Synonyms: Del(12)(p12.1) | Monosomy 12p12.1
A rare chromosomal anomaly syndrome resulting from the partial deletion of the short arm of chromosome 12 characterized by intellectual disability global developmental delay with prominent language impairment behavioral abnormalities and mild facial dysmorphism (incl. frontal bossing downslanting palpebral fissures epicanthal folds broad depressed nasal bridge with bulbous nasal tip low-set ears with underdeveloped helices). Other associated features may include skeletal abnormalities (butterfly vertebrae scoliosis) strabismus optic nerve hypoplasia and brain malformations.
Data from Orphanet are used to provide information on a disease's name, synonym(s), and overview. Reference: Access aggregated data from Orphanet at Orphadata. Orphadata: Free access data from Orphanet. © INSERM 1999. Available on http://www.orphadata.org. Data version January 2026
Newly diagnosed with
12p12.1 microdeletion syndrome?
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Advocacy Organizations
COMBINEDBrain Inc
COMBINEDBrain is a consortium for outcome measures and biomarkers for neurodevelopmental disorders. We are collaborating to cure rare, non-verbal brain disorders.
DDX3X Foundation
Our mission is to connect families, resources, and the medical community to advance research for a treatment or cure to DDX3X Syndrome. Our ultimate goal is to accelerate brain function in individuals affected by DDX3X Syndrome through advances in cell and gene therapy and pharmaceuticals.
Moonshots for Unicorns
Curing single-gene disorders
Project CASK
VISION Project CASK believes in a world free of the life limitations and debilitating effects of CASK gene disorders. MISSION To accelerate breakthroughs in research to develop treatments and a cure for CASK gene disorders. VALUES Collaboration. Transparency. Urgency.
Rare Chromosome Disorder Support Group – Unique
Through sharing knowledge and lived experience, Unique helps families and professionals navigate the world of chromosome and gene disorders
Syndromes Without A Name (SWAN) Australia
Provide information, support and advocacy to families caring for a child with an undiagnosed or rare genetic condition.
TNPO2 Foundation
Develop personalized therapeutics for ultra rare genetic neurodevelopmental diseases, especially those arising from mutations in the TNPO2 gene.
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Clinical Trials
For a list of clinical trials in this disease area, please click here.