Timothy syndrome

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Timothy syndrome

ORPHA:65283Malformation syndrome

Also called LQT8 · Long QT syndrome type 8 · Long QT syndrome-syndactyly syndrome

What it is

A rare multiple congenital anomalies syndrome with cardiac involvement as a major feature characterized by QT prolongation, congenital heart defects, syndactyly, facial dysmorphism and neurodevelopmental features. There are three clinical phenotypes recognized, the classical types that present with a prolonged QT interval and either with (TS1) or without (TS2) cutaneous syndactyly of fingers and toes. The atypical form (ATS) causes multi-system health concerns but not necessarily with prolonged QT.

Key facts

Prevalence
<1 / 1 000 000
Age of onset
Antenatal, Neonatal
Inheritance
Autosomal dominant
Classified as
Malformation syndrome

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.

Genes reported in subtypes

CACNA1C

Orphanet records this gene on 3 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

I49.8filed under a broader ICD-10 category — shared with 7 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

GARD 9294MEDDRA 10079205MESH C536962MONDO 0010979OMIM 601005OMIM 618447UMLS C1832916

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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