A study has found that children with rare genetic disorders have an increased risk of developmental, behavioural, and mental health problems.
University of Cambridge researchers recommend children with intellectual disabilities or developmental delays partake in rapid whole genome sequencing to identify any underlying rare genetic disorders.
Rare genetic disorders often affect fewer than one in 2,000 of the general population. There are over 6,000 known rare disorders with minimal effective treatment available. Statistics indicate that eight out of 10 rare disorders have a genetic cause, and 99% of genetic conditions classify as rare.
The research is published in The Lancet Psychiatry, concluding the results of an analysis of around 2,800 young people with rare genetic diseases and intellectual disabilities.
How do rare genetic disorders affect children’s behaviour?
Researchers from the University of Cambridge, University College London, and Cardiff University developed IMAGINE ID, a national UK cohort study discovering how genetic changes impact children and young people’s behaviour.
The participants were between four and 19 years old, with 74% having an intellectual disability caused by duplication or deletion of sections of DNA – known as a copy number variant (CNV). The 26% of other participants had a disability caused by a single error in their DNA – a change in the A, C, G or T nucleotides – referred to as a single nucleotide variant (SNV).
Compared to the English national population, the children in the study with rare genetic disorders were almost 30 times as likely to be diagnosed as autistic. In the general population, 1.2% of people were diagnosed with autism compared to 36% of the study participants. Additionally, ADHD was prominent in 22% of the study population compared to 1.6% of the general population, meaning that children with rare genetic disorders were more than 13 times more likely to have the condition.
Furthermore, one in eight children (12%) were diagnosed with oppositional defiant disorder, a condition causing hostility and defiance towards others. This was 4.4 times higher than the general population.
High rates of mental health problems in children with rare genetic disorders were found in the study. One in ten (11%) had an anxiety disorder – a 1.5 times increased risk. However, the researchers saw lower rates of depression at just 0.4% compared to 2.1% of the general population, but this figure may increase in the future. The study found that 94% of the children reported at least one significant physical health problem, including disturbed sleep, motor or movement disorders or seizures.
Dr Jeanne Wolstencroft from Great Ormond Street Institute of Child Health, University College London, said: “Routine genomic testing now allows parents to understand the genetic cause of intellectual disabilities in an increasing number of children, but because so many of these conditions are rare, we still lack information on the impact this has on their children’s future mental health.
“We already know that intellectual disabilities tend to be associated with an increased likelihood of neurodevelopmental conditions, as well as emotional and behavioural difficulties, but we found that where there is an identifiable genetic cause, the likelihood is amplified considerably. This suggests that these children should be provided with early assessment and help where appropriate.”
Social and education disadvantages
The team highlighted for the first time that children with intellectual disability caused by a rare genetic disorder from a family member are more likely to come from a deprived socioeconomic background. This implies that some parents or family members with the same condition may have unknown mental, behavioural and developmental difficulties placing them at a social and educational disadvantage. These children were more likely to live with a neuropsychiatric condition and to present behavioural problems.
Professor David Skuse from Great Ormond Street Institute of Child Health, University College London, said: “We hope this work helps improve the targeting of assessments and interventions to support families at the earliest opportunity. We’d like to see better training for health care providers about the wider use and utility of genetic testing. We have identified its potential value in terms of prioritising children with mental health needs for child mental health services, who are currently hugely limited in the UK.”
