Paper - An unusual form of brachyphalangy and syndactyly with double proximal phalanx in the middle fingers (1932)
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Cockayne EA. An unusual form of brachyphalangy and syndactyly, with double proximal phalanx in the middle fingers. (1932) J Anat. 67: 165-167. PMID 17104406
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An Unusual Form of Brachyphalangy and Syndactyly, with Double Proximal Phalanx in the Middle Fingers
By E. A. Cockayne, D.M., F.R.C.P.
R.J., the boy with the abnormality, was brought to the Hospital for Sick Children, Great Ormond Street, in October, 1931. He was then aged 8 months, the only child of first cousins, who are English and live at Watford. His mother says that as far as she knows no similar deformity has been present in any other member of the family. The boy appears to be of normal intelligence, but is small for his age, weighing 10 lb. 5 oz. at 18 months, and has a harsh systolic . murmur, which is loudest over the lower part of the sternum and is probably due to a patent interventricular septum.
In each hand the index finger is very short and sharply bent in the middle so that the distal end points towards the middle finger. There is complete syndactyly of the middle and ring fingers of each hand, but the union is confined to the soft tissues and the nails are not joined together, and each middle finger is reduced in length so that it is shorter than the ring finger. A skiagram taken in October shows that in both index fingers the middle phalanx is represented by.a minute spherical bone, and the proximal phalanx is very small, misshapen, and much shortened in the right hand and shortened to a less extent in the left. In the middle finger of the right hand the proximal phalanx is represented by five small bones, of which three lie in the long axis of the finger on its radial side, the middle one being considerably the largest, and the other two lie close together at the same level on its ulnar side. In the left hand the proximal phalanx of the middle finger is represented by two small bones, one of which lies on its radial side in the same position as the three bones in the middle finger of the opposite hand, and the other lies on its ulnar side. These bones are all very small, and even combined their mass would be much less than that of a normal proximal phalanx. The proximal phalanx of the left ring finger is considerably shorter than that of the right one, which appears to be of normal length, and the middle phalanx of both little fingers is reduced in length. There is a bifurcation of the ungual phalanx of the index finger of the left hand, an anomaly mentioned by Cunningham, and a similar bifurcation appears to be present in the other index, but the phalanx is very slender.
In the feet there is no syndactyly and no visible deformity, but the skiagrams show that the middle phalanx of both second toes is absent. Only two bones are present in each little toe, but this is probably normal, as the proximal and middle phalanges are often fused.
Skiagrams taken on 25 February, 1982, when the boy was 13 months old, show the arrangement of the abnormal bones more clearly. In the right hand the proximal phalanx of the middle finger appears to be replaced by three bones on the radial side, the largest of which articulates with the middle phalanx and three on the ulnar side. The latter group is very little further away from the metacarpal than the most proximal of the radial group and much nearer to it than the two others belonging to the radial group. In the left hand there are two groups of very small bones replacing the proximal phalanx of the middle finger, but it is difficult to be sure whether there are three in each group or only two, though I think there are three. The position of those on the ulnar side corresponds in the two hands, but on the radial side the group in the left hand is intermediate in position between the two nearest to the middle phalanx and the one nearest to the metacarpal in the right hand.
I have never met this form of brachyphalangy before, nor have I seen any published description of it. In some respects it resembles the condition described by Drinkwater under the title “Hereditary Abnormal Segmentation of the Index and Middle Fingers.” In this there is remarkable reduction in the length of the index and middle fingers and the middle phalanx of the index is aborted. In the index there is a bone of approximately the same length as the proximal phalanx lying between it and the head of the second metacarpal and. becoming fused with the proximal phalanx in adult life, and in the middle finger a triangular bone is interposed on the radial side between the proximal phalanx and the head of the third metacarpal and becomes fused with the phalanx in later life. Drinkwater regards these bones as extra bones arising from an abnormal division of the primitive mesenchyme. Though different in position they may be compared with the extra bones in the position of the proximal phalanx of the middle fingers of my patient. These are looked upon by Dr Bertram Shires, to whom I am indebted for the skiagrams, as extra bones, and he thinks that there is a double phalanx. If so the cause is probably another kind of abnormal division of the mesenchyme in early embryonic life. Drinkwater’s patients had no syndactyly, the feet showed ordinary brachydactyly, the abnormality was inherited as a simple dominant, and so the condition differed in all these three respects from that present in my patient.
Olaf Thomsen has described as the Vordingborg type a syndactyly of the middle and ring fingers with partial or complete doubling of the middle fingers. In some cases the middle phalanx and in others the third metacarpal is branched and all the parts distal to the bifurcation are doubled. Sometimes, however, instead of a simple branching of the metacarpal there is an isolated bone opposite the base of the branched phalanx or the head of the single metacarpal and this bone probably represents part of an extra metacarpal. The condition agrees with that seen in my patient in the association of syndactyly with reduplication of parts, but the reduplication is much more complete and different in character. It differs in the absence of brachyphalangy and in its mode of inheritance. Males are affected more often than females, and up to the present _time it has been transmitted only by males. It is evidently a dominant.
Though differing in minor points the defects in the hands and feet of this boy are in the main symmetrical and this bilateral symmetry makes it almost certain that the abnormality is genetic in origin. It is indeed common to find much greater asymmetry in inherited osseous defects of the extremities. A number of distinct forms of brachyphalangy and of syndactyly occurring either alone or in combination have been described, but with one exception all those with which I am acquainted are autosomal dominants. The one exception is the form of syndactyly described by Schofield, which is transmitted by males only to all their sons and is probably due to a gene in the Y-chromosome. Since the parents of this boy are normal the defect cannot be dominant unless it arose as anew mutation, but it may be recessive, and the fact that the parents are first cousins makes this very probable.
For whereas amongst the general population the percentage of marriages between first cousins is on the average 0-5-1 per cent., in the case of those that give rise to one or more children with a recessive defect the percentage rises from 17 in the case of a relatively common one, such as albinism, to 50 or more, and the rarer the defect the higher is the percentage of first cousin marriages giving rise to it. Thus the high percentage of first cousin marriages in the parents is the most reliable indication that a defect is recessive. Though no safe deduction can be drawn from a single case, we have here a rare defect apparently of genetic origin in the child of first cousins, and the suspicion at once arises that it may be recessive. The case is therefore worth recording, for it is only by publishing descriptions of single cases with full family histories that the mode of inheritance of rare recessive abnormalities can be proved. No single observer can hope to see enough cases himself, but if single cases are published sufficient data can be collected from the literature in course of time, and I hope this short paper will lead to the publication of other cases of the same kind.
Drinkwater, H. (1915-16). J. Anat. and Physiol. vol. u, p. 177.
TxomseEn, O. (1926-7). Acta Scandinavica, vol. Lxv, p. 609; vol. LxvI, p. 588.
Cite this page: Hill, M.A. (2021, June 13) Embryology Paper - An unusual form of brachyphalangy and syndactyly with double proximal phalanx in the middle fingers (1932). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_An_unusual_form_of_brachyphalangy_and_syndactyly_with_double_proximal_phalanx_in_the_middle_fingers_(1932)
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