Polyhydramnios-megalencephaly-symptomatic…

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Polyhydramnios-megalencephaly-symptomatic epilepsy syndrome

ORPHA:500533Disease

Also called PMSE syndrome

What it is

A rare genetic neurological disorder characterized by a pregnancy complicated by polyhydramnios, severe intractable epilepsy presenting in infancy, severe hypotonia, decreased muscle mass, global developmental delay, craniofacial dysmorphism (long face, large forehead, peaked eyebrows, broad nasal bridge, hypertelorism, large mouth with thick lips), and macrocephaly due to megalencephaly and hydrocephalus in most patients. Additional features that have been reported include cardiac anomalies like atrial septal defects, diabetes insipidus, and nephrocalcinosis, among others.

Key facts

Prevalence
<1 / 1 000 000
Age of onset
Antenatal, Infancy, Neonatal
Inheritance
Autosomal recessive
Classified as
Disease

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.

Gene

STRADADisease-causing germline mutation(s) (loss of function)

ICD-10 codes

G40.4filed under a broader ICD-10 category — shared with 28 other rare diseases

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.

Benefit programs to look at

Programs whose eligibility touches the same ICD-10 categories. Eligibility is decided by the administering agency, never by this page.

Cross-references

GARD 12913MESH C567020MONDO 0012611OMIM 611087UMLS C1970203

Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.

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