A Study to Assess the Efficacy and Safety of Weekly Doses of GLM101 in Participants With PMM2-CDG

Inclusion criteria: Participant is eligible for participation in the study if all of the following apply: * Participant is aged ≥ 4 years old at the time of signing the consent. * Participant with molecular diagnosis of PMM2-CDG. Diagnosis is defined as biallelic pathogenic and/or likely pathogenic variants, or, in the case of variants of uncertain pathogenicity, demonstration of biallelic variants and PMM2 enzyme activity consistent with a diagnosis of PMM2-CDG. Diagnosis with laboratory report(s) on file is required. * Participant is willing and capable of completing the ICARS in its entirety without any assessment deemed as "not evaluable". * Participant screening total ICARS score is ≥ 20 and ≤ 80 . * Male or female participant has appropriate measures in place to prevent pregnancy: * If the participant is a woman of childbearing potential, i.e., fertile, following menarche and until becoming postmenopausal unless permanently sterile (permanent sterilization methods include hysterectomy, bilateral salpingectomy, and bilateral oophorectomy), she must not be pregnant (confirmed by a negative serum pregnancy test), is using a medically accepted method of contraception (abstinence, a hormonal contraceptive associated with inhibition of ovulation in conjunction with a barrier method, or use of an intrauterine device), and must agree to continue using this method for 50 days after the last infusion. Note: sexual abstinence is considered a highly effective method only if def…