What is Wiedemann-Steiner Syndrome

Wiedemann-Steiner syndrome is a rare genetic disorder characterized by developmental delay, intellectual disability, and distinctive physical features such as hypertrichosis cubiti (excessive hair on the elbows). It is caused by mutations in the KMT2A gene and typically presents with a range of systemic symptoms involving growth, behavior, and skeletal development.

What causes Wiedemann-Steiner syndrome?

Wiedemann-Steiner syndrome is caused by a heterozygous mutation in the KMT2A gene, which provides instructions for making a protein that regulates gene expression during development. In the vast majority of cases, Wiedemann-Steiner syndrome occurs as a de novo mutation, meaning it is not inherited from parents but occurs spontaneously in the egg or sperm cell at conception.

How does Wiedemann-Steiner syndrome affect the body?

The clinical presentation of Wiedemann-Steiner syndrome is highly variable. While every individual is unique, the following features are frequently observed:

• Developmental and Cognitive: Mild to moderate intellectual disability and delayed speech acquisition.


• Physical Features: Characteristic facial features (such as long eyelashes and thick eyebrows) and hypertrichosis cubiti.


• Growth and Skeletal: Short stature and feeding difficulties during infancy, sometimes requiring nutritional support.


• Behavioral: Increased prevalence of autism spectrum traits or ADHD symptoms.

How common is Wiedemann-Steiner syndrome?

Wiedemann-Steiner syndrome is a very rare condition. While the exact prevalence is unknown due to underdiagnosis, it is estimated to affect fewer than 1 in 100,000 individuals globally. Our DiseaseMaps.org community currently supports 193 people with Wiedemann-Steiner syndrome, providing a vital network for families navigating this diagnosis.

How is it differentiated from other conditions?

Wiedemann-Steiner syndrome is often distinguished from other intellectual disability syndromes by the presence of specific skeletal anomalies and the hallmark "hairy elbows." Genetic testing, specifically exome sequencing, is the gold standard for confirming a diagnosis and differentiating it from conditions with overlapping symptoms like Cornelia de Lange syndrome.

Next steps

• Consult with a clinical geneticist to confirm the diagnosis via KMT2A sequencing.


• Schedule multidisciplinary assessments, including pediatric neurology, cardiology, and speech therapy.


• Connect with the DiseaseMaps.org community to share experiences with others living with Wiedemann-Steiner syndrome.


• Monitor for developmental milestones and address feeding or growth concerns early with a pediatric specialist.

Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Wiedemann-Steiner syndrome overview.


• Online Mendelian Inheritance in Man (OMIM): Entry #605130 (KMT2A).


• Orphanet: Rare disease database entry for Wiedemann-Steiner syndrome.


• Wiedemann-Steiner Syndrome Foundation: Patient-centered resources and clinical research updates.