Genetic testing of adults with intellectual disability

Abstract

MethodPatients known to learning disability services in two health boards in southeast Scotland were cross-matched with the patients tested at the Western General Hospital in Edinburgh. Those with a positive genetic diagnosis were identified. Semi-structured interviews were conducted with senior learning disability psychiatrists and clinical genetics consultants.ResultsOf the 3323 patients with intellectual disability across both health boards, 41% have had genetic tests and 6% have an identified genetic abnormality as the cause for their intellectual disability. Of the 1349 patients who have been tested, a genetic abnormality was found in 14%. Psychiatrists named several benefits to genetic testing, but they also highlighted a number of non-medical reasons for not testing adults with intellectual disability.Clinical implicationsIdentifying genetic aetiology in intellectual disability has a number of benefits. Our study would indicate that genetic diagnoses are being missed due to a lack of genetic testing in this patient group. Adult learning disability services need to consider increasing genetic testing.

Designing genetic studies for people with intellectual disabilities: Practical lessons from a pilot study

“…The challenges to recruitment of PwID to genetic studies relating to informed consent are well documented in literature (Adlington et al, 2019; De Villiers & Porteous, 2012). The International Association for the Scientific Study of Intellectual Disabilities advice in the absence of family members, collective professional decision‐making is the most effective way to safeguard the potential research participant's best interests (Dalton & McVilly, 2006).…”

“…This can present a barrier as clinicians could struggle to identify potential benefits to communicate to patients and carers to enable recruitment. There is need for clinician training in this matter (Adlington et al, 2019; De Villiers & Porteous, 2012). Research evidence following genetic testing and its feedback on participant quality of life outcomes is sparse and if improved, may influence referral rates from healthcare teams (Adlington et al, 2019).…”

“…For PwID likely to experience extreme distress undergoing venepuncture, current practice is of taking samples during sedation for medically indicated procedures (dental check/scans etc.) (De Villiers & Porteous, 2012). This pathway was identified for enabling bloods in 15 PwID whose families had assented.…”

“…PwID are more likely to have mental and physical health co‐morbidity and premature mortality (Heslop et al, 2013; Shankar et al, 2020). Approximately 20% of PwID have recognised genetic impairments which predispose to physical, psychological and neurodevelopmental co‐morbidities (De Villiers & Porteous, 2012; Palmer et al, 2014). Specific genetic disorders are associated with seizures, self‐injurious behaviours and affective/psychotic illnesses (Kidd et al, 2014; Soni et al, 2008).…”

“…It can also be the pre‐cursor for delivering personalised and precision treatments using vehicles such as pharmacogenomics (Perera et al, 2022). However genetic investigation is not routine practice for PwID and comorbid disorders in the United Kingdom (De Villiers & Porteous, 2012).…”