CLCN3-related neurodevelopmental disorder is a very rare condition that affects brain development. So far, only about 11 people have been reported with this diagnosis in medical research.
The most common features are delayed development and intellectual disability.
Other possible symptoms can include:
• Changes in brain structure seen on scans
• Seizures (epilepsy)
• Vision problems
• Decreased muscle tone or “floppiness”
• Behavior or mood problems
• Differences in facial appearance
This condition is caused by changes (variants) in a gene called CLCN3, which normally helps brain cells work properly. The way the condition shows up can depend on the type of gene change:
If a child inherits the same faulty gene from both parents (a homozygous change), symptoms are usually more severe. These children may show more brain shrinkage, smaller brain connections (corpus callosum), and less white matter.
If the gene change happens by chance in one copy of the gene (a de novo change, meaning it is new and not inherited), symptoms can be milder or more varied. These children may also show differences in brain development such as missing or smaller brain structures.
Because the condition is newly discovered, doctors are still learning about the full range of symptoms and how the disorder progresses over time.
CLCN3