New research by the Murdoch Children’s Research Institute (MCRI) and Netherland’s Radboud University Medical Centre has provided the first ever in-depth examination of speech and language abilities in children with Koolen-de Vries syndrome (KdVS).

KdVs is a disorder characterised by developmental delay and mild to moderate intellectual disability.

Children with this disorder typically have a disposition that is described as cheerful, sociable, and cooperative. They usually have weak muscle tone (hypotonia) in childhood and about half have recurrent seizures (epilepsy).

KdVS is a multi-system disorder caused by disruption of the KANSL1 gene. The disorder has a prevalence of 1 in 16,000 worldwide and it is estimated to affect about 300 Australian children.

A greater understanding of the speech, language and reading deficits of KdVS may help to unravel the relevance of KANSL1 gene to child speech and language development.

MCRI’s research co-author, Professor Angela Morgan, said that these findings that were published in The European Journal of Human Genetics will also help families and clinicians with prognostic counselling and the application of more targeted speech therapies for social, literacy and academic outcomes for children with KdVS.

The team assessed individuals with KdVS aged from one to 27 years for oral-motor, speech, language, literacy and social functioning.

Speech was characterised by:

• Apraxia - a motor speech disorder. Children have problems saying sounds, syllables, and words (100%)
• Dysarthria - a condition in which the muscles you use for speech are weak or you have difficulty controlling them (93%)
• Stuttering (17%)

In infancy they found that children had exceptionally low-tone and a high prevalence of gastrooesophageal reflux, which was associated with feeding difficulties.

Professor Morgan said that speech and language development was delayed on average to around two-and-a-half to three-and-a-half years of age.

“These children are highly sociable with a strong desire to communicate. As a result they keep practising speech even though it is really challenging for them to overcome the severe oral weakness in life that prohibits early speech development. They also tend to find powerful methods of communicating beyond spoken language (such as using electronic devices) because for some kids they can be as old as seven before they start to speak.”

The study identified the need for greater understanding and expression of language, particularly in relation to their peers.

“Our study also highlighted the critical need for speech therapy and non-verbal communication (e.g., sign language) to support kids with KdVS particularly while they are in preschool,” Professor Morgan said.

Professor David Amor, a clinical geneticist at MCRI and co-author of the study, said that although KdVS cannot be cured, these new insights into speech and language problems in children with KdVS will lead to better treatments that will improve communication and enhance the quality of life of the children and their families.