrome, chondro- The term is also applied, however, to conditions ectodermal dysplasia and syndromes of the Pierre involving considerable degrees of disorganization of Robin type), and in those determined by chromo- the hand merging into ectrodactyly and often even somal abnormalities (e.g., Down's syndrome, tri- in lesser degrees than that, but involving absence of somy 14/15). It also occurs as one malformation in another digit. Thus Apert's syndrome is often many infants with multiple malformations where the termed acrocephaly-syndactyly but the syndactyly genetical contribution to etiology, if any, is complex. is really a disorganization of the hand, almost In all these the polydactyly is almost invariably ulnar invariably involving the metacarpals as well as the or lateral on the feet. Ulnar polydactyly occurs in phalanges. Such information as was recorded other 25 cases in the N group (7.6%) and there are five than simply syndactyly is set out in the lists of cases in that group where there was polydactyly malformations in the Basic Tabulations by Centres (presumably lateral of both hands and feet). booklet. Both major and minor types of syndactyly occur in some families in a pattern suggesting a single POLYDACTYLY, RADIAL (J2) dominant gene hypothesis, and in others as sporadic cases or with a lower familial concentration than "Radial polydactyly " is strictly a misnomer. compatible with simple Mendelian inheritance. In the great majority of cases the condition is There is no means of making such distinctions from simply a duplication of the terminal phalanx of the the study data. thumb. A similar condition is found in the great toes. Syndactyly also occurs in 10 infants as one of This malformation is much less common in most multiple malformations, as is clear from the data centres than the ulnar types of polydactyly. Some- considered in section 16. In view of the heterogeneity times only the nail is duplex or there is only incom- of types and etiology and particularly in view of the plete duplication of the terminal phalanx. As will be low over-all frequency (0.15 per 1000 single total seen from Table 12.1, this condition is less common births), little can be deduced from Table 12.2. than Jl and, although a few cases may have been included in J3, it is unlikely that such cases would be described only as polydactyly. Radial polydactyly OTHER DIGITAL ANOMALIES (J5) appears to be more common in Hong Kong (0.91 per 1000 total single births) and Singapore (0.50 per 1000 This is an extremely heterogeneous group, as may single births) than elsewhere. In Singapore 19 of be seen from the lists of malformations. There is 20 cases had Chinese mothers; one was born to an virtually no limit to the variety of anomalies of dif- Eurasian. The frequency in Chinese in Singapore is ferentiation of the digits, so that the various com- 0.60 per 1000. All four cases in Kuala Lumpur were binations of polydactyly, brachydactyly, syndactyly, Chinese-a frequency of 0.46 per 1000. Thus the symphalangy and absence of digits cannot be clas- three highest frequencies are in children of Chinese sified in any adequate way. As with other anomalies mothers, which is suggestive. Over all the centres the of number and conformation of digits, these ano- correlation of the frequencies Ji +J3 and J2 is malies occur as one of several in the same child. negative (r= -0.237). There were six cases where J2 In this series one of this group was recorded in was one of the malformations in the N group. 15 cases in the N group (4.5%). 60 A. C. STEVENSON AND OTHERS

REDUCTION DEFORMITIES OF LIMBS (J6) 1000) from Manila, but the cases appeared not to be of any particular pattern but of all types included in There has in recent years been much interest in this group. There were eight malformed children reduction deformities of limbs since the tragic classified to the N group in whom a reduction sequelae of the use of thalidomide in the treatment deformity of limbs was one of the malformations. of early sickness in pregnancy. However, cases which are indistinguishable occur " spontaneously " and there are many varieties of malformation not "OTHER LIMB DEFORMITIES (J7) encountered in thalidomide cases which are con- veniently termed reduction deformities. As mentioned above, individual cases posed the It is very difficult to decide what to include in such problem of grouping in J6 or J7. Radio-ulnar a group apart from so-called " congenital amputa- " dysostosis ", " agenesis " or " dysplasia " or Made- tions ". Any extremities found on reduced or lung's deformity were included in this group, as rudimentary limbs are invariably malformed. If were a large variety of conditions such as genu there is agenesis of the radius the ulna is also usually recurvatum and absence of patella. Also included short and the radial side of the hand is malformed. were such conditions as ectrodactyly, genu valgum, Should these conditions be included? As used here, flail joints; and odd cases where two or more limb the term includes absence of any part of a limb, e.g., malformations appeared in the same child were even a single finger, and it also includes localized retained in this group rather than transferred to brachydactyly. Such terms as " rudimentary arms ", group N. A considerable proportion of the variation " agenesis hand ", " reduction deformity of . . . of numbers between centres is accounted for by " phocomelia ", etc., also determined the placing of " genu recurvatum ". the case in the J6 category. However, it was very Twenty-nine cases where one deformity would difficult to decide how to classify many cases. This have determined grouping in J7 have, because there heterogeneous group has a higher frequency than were other malformations, been placed in the N those in the J4 and J5 group (over-all, 0.21 per 1000 group, and some in which other malformations were total single births). There were 15 cases (0.51 per skeletal have been placed in the K5 group. CONGENITAL MALFORMATIONS 61

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