Isolated anencephaly/exencephaly

What it is

A rare neural tube defect characterized by the absence of cranial vault and brain structures. This lethal malformation is secondary to a failure to close the anterior neuropore during early embryonic development, leading to exencephaly (''open'' brain). The degeneration of the cerebral tissue is due to their exposure to the amniotic fluid and converts the exencephaly into anencephaly (absence of the brain).

Key facts

Prevalence

1-9 / 1 000 000 (Europe)

Age of onset

Infancy, Neonatal

Inheritance

Multigenic/multifactorial, Not applicable

Classified as

Morphological anomaly

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

Genes reported in subtypes

Orphanet records these genes on 2 more specific entries under this disorder, not on this entry itself:

A well-studied disease is usually split into subtypes, and the gene is curated on whichever one the evidence belongs to. Open a subtype to see which gene goes with it.

ICD-10 codes

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references