China
Africa
Explore chapters and articles related to this topic
Assessment of fetal brain abnormalities
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Holoprosencephalies are classified into three varieties: alobar, semilobar, and lobar types. Facial abnormalities such as cyclopia, ethmocephaly, cebocephaly, flat nose, cleft lip, and palate are invariably associated with holoprosencephaly and extracerebral abnormalities. Facial abnormalities are often associated with holoprosencephaly.
Central nervous system: Paediatric and neurodevelopmental disorders
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
In holoprosencephaly there is a variable failure of development of the forebrain with associated facial features. It is usually lethal, especially the extreme forms of cebocephaly and cyclopia. More minor forms may occur though; an external indicator may be the presence of fused central incisor teeth (the ‘single central incisor’). The condition may be isolated, or it may be part of trisomy 13. Apart from Meckel syndrome (see earlier), other cases of autosomal recessive inheritance have been reported, as well as occasional dominant inheritance with a very mildly affected parent, so caution, chromosome analysis and thorough pathology after death are needed. The frequency is considerably increased in maternal diabetes. The recurrence risk after an isolated non-syndromal case is relatively low (4%–5%). The human counterpart of a specific Drosophila developmental gene (SHH on chromosome 7q) shows mutations in some dominantly inherited cases.
Growth of the Orbit
Published in D. Dixon Andrew, A.N. Hoyte David, Ronning Olli, Fundamentals of Craniofacial Growth, 2017
Some of the grossest orbital malformations occur in holoprosencephaly. “In alobar prosencephaly, the embryonic forebrain fails to cleave sagittally into cerebral hemispheres, transversely into telencephalon and diencephalon, and horizontally into olfactory and optic bulbs” (Cohen, 1986). There may result the single median orbit of cyclopia, with or without a tubular proboscis above, with eye development varying from anophthalmia, or monophthalmia to synophthalmia; ethmocephaly with hypotelorism and absent nose; or premaxillary agenesis, again with hypotelorism, which also occurs in cebocephaly where there is a single nostril nose (Cohen et al. in Bergsma, 1971; Cohen and Sulik, 1992). Currarino and Silverman (1960) and Silverman (1965) described hypotelorism in association with trigonocephaly and arrhinen-cephaly (part of the spectrum of holoprosencephaly). McGrath (1989, 1992) and McGrath and Sperber (1990) gave detailed descriptions of the structure and contents of the median orbit in human cyclopia. In the absence of some nasal structures — mesethmoid (crista galli, perpendicular plate of the ethmoid and adjacent portion of the cribriform plate), nasal septum, and vomer — and parts of the medial walls of the orbits, the frontais approach each other above the single cavity, and the maxillae fuse below to form a floor, which also incorporates the lacrimal and palatine bones, and which extends further backwards than normal because the presphenoid is absent. The ectethmoid conchae do develop.
Dinosaur Tail Appendix in Trisomy 13
Published in Fetal and Pediatric Pathology, 2022
Mădălina Boșoteanu, Cristian Ionuț Orășanu, Mariana Așchie, Mariana Deacu, Georgeta Camelia Cozaru, Costel Brînzan, Anca Florentina Mitroi
This 38-week gestational age female with full trisomy 13 died at 19 days of age. In addition to the more commonly described morphologic abnormalities (growth restriction - birth weight of 2100 g, cebocephaly, ocular hypotelorism, single nostril, microphthalmia, flat nasal bridge, keilognatopalatoschizis, micrognathia, low-set ears, postaxial polydactyly of feet and hands, single palmar transverse crease, rocker-bottom feet, closed fontanels, hypogyria, lobar holoprosencephaly, single cerebral ventricle), there was a dinosaur-tailed appendix (Fig. 1).