Pharmacogenetically-guided Escitalopram Treatment for Pediatric Anxiety: Aiming to Improve Safety and Efficacy (PrEcISE)

Inclusion Criteria: 1. Written, informed assent and consent. 2. Patients, parent/guardian must be fluent in the English. 3. 12 to 17 years of age, inclusive, at Visit 1. 4. Patients must meet DSM-512 criteria for generalized, social and/or separation anxiety disorder, confirmed by the MINI-KID. 5. PARS score ≥15 at Visit 1 and Visit 2. 6. No initiation of psychotherapy within 8 weeks of screening (Visit 1). Current therapy much be stable for ≥2 months prior to baseline (Visit 2). 7. Clinical Global Impressions-Severity (CGI-S) score ≥4 at Visits 1 \& 2. 8. Caregiver who is willing to consent to be responsible for safety monitoring of the patient, provide information about the patient's condition, oversee the administration of the investigational product. 9. No clinically significant abnormalities on physical examination and EKG. 10. Negative pregnancy test at Visit 1 in females. 11. Negative urine drug screen at Visit 1. 12. Sexually active patients must practice a reliable method of contraception that will continue for the duration of the study and for a minimum of 30 days following the end of study participation. Reliable methods of contraception are defined below; other forms of contraceptives (pharmacological and/or non-pharmacological) are not accepted: 1. Surgical sterilization 2. Oral contraceptives (e.g. estrogen-progestin combination or progestin) 3. Transdermally-delivered contraceptives (e.g., Ortho-Evra), depot injections (e.g., Depo-Provera) 4. Vaginal contraceptive ring (e.g., NuvaRing), contraceptive implants (e.g., Implanon, Norplant II/Jadelle) 5. An intrauterine device 6. Diaphragm plus condom. - Exclusion Criteria: 1. Co-occurring DSM-5 mood disorder (except persistent depressive disorder, unspecified depressive disorder, provided that the primary diagnosis is an anxiety disorder), eating, bipolar or psychotic disorders. 2. A lifetime diagnosis of an intellectual disability. 3. A significant history of trauma exposure. 4. A history of SSRI treatment within 12 weeks of baseline or current treatment with a medication with psychiatric effects that requires \>5 half-lives for washout History of non-response to \>2 SSRIs. 5. Allergy, intolerance, non-response or hypersensitivity to escitalopram. Major neurological or medical illness or head trauma with ≥5 minutes loss of consciousness. 6. Alcohol or substance use disorder within the past 6 months (nicotine use is permitted). 7. Psychotherapy initiated within 8 weeks of screening (Visit 1), or plans to initiate/change therapy during the study. 8. Pregnant, breastfeeding, lactating, and/or planning to become pregnant during the study or within 30 days following the end of study participation. 9. Positive urine pregnancy test. 10. A positive urine drug screen. 11. Patient lives \>90 minutes from UC or unable to attend follow-up visits. Suicide risk as determined by either: (1) any suicide attempt within the past 6 months and/or (2) significant risk at Visit 1 (Screening) or Visit 2 (Baseline), as judged by the Investigator. 12. QTc \>450 in males or \>460 in females (prolonged QTc based on American Heart Association recommendations for Standardization and Interpretation of the EKG 13. Patients who are unable to swallow capsules.