A Study of GlcNAc on Tear Production in 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…