A rare partial autosomal trisomy/tetrasomy characterized by facial dysmorphism (long thin face prominent forehead down-slanting palpebral fissures prominent nose with broad nasal bridge prominent chin) pre- and postnatal overgrowth renal anomalies (e.g. horseshoe kidney renal agenesis hydronephrosis) mild to severe learning difficulties and behavioral abnormalities. Additional features may include craniosynostosis and macrocephaly.
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 May 2026
Newly diagnosed with
15q overgrowth syndrome?
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Advocacy Organizations
PPP2CA Pathways
PPP2CA Pathways connects families, shares strength, and supports the research community in the search for answers to Houge-Janssens Syndrome type 3.
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
ReNU2 United
ReNU2 United fosters collaboration, supports families, raises awareness, and advances research into RNU2-2-related neurodevelopmental disease.
Uganda Alliance of Patients Organization
Supporting patients to access quality, safe and patient-centered healthcare services.
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Clinical Trials
For a list of clinical trials in this disease area, please click here.