Wiedemann-Steiner Syndrome or WSS is a rare genetic disease caused due to mutation in the KMT2A gene (MLL1) on chromosome 11’s long arm.

Wiedemann-Steiner Syndrome was described clinically by Hans-Rudolf Wiedemann in 1989 and genetically identified in 2012 by researchers in England led by Dr. Wendy D. Jones.

The KMT2A gene helps in modifying expression in other genes. WSS is an autosomal dominant, which means that for a person to have a WSS, only one abnormal gene copy is needed.

In a majority of WSS cases, the mutation happened de novo (neither parent had it, nor it was sporadic). Offsprings of people affected with WSS have around 50% chance of contracting the disease.

Symptoms of WSS

WSS patients generally suffer from several physical symptoms and handicaps and tend to struggle with cognitive deficits right from childhood. Some of the symptoms of Wiedemann–Steiner syndrome include:
  • Short stature
  • Characteristic facial features
  • Developmental delay
  • Hypotonia (low muscle tone), especially in infancy
  • Hypertrichosis cubiti (hairy elbows)
  • Sleeping difficulties
  • Dental issues
  • Feeding and digestion complexities

Causes and Diagnosis of WSS

As described above, Wiedemann–Steiner Syndrome happens due to a mutation in the KMT2A (MLL1) gene. However, the exact mechanism by which the KMT2A gene mutation causes the Wiedemann–Steiner syndrome phenotype is not yet known.

Frequently, patients with WSS are incorrectly diagnosed. Patients suffering from WSS are often diagnosed with autism, Rubinstein–Taybi syndrome, or even Kabuki syndrome.

While standard screening tests done during pregnancy can detect diseases like Down Syndrome, there is limited diagnostic testing for Wiedemann–Steiner syndrome.

If WSS is suspected, the MLL1 gene can be analyzed. Alternatively, WSS may be diagnosed by whole gene sequencing or whole-exome sequencing.

Additionally, baseline genetic screening tests usually conducted after birth doesn’t include WSS testing. A majority of the time, healthcare professionals do not suggest whole exome testing as it’s costly and these are not covered by insurance.


Scientists have not been able to design a specific treatment for people suffering from Wiedemann–Steiner syndrome.

Children suffering from WSS are known to benefit from various supportive therapies like speech therapy, physiotherapy, behavioral therapy, special educational support, and supplemental nutrition to deal with poor feeding.

Music therapy and hippotherapy are also known to benefit patients affected by WSS. School-aged children having WSS can benefit from modified instruction, one-on-one support, modified instruction, and special day-class environments.

Life Expectancy

Lack of data has restricted researchers from coming out with clear statistics showing patients with WSS have got lesser life expectancy than an average human being.

They are positively affected by the comorbid conditions, but to state that they have a lower life expectancy than you and I would be bordering hypothesis.