A morpho-etiological description of congenital limb anomalies

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CONGENITAL LIMB ANOMALIESFigure 1. Limb anomalies due to fetal causes (chromosomalaberrations).a) Bilateral cutaneous syndactyly of the little and ring fingers(arrow) and right little finger clinodactyly (arrow) in a short broadhand of a Down syndrome child (trisomy 21).b) Left preaxial polydactyly (arrow) in a newborn male withEdward’s syndrome (trisomy 18). Note the malformed low-set andposteriorly rotated ears, the micrognathia, the clenched hand,and the overlapping fingers.c) Left postaxial polydactyly (arrow) in a newborn male withpartial trisomy 13 (13q+). Other dysmorphic features includebulging forehead, blepharophimosis, deep-set eyes, depressednasal bridge, long philtrum, thin upper lip, and pectus excavatum.Figure 2. Showing limb anomalies due to fetal causes (singlegene disorders).a) Triphalangeal and distally displaced left thumb (short arrow)with thenar muscles hypoplasia, and preaxial polydactyly (longarrow) in an infant with the autosomal dominant triphalangealthumb polydactyly syndrome.b) Isolated preaxial polydactyly (arrow).c) Bilateral preaxial autosomal dominant synpolydactyly. Thesecond toe is duplicated and fused (arrows).224Ann Saudi Med 25(3) May-June 2005 www.kfshrc.edu.sa/annals
CONGENITAL LIMB ANOMALIEScases with Poland sequence and classified the handanomalies into seven types according to severity ofthe deformity. Sirenomelia (vitelline artery steal) isanother example of vascular disruption leading toabnormal caudal development. 24 Five cases (7.1%) inthe present study suffered from limb anomalies dueto vascular disruption in the embryonic blood vessels.Vascular anastomoses and discordant placental bloodflow in twins with a common placenta predisposethem to vascular disruptions. In approximately 1%of monozygotic twins, intrauterine death of one twinmay result in release of thromboplastin or emboli tothe surviving co-twin leading to ischemia in localizedareas. 17 One patient in the present study hadgangrene and muscle atrophy of both lower limbs.He was one of a triplet. Other causes of vasculardisruption include placental infarction, maternal hypotension,vasoactive drugs, agents like cocaine andcertain medications. 17 e prenatal diagnostic technique,chorionic villus sampling (CVS), has also beenassociated with limb reduction defect, with anoxia ofdistal fetal structures as a postulated etiology. 39Infants of diabetic mothers have 6% risk of developingcongenital malformations. e risk maybe over 20% if there is poor control during thefirst trimester. e malformations involve the heart(transposition of great vessels), anencephaly, spinabifida, holoprosencephaly, cleft lip and/or palate, renalanomalies and caudal regression sequence. 17 Onecase with caudal regression in the present study wasan infant of an uncontrolled diabetic mother.Twenty cases (28.6%) in the present study hadlimb anomalies as one of the manifestations of sporadicsyndromes (syndromes with unknown etiology).Acheiria (rudimentary hand and fingers) andaphalangia (transverse limb anomalies) are probablycaused by death of the mesenchymal cells in the limbbud region. 40 Ruiter et al 41 have described absent lefthand (a terminal transverse reduction defect) in aboy with mosaic trisomy 22. ey observed that thistype of limb anomalies has never been reported inassociation with this chromosomal aberration. isfinding points out the importance of genetics in thework-up in sporadic cases of limb anomalies.Watson 42 stressed that management of congenitallimb anomalies has to include classificationand etiology, incidence, diagnosis before birth,and counseling of parents. In a similar study doneby Holder-Espinasse et al 43 on 107 cases of limbanomalies, the diagnosis was made in 78%, includingisolated, syndromic, or chromosomal anomalieswith the conclusion that prenatal multidisciplinaryFigure 3 (a,b). Limb anomalies due to fetal causes (single genedisorders).A newborn boy with bilateral postaxial synpolydactyly of the ringfinger (short arrows) and bilateral preaxial synpolydactyly of thebig toe (long arrow).Figure 4 (a,b). Limb anomalies due to environmental causes.Limb anomalies due to amniotic band disruption: a) constrictionrings (arrow), syndactyly, and ectrodactyly or terminal phalangesamputations; b) Transverse limb defect, i.e. amputation of both feet.Ann Saudi Med 25(3) May-June 2005 www.kfshrc.edu.sa/annals 225
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A morpho-etiological description of congenital limb anomalies

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