People with mosaicism for trisomy 21 have been shown to exhibit the many of same phenotypic traits present in people with non-mosaic Down syndrome, but with varying symptom severity. However, the behavioral phenotype of people with mosaic Down syndrome (mDS) has not been well characterized. This study aimed to examine the prevalence of self-report and caregiver-report symptoms of depression and anxiety among a sample of 62 participants with mDS aged 12 - 46, and assess their association with the percentage of trisomy 21 in blood and/or buccal mucosa cells. The results showed that 53% of the participants reported clinically significant depression symptoms and 76% reported clinically significant anxiety symptoms. No clear associations were observed between the percentage of trisomic cells and total anxiety or depression, but a significant positive association between the proband-reported specific fears subscale and the percentage of trisomic cells in buccal specimens was detected (r = .43, p = .007). This study highlights the high occurrence of depression and anxiety symptoms in individuals with mDS and the need for routine assessment to optimize their care. It also demonstrates the ability of people with mDS to complete these evaluations, thereby supporting their inclusion in research studies/clinical trials.

Drs. Brown and Jackson-Cook serve as unpaid scientific advisors for the International Mosaic Down Syndrome Association. The authors have no other conflicts of interest to disclose.

This study was funded by NIH grants K08HD092610 and UL1TR002649.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Institutional Review Board (IRB) of Virginia Commonwealth University gave ethical approval for this work.

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Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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All data produced in the present study are available upon reasonable request to the authors.