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Chapter 8210chapter 6, has also been reported in individuals from the general population but only after the age of 65 years.43 These examples may suggest that some of the mechanisms contributing to age-related disorders are similar between adults with 22q11.2DS and the general population, but have their onset earlier in life. These findings may also suggest the presence of other neurodegenerative conditions in GNDs at an earlier age than would be expected based on results from the general population. In future research it would be interesting to study other neurodegenerative conditions in GNDs, such as cognitive decline/dementia.With respect to 22q11.2DS, hemizygosity of protein-coding genes within the 22q11.2 deletion region that were suggested to contribute to conditions at adult age included TBX1 and genes involved in mitochondrial function.54TBX1 is important for the 22q11.2DS somatic phenotype, and is involved in the development of the cardiac and vascular system, including the stria vascularis, central nervous system and inner ear, including the semicircular canal. 55, 56 Described in chapter 4, hemizygosity of TBX1 may result in vulnerability of the cochlea and contribute to age-related hearing loss. In addition, TBX1 may be responsible for retinovascular abnormalities found in individuals with 22q11.2DS because of its involvement in angiogenesis and vessel branching described in chapter 6.57 Other candidate genes include those involved in mitochondrial function; at least six are located in the 22q11.2 region.54 Mitochondrial dysfunction and oxidative stress have been proposed, in chapters 3, 4 and 6, as possible contributors to degenerative changes which may contribute to the development of age-related hearing loss, retinal abnormalities, Parkinson’s disease as well as other conditions outside the scope of this thesis but important for the adult phenotype, such as schizophrenia. 58-61Methodological considerationsResults described in this thesis should be considered in the context of several strengths and limitations. Some related to more than one study and will be discussed in the following paragraphs because they may be of relevance to future studies. Strengths included the relatively large samples of adults with 22q11.2DS. In addition, adults were often examined as part of routine 22q11.2DS-related care.62 For example, ophthalmic, neurologic