Familial developmental dysphasia

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Familial developmental dysphasia

ORPHA:1799Clinical syndrome

Also called Billard-Toutain-Maheut syndrome · FOXP2-associated dysphasia

What it is

Familial developmental dysphasia is a severe form of developmental verbal apraxia characterized by a deficit in spontaneous speech, writing, grammatical judgment and repetition, defective articulation, moderate to severe degree of dyspraxia, a reduced use of consonant clusters, and comprehension delay. Hearing and intelligence are normal.

Key facts

Prevalence
<1 / 1 000 000
Age of onset
Childhood
Inheritance
Autosomal dominant
Classified as
Clinical 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.

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

F80.1filed under a broader ICD-10 category

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 1823MESH C563997MONDO 0010821OMIM 600117UMLS C1838630

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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