Irritability in young people with rare genetic conditions

This blog was originally shared on the Springer Nature Research Community: read it here

“I worry that they will get labelled as a naughty, difficult, or even an unlikeable child”. This was a sentiment I had heard before when conducting research interviews with parents of children with a rare genetic condition, often in relation to irritable behaviours that their children displayed.

I wondered if irritability is a widespread challenge for families of children with rare genetic conditions, and if so, what is the impact of this for children and young people? This led to the development of new research which aimed to understand irritability in children with rare genetic conditions, in particular copy number variants which are associated with neurodevelopmental disorders.

So, what is a copy number variant? DNA is an instruction manual containing all the information needed for creating and maintaining life. DNA is stored in chromosomes, which humans have 23 pairs of. A copy number variant, or a ‘CNV’ is a genetic change. CNVs can occur when a large section of a chromosome is either deleted or duplicated, meaning we can have either too little or too much DNA. Most people will have a CNV of some sort, but most are harmless. However, if the CNV occurs in a particular position on the chromosome, then it can impact our development or physical health. In fact, we know from research that there are a range of CNVs that impact child development, and we call these neurodevelopmental CNVs, or ‘ND-CNVs’.

Irritability is a common emotional state where a person feels easily annoyed or upset. We may be familiar with the idea of toddler tantrums, and whilst we wouldn’t want to treat everyday emotions as problematic, irritable behaviour that is unusual for a child’s age can be challenging for families. Clinically, a child may be considered irritable if they get angry more often and more quickly than their friends of the same age. Irritability is a common reason children are referred to child and adolescent mental health services, and it is a key feature of many neurodevelopmental and psychiatric conditions. Whilst there has been lots of work to understand irritability, there is very little for children with ND-CNVs.

This study aimed to understand whether children with ND-CNVs are more irritable than their peers. Senior author, Prof. Marianne van den Bree has developed one of the largest research cohorts of individuals with neurodevelopmental genetic conditions in the world. As part of these studies, we interviewed parents of 485 children with CNVs and 164 siblings with no known genetic condition. We asked them in detail about their child’s feelings and behaviours in an interview called the Child and Adolescent Psychiatric Assessment (CAPA). We also asked children to complete some tasks, including a test of intelligence, or IQ, called the Weschler Abbreviated Scale of Intelligence (WASI). We compared results from children who we knew had a ND-CNV, to a group of siblings who did not have a genetic condition. Our research discovered that children with ND-CNVs were almost 4 times more likely to be irritable, when compared to their siblings.

However, we had to ask ourselves some questions about why this might be. We already know that children with ND-CNVs are more likely to have a neurodevelopmental or psychiatric condition, such as attention deficit hyperactivity disorder, an anxiety disorder, a mood disorder, or autism, and that irritability is a common feature of these conditions. Therefore, it was important to consider whether this higher level of irritability identified in children with ND-CNVs was directly related to one of these conditions, regardless of whether they had a ND-CNV or not. However, this analysis revealed that higher levels of irritability in children with ND-CNVs were not simply because they are more likely to have other conditions that are associated with higher levels of irritability.

Following this, we found ourselves considering the links between learning ability and its impact on irritability. We know that children with ND-CNVs can experience difficulties with learning, and that young people who find it harder to learn may find it more difficult to complete tasks or communicate effectively. This can be frustrating, and lead to irritable behaviour. However, we found no strong evidence from the data that learning ability and irritability were associated. Additionally, we again found that children with a ND-CNV were more likely to be irritable than siblings who did have a similar learning ability.

Overall, we learned that children with ND-CNVs are more likely to be irritable, regardless of other preexisting mental health and neurodevelopmental conditions, or difficulty with learning. But what can we do with this information? Irritable behaviour is something that clinicians may not notice, and so we are advising doctors to be aware of the high risk of irritability in young people with rare genetic conditions in order to provide the most suitable treatment or intervention. For example, although learning ability doesn’t make children irritable, young people with genetic conditions who are irritable, may have difficulty with learning. So, if we want to intervene to help families manage or improve their child’s irritability, we may need to take learning ability into account. This could mean making modifications to interventions like cognitive behavioural therapy, so that treatments are more accessible for this group of young people. It may also be the case that parents and teachers would benefit from support with managing irritable behaviour at home, and in school.

It is also important to consider whether the irritability young people with a ND-CNV display could be an early marker of later mental health problems. Carrying out research with people multiple times, at multiple ages, will help us to figure out whether this might be the case. This would give us valuable information about whether early irritability interventions may help prevent later mental health problems. This is something we plan to investigate next. Irritability is an important part of the behavioural picture for lots of families with a child with a rare genetic condition, and it deserves further research attention.

We would like to thank all the children and families who took part in the study, as well as all the support we have had from charities, including Max Appeal and Unique.