SNOMED CT, US Edition

Last uploaded: March 22, 2026
Id http://purl.bioontology.org/ontology/SNOMEDCT/782757004
http://purl.bioontology.org/ontology/SNOMEDCT/782757004
Preferred Name

Congenital microcephaly, severe encephalopathy, progressive cerebral atrophy syndrome

Definitions
A rare, genetic, neurometabolic disorder characterised by severe, progressive microcephaly, severe to profound global development delay, intellectual disability, seizures (typically tonic and/or myoclonic and frequently intractable), hyperekplexia, and axial hypotonia with appendicular spasticity, as well as hyperreflexia, dyskinetic quadriplegia, and abnormal brain morphology (cerebral atrophy with variable additional features including ventriculomegaly, pons and/or cerebellar hypoplasia, simplified gyral pattern and delayed myelination). Cortical blindness, feeding difficulties and respiratory insufficiency may also be associated. A rare genetic neurometabolic disorder with characteristics of severe progressive microcephaly, severe to profound global development delay, intellectual disability, seizures (typically tonic and/or myoclonic and frequently intractable), hyperekplexia and axial hypotonia with appendicular spasticity, as well as hyperreflexia, dyskinetic quadriplegia and abnormal brain morphology (cerebral atrophy with variable additional features including ventriculomegaly, pons and/or cerebellar hypoplasia, simplified gyral pattern and delayed myelination). Cortical blindness, feeding difficulties and respiratory insufficiency may also be associated. There is evidence the disease is caused by homozygous or compound heterozygous mutation in the ASNS gene on chromosome 7q21. A rare, genetic, neurometabolic disorder characterized by severe, progressive microcephaly, severe to profound global development delay, intellectual disability, seizures (typically tonic and/or myoclonic and frequently intractable), hyperekplexia, and axial hypotonia with appendicular spasticity, as well as hyperreflexia, dyskinetic quadriplegia, and abnormal brain morphology (cerebral atrophy with variable additional features including ventriculomegaly, pons and/or cerebellar hypoplasia, simplified gyral pattern and delayed myelination). Cortical blindness, feeding difficulties and respiratory insufficiency may also be associated.
Synonyms
Asparagine synthetase deficiency
Congenital microcephaly, severe encephalopathy, progressive cerebral atrophy syndrome (disorder)
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