Cases reported "Ectromelia"

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11/17. Origin of abnormality in a human simelian foetus as elucidated by our knowledge of vertebrate development.

    In this paper we attempt to explain the abnormality of a simelian foetus with reference to our present knowledge of vertebrate development. The various developmental defects seem to have a single common origin: the speeding-up of the progression of cell differentiation in the notochord anlage--which is the organization centre of the embryo--during the regression of the Hensen's node. Cell activity involved in the morphogenetic movements in the chordamesoderm probably stopped before it should have. The elongation of the notochord anlage was not completed, resulting in the defective development of the posterior part of the foetus. A number of pairs of posterior trunk somites were not induced. Consequently (1) the pelvic limb buds, whose posterior parts were missing, fused, bringing in further developmental deviations in the limb skeleton and abdominal muscles; (2) there are no vertebrae between the first sacral vertebra and the misshaped coccyx formed by the tail bud. The derivatives of the posterior endoderm (hindgut, bladder and ureters) were not induced either. The cauda equina is deficient. The absence of functional kidneys and the presence of embryonic urinary tubules in the pelvic cysts which are wrapped up by gut epithelium suggest the induction of the metanephric mesenchyme by ectopic endoderm. The speeding-up of differentiation in the notochord anlage also probably resulted in the excessive extension of its anterior region which is the organizer of brain structures. This explains the overdevelopment of the nose and of the neurocranium, and the low position of the ear. A gene mutation as well as a mechanical stress are the possible causes of the abnormal behaviour of the notochord anlage.
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12/17. Vascular steal: the pathogenetic mechanism producing sirenomelia and associated defects of the viscera and soft tissues.

    dissection of the abdominal vasculature in 11 cases of sirenomelia has demonstrated a pattern of vascular abnormalities that explains the defects usually found in this condition. The common feature is the presence of a single large artery, arising from high in the abdominal cavity, which assumes the function of the umbilical arteries and diverts nutrients from the caudal end of the embryo distal to the level of its origin. The steal vessel derives from the vitelline artery complex, an early embryonic vascular network that supplies the yolk sac. Arteries below the level of this steal vessel are underdeveloped and tissues dependent upon them for nutrient supply fail to develop, are malformed, or arrest in some incomplete stage. In contrast to the prevailing view that sirenomelia arises by posterior fusion of the two developing lower limbs, these studies suggest that the single lower extremity in sirenomelia arises from failure of the lower limb bud field to be cleaved into two lateral masses by an intervening allantois.
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13/17. Sirenomelia. Angiographic demonstration of vascular anomalies.

    A 1,730-g infant with severe caudal regression syndrome (sirenomelia) died shortly after delivery, after a 34-week gestation. autopsy findings included multiple skeletal anomalies, renal agenesis, amnion nodosum, and a single lower extremity. Postmortem arteriography demonstrated a persistent vitelline artery and documented the vascular pattern within the lower extremity. To our knowledge, angiographic demonstration of the lower limb vascularity has not been described previously in sirenomelia. The angiographic findings support the pathogenetic concept of limb bud fusion and malrotation of the limb in sirenomelia after damage to the posterior axis mesoderm in early embryonic life. Postmortem arteriography is an inexpensive, retrievable, and easy means of documenting vascular anomalies in the fetus or infant with multiple congenital abnormalities.
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14/17. A fetus with upper limb amelia, "caudal regression" and Dandy-Walker defect with an insulin-dependent diabetic mother.

    We describe the fetus delivered to an insulin-dependent diabetic woman who had had a previous large, stillborn, non-malformed male infant and a normal female infant. The present fetus had a most unusual combination of malformations which to date had not been described in diabetic embryopathy. The anomalies include: upper limb amelia, "caudal regression" with bilateral absence of the fibulae, unilateral absence of a femur and ipsilateral oligodactyly; undescended testes; atrial septal defect; multiple vertebral and rib anomalies with cervical scoliosis and right webbed neck; left cleft lip and cleft palate; severe micrognathia; left microtia with atresia of the ear canal; and central nervous system defects including hydrocephalus with the Dandy-Walker malformation, asymmetry of the lateral ventricles, abnormal frontal gyral formation, and ependymal and ganglion cell heterotopias of the spinal cord. The pathogenesis of diabetic embryopathy is discussed.
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15/17. Mobius sequence: further in vivo support for the subclavian artery supply disruption sequence.

    Mobius sequence consists of a congenital bilateral facial nerve palsy and external ophthalmoplegia often associated with malformations of the limbs and orofacial structures. The pathogenesis of the sequence is a subject of debate. However, a new hypothesis proposes that Mobius sequence results from an interruption of embryonic blood supply (subclavian artery supply disruption sequence). Here we present an infant with bilateral facial nerve palsy (VII), external ophthalmoplegia (IV, VI), paresis of cranial nerves V, IX, X, XI, and XII, absence of the pectoralis major muscle (poland anomaly), terminal transverse limb defects, and absence of the right diaphragm. Also, he was found to have discrete foci of brainstem calcifications in the region of the dorsal respiratory group on both CT scan and the histologic sections with microscopic evidence of diffuse brainstem "injury." The anomalies and histopathology noted in this infant imply that vascular insufficiency prior to the sixth week of gestation involving the proximal sixth intersegmental artery may result in the manifestations presented in this report and lend further support for the existence of a subclavian artery supply disruption sequence.
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16/17. A case of ambiguous genitalia with unilateral amelia and unilateral peromelia of the upper limbs.

    A 7-year-old patient is reported with a 46,XY karyotype, ambiguous genitalia and unilateral amelia and unilateral peromelia of the upper limbs. The external genitalia had essentially a female configuration with labia majora, large clitoris, and narrow vaginal opening. Gonadal tissue was not palpable on either side. The levels of 17-OH progesterone dehydroepiandrosterone sulfate (DHEA-S), androstenedione and luteinizing hormone (LH) were normal, but the level of follicle stimulating hormone (FSH) was elevated minimally. Abdominal ultrasonography (USG) was normal. On pelvic USG, neither uterus nor ovaries were seen. Genitography showed a blind vagina. gonads, Mullerian and/or Wolffian structures were not observed at laparotomy. Clitoral recession and cut-back vaginoplasty were performed. The occurrence of these findings suggests embryonic testicular regression syndrome with bilateral transverse defect of the upper limbs. The case has been presented because the pattern of the birth defects, including both ambiguous genitalia and unilateral amelia on one side of the upper limbs and unilateral peromelia on the other, have not been described previously.
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17/17. Splenogonadal fusion with limb deficiency and micrognathia.

    Splenogonadal fusion (SGF) is a rare abnormality with two known types. In the continuous type, the spleen is connected to the gonad, and there are often limb defects, micrognathia, or other congenital malformations such as ventricular septal defect, anal atresia, microgastria, spina bifida, craniosynostosis, thoracopagus, diaphragmatic hernia, hypoplastic lung and abnormal lung fissures, polymicrogyria, deficient coccyx, and bifid spine C6-T3. The discontinuous type is usually not associated with congenital defects, and the gonad that fused with an accessory spleen has no connection with the native spleen. The etiology of SGF is not known. Conceivably, a teratogenic insult occurring between 5 weeks' and 8 weeks' gestation could interfere with the normal development of the spleen, gonads, and limb buds. We describe a case of splenogonadal fusion in a stillborn black boy with associated micrognathia and limb deformities. Also, we review the possible teratogenic etiologies and embryonic basis of SGF.
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