Definition: Anencephaly is a designation for congenital absence of the cranial vault with cerebral hemispheres completely missing or decreased to small masses attached to the base of the skull. In anencephaly, the absence of the brain and calvaria can be total or partial. Anencephaly is one of the neural tube defects (NTDs).
The etiology is unknown. Whether the bony tissue or soft brain tissue is a primary factor is also unknown.
Synopsis
congenital absence of the cranial vault
cerebral hemispheres completely missing or decreased to small masses attached to the base of the skull
The absence of the brain can be total or partial.
The absence of thecalvaria can be total (acrania) or partial.
bactracian facial dysmorphism
absent frontal bones
shallow orbits
protusion of the eyeballs
Types
isolated anencephaly
- sporadic anencephaly
- familial anencephaly
syndromal anencephaly
- associated anencephaly (see Associations)
holoacrania form of anencephaly
Associations
bilateral adrenal hypoplasia
cardiac malformations
- aortic coarctation
- left heart hypoplasia (left ventricular hypoplasia)
cleft lip/palate
spina bifida
complete rachischisis
short-rib polydactyly syndrome (SRPS) (8267012)
congenital diaphragmatic hernia
macrosomia
cystic renal dysplasia
Etiology
sporadic
familial anencephaly (2333913)
- parental consanguinity (2333913)
NB: Posterior fossa
A study showed 2 morphologic types of the posterior cranial fossa. One type had a fossa cranial morphology close to normal morphology, whereas the other had a malformed and much smaller posterior cranial fossa. The latter condition was presumed to be due to a primary error in chondral and cranial development. (15630528)
See also
cerebral malformations
neural tube defects (NTDs)
Animal models
mice that are homozygous for deficiency in the paired class homeobox-containing gene Cart1
References
Lomholt JF, Fischer-Hansen B, Keeling JW, Reintoft I, Kjaer I. Subclassification of anencephalic human fetuses according to morphology of the posterior cranial fossa. Pediatr Dev Pathol. 2004 Nov-Dec;7(6):601-6. Epub 2004 Nov 17. PMID: 15630528
