Page 14 - Let them speak Towards a patient reported outcome measure set for

Chapter 1
(Genetic) intellectual disabilities: patients’ needs
According to the European Parlement and the Council of the European
Union, diseases are classified as ‘rare’ if they affect fewer than five in 10.000
individuals (1). Collectively, rare diseases are estimated to affect approximately
3-6% of the population, with nearly 80% having an identified genetic cause (2).
These rare genetic diseases can be associated with intellectual disabilities
(ID), which are characterized by impairments in intellectual and adaptive
functioning with onset before 18 years of age (3). ID affects 1-3% of the
population (4), and advances in diagnostic techniques now allow a genetic
cause to be identified in almost half of the affected individuals (5, 6).
ID with and without a known genetic cause, henceforth called (genetic) ID
(GID), can significantly affect daily functioning and well-being of individuals
due to the complex and broad spectrum of physical and neuropsychiatric
manifestations (7). Physical manifestations may include motor impairments
and heart defects, while neuropsychiatric features may encompass
autism and challenging behavior (8). The manifestations can be extremely
variable within and between disorders. For instance, within the Tuberous
Sclerosis Complex (TSC) population, a broad spectrum of intellectual
levels is observed, ranging from severe ID to an above average intellectual
functioning (9). In addition, distinct manifestations between disorders are
also common, such as obesity in Prader-Willi syndrome and parkinsonian
features in 22q11 deletion syndrome (10-12). Affected individuals often
require lifelong care and support, which places a substantial burden on the
individual, their caregivers, and the healthcare system (13, 14). Moreover,
these complex and diverse manifestations pose significant challenges
to delivering appropriate care and conducting high-quality research,
contributing to health disparities in this already vulnerable population (15,
16). Despite the complexity and heterogeneity of GID, its impact on daily
life experienced by affected individuals can overlap across conditions.
Individuals often face mental health problems, difficulties with physical
activities, and participation restrictions (17, 18). Understanding this impact
of GID from those affected is essential. This understanding enables us to
organize suitable, high-quality care and to conduct research that is relevant
to individuals with GID.
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