Treatment of Atopic Dermatitis and Alopecia Areata With Abrocitinib in Individuals With Down Syndrome

Inclusion Criteria: Participants must meet all of the following criteria to be eligible as study participants: * Male or female participants who are at least 12 years old, for whom signed informed consent can be provided by parent or legal guardian/LAR prior to participation in any study assessments or procedures. * Diagnosis of Trisomy 21 or translocation Down Syndrome. * Participant is able to adhere to the study visit schedule and other protocol requirements. * Females of childbearing potential (FCBP) must have a negative pregnancy test at Screening and Week 0/Baseline. While on investigational product and for at least 28 days after taking the last dose of investigational product (IP), FCBP who engage in activity in which conception is possible must use one of the approved contraceptive options described below: a. Any one of the following highly effective methods: hormonal contraception (oral, injection, implant, transdermal patch, vaginal ring); intrauterine device (IUD); tubal ligation; or partner's vasectomy; or b. Male or female condom (latex condom or non-latex condom NOT made out of natural \[animal\] membrane \[for example, polyurethane\]). * Participant has a history of ≥6 months AD (≥7%BSA) or AA (≥25% scalp involvement). If the participant presents with both conditions, but only one meets the inclusion criteria, then the participant can only be enrolled under that category. If a participant meets inclusion criteria for both conditions at the Baseline visit, the…