Down syndrome and autoimmune eye disease

TO THE EDITOR:

We read with great interest the recent publication on characterising autoimmune eye disease in Down syndrome (DS) [1]. People with DS are disproportionately affected with autoimmune diseases including, but not limited to, thyroid dysfunction, coeliac disease, and inflammatory arthritis [1]. While several ocular manifestations have been studied in DS, studies characterising uveitis in this population are limited.

In our recent study on keratoconus in DS [2], we observed only one case of uveitis in 190 individuals with DS. This translates to a prevalence of 0.53% (95% CI 0.07–3.72%). However, this is still 10x the prevalence of uveitis reported within the general population [3]. Among our cohort of participants with DS, self-reported autoimmune related conditions are outlined in Table 1. In this series, hypothyroid, coeliac disease and psoriasis were the most commonly reported autoimmune related diseases. Eight participants with DS were affected by ≥2 conditions outlined in Table 1. Interestingly, the proportion of DS affected by these conditions was greater than the previously reported proportions in the general population, i.e., 3.0% hypothyroid, 1.9% coeliac disease and 1.5% psoriasis in the general population [4].

Table 1.

Self-reported autoimmune disease in Down syndrome (DS), N (participants) = 190.

Autoimmune disease	n (%) of DS participants affected
Alopecia (unclassified)	4 (2.11%)
Coeliac disease	13 (6.84%)
Juvenile idiopathic arthritis	1 (0.53%)
Psoriasis	6 (3.16%)
Psoriatic arthritis	1 (0.53%)
Thyroid dysfunction	24 (12.63%)
‐ Hypothyroid ‐ Hyperthyroid ‐ Unclassified	18 (9.47%) 2 (1.05%) 4 (2.11%)
Type 1 diabetes	4 (2.11%)

The life expectancy of individuals with Down syndrome has increased, therefore, we may observe an increase in the rates of observed autoimmune disease, with highest prevalence often around age 20–40 years in the general population. Additionally, the prevalence of autoimmune disease is expected to increase globally [5]. This has been suggested to be due to environmental factors including changes to food, stress, and climate change [5]. It is conceivable that these environmental changes may exacerbate the manifestation of autoimmune disease in DS and increase the risk for inflammatory eye disease.

Zaki et al. [1] highlighted that uveitis presented in a similar fashion among DS individuals in their series, based on bilaterality, chronicity, anterior and intermediate segment involvement, and diagnoses of idiopathic uveitis. Unfortunately, for a number of reasons, uveitis in DS may be under-reported and more common than generally accepted. The detection of anti-retinal autoantibodies in all three consecutively tested DS individuals by Zaki et al. [1] suggests the relationship between DS and autoimmune eye disease is an important topic for further study.

Author contributions

All authors contributed equally to this work.

Funding

Joyce Mathan’s PhD was funded by: Auckland Medical Research Foundation Doctoral Scholarship, Save Sight Society Grant, Heather Mackintosh Research Scholarship, and New Zealand Association of Optometrists Postgraduate Scholarship. The funding organisations had no role in the design or conduct of the research.

Data availability

All data generated or analysed during this study are included in this published article.

Competing interests

The authors declare no competing interests.

Ethics

Health and Disability Ethics Committees (18/NTA/192). The tenets of the Declaration of Helsinki were adhered to.