A Study of GlcNAc on Tear Production in NGLY1-CDDG

In patients with NGLY1-CDDG, the disorder can lead to eye damage due to not being able to produce enough tears. This study is being done to see if the dietary supplement, GlcNAc, improves tear production in patients with NGLY1-CDDG.

Inclusion Criteria: * Previously molecularly confirmed NGLY1-CDDG * Between the ages of 1 year old to 60 years old * Parent or legal guardian available to provide consent on behalf of minor subjects or adult subjects who are unable to give informed consent due to developmental disabilities. Willingness of subject or legal guardian to provide consent. * Non-pregnant, non-lactating female subjects of childbearing potential who are heterosexually active must agree to use a highly effective method of contraception for the duration of the study. A highly effective method of birth control is defined as one that results in a low failure rate (i.e., \<1% per year) when used consistently and correctly, such as oral/injectable/inserted/implanted/transdermal contraceptives, condom with diaphragm, condom with spermicide, diaphragm with spermicide, intrauterine hormone- releasing system, or intrauterine device (IUD), or sexual abstinence. Contraception is not required where at least 6 weeks have passed since sterilization, defined as females having undergone one of the following surgeries: hysterectomy, bilateral tubal ligation or occlusion, bilateral oophorectomy, or bilateral salpingectomy; and males who are vasectomized. Contraception is not required where females are postmenopausal (defined as 12 consecutive months of spontaneous amenorrhea and age ≥51 years).. Exclusion Criteria * Hypersensitivity to any of the components of the placebo * History of treatment with GlcNAc within 28 days of Visit 1 * Participation in another therapeutic trial - the subject will not be permitted to participate in any other drug trial during the blinded phase and during the 28 days prior to Visit 1 * Shellfish allergy * Planned eye surgery within 3 months of enrollment * • Females that are pregnant, nursing or less than 6 months postpartum or attempting to conceive