Page 206 - Characterization of genetic neurodevelopmental disorders at adult age, with a focus on 22q11.2 deletion syndrome - Emma Boersma

Chapter 8
intellectual disability.10 Prevalence rates that seem to be higher compared to
the general population and to adults with an intellectual disability, included
for example Parkinson’s disease, astigmatism, posterior embryotoxon and
retinal vascular tortuosity,2, 3, 11-13 although not all of these conditions have
been studied well in other GNDs. In the following paragraphs, the most
important results and recommendations for clinical practice and future
studies in adults with 22q11.2DS are discussed per study topic.
Parkinson’s disease
In chapter 3, it was found that adults with 22q11.2DS have an increased risk
of Parkinson’s disease; much higher compared to what has been reported
in the general population.2 This suggests that hemizygosity of one or more
genes within the typically deleted 22q11.2 region convey an increased
risk of Parkinson’s disease. Future study of these genes and underlying
mechanisms may provide insights into the pathophysiology of Parkinson’s
disease in 22q11.2DS, that may possibly also be of importance for the
study of idiopathic Parkinson’s disease. Other main findings included a
sharp increase in Parkinson’s disease after the age of 50 years, with motor
onset about one decade earlier, and the equal prevalence of Parkinson’s
disease between males and females with 22q11.2DS, different from what
has been reported in the general population and previous studies of adults
with 22q11.2DS.2, 14 These insights do not only provide directions for future
research but are also of clinical relevance. Based on these findings and
the impact of Parkinson’s disease on a person’s life, standard neurological
assessments seem warranted after the age of 40 years to screen for
parkinsonian (motor) features. Early detection of Parkinson’s disease can
be beneficial,15 since it allows for early treatment with anti-parkinsonian
medication which was found to be able to reduce motor symptoms in the
majority of individuals with 22q11.2DS.14
Hearing loss and otolaryngological findings
In chapter 4, it was found that the majority of adults with 22q11.2DS had
hearing loss, mostly of the higher frequencies, while only ~30% of adults
were known to have hearing loss prior to the routine audiometric screening.
Hearing loss started at a much younger age compared to the general
population, though with a pattern suggestive of age-related hearing loss
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