Fetal trimethadione syndrome

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Fetal trimethadione syndrome

ORPHA:1913Malformation syndrome

What it is

A drug-related embryofetopathy that can occur when an embryo/fetus is exposed to trimethadione and that is characterized by pre- and post-natal growth retardation, intellectual deficit, developmental and speech delay, craniofacial anomalies (with some similarities to those seen in fetal valproate syndrome), and less commonly, cleft palate, malformations of the heart, urogenital system and limbs. Trimethadione is an antiepileptic drug that has been removed from the market in Europe and is no longer used much in other countries due to teratogenicity and potential side effects.

Key facts

Age of onset
Antenatal, Neonatal
Inheritance
Not applicable
Classified as
Malformation syndrome

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.

ICD-10 codes

Q86.8filed under a broader ICD-10 category — shared with 16 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.

Cross-references

MESH C537798MONDO 0016009UMLS C0265373

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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