hypotonia, infantile, with psychomotor retardation and characteristic facies 3
Findings
No curated finding names hypotonia, infantile, with psychomotor retardation and characteristic facies 3 yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
A rare, genetic, syndromic intellectual disability characterized by usually profound intellectual disability with absent speech, severe infantile hypotonia with decreased or absent reflexes, markedly slow motor development (with no progress beyond the ability to sit independently), early-onset epilepsy, strabismus and post-natal onset of progressive brain atrophy (incl. loss of brain volume, ex vacuo ventriculomegaly, dysgenesis of corpus callosum, white matter abnormalities ranging from non-specific changes to leukodystrophy). Swallowing difficulties, respiratory insufficiency, osteoporosis and variable craniofacial dysmorphisms (incl. plagio/brachicephaly, bitemporal narrowing, high-arched eyebrows, high nasal bridge, anteverted nares, high palate, tented upper lip) may constitute additional clinical features.
Definition from the Mondo Disease Ontology (MONDO:0014823), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Congenital onset · Infantile onset · Neonatal onset
HPO, annotations 2026-09-02
Features
142 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- AcromeliaHPOHP:0010884
- 8 of 8 reported patients
- AreflexiaHPOHP:0001284
- 8 of 8 reported patients
- Frequent (30% to 79% of cases)
- Axial muscle weaknessHPOHP:0003327
- 2 of 2 reported patients
- Bilateral tonic-clonic seizure with focal onsetHPOHP:0007334
- 2 of 2 reported patients
- Delayed skeletal maturationHPOHP:0002750
- 2 of 2 reported patients
- Occasional (5% to 29% of cases)
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- TBCKHGNC:28261
- Definitive · G2P · Autosomal recessive · 2016
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2023
- Strong · PanelApp Australia · Autosomal recessive · 2025
Where it sits
Other names
4 names
Resolves to: hypotonia, infantile, with psychomotor retardation and characteristic facies 3
- Also called
- IHPRF3TBCK ID-syndromeTBCK syndromeTBCK-related encephalopathy