Prospective Collection of Biospecimen in Pediatric Patients and Adult Guardians Diagnosed With Glycogen Storage Disease Type 1B (GSD1b)

Inclusion Criteria: * Subjects ages 4-85 * Subjects that are diagnosed with Glycogen Storage Disease Type Ib (GSD1b, von Gierke disease) * Subjects who are G339C Homozygous or L348FS Homozygous or G339C/ L348FS heterozygous or are the biological parent of subjects diagnosed with Glycogen Storage Disease Type Ib (GSD1b, von Gierke disease) and are a biological parent of a subject in Cohort 1 (G339C homozygous) or Cohort 2 (L348FS homozygous) * Subjects or guardians must be willing and able to provide appropriate photo identification to mobile phlebotomist during at-home visit for verification of identity * Subjects and/or Guardians must be willing and able to provide appropriate written informed consent and/or assent, as applicable Exclusion Criteria: * Subjects will be excluded if they experienced excess blood loss, including blood donation defined as 250 mL in the last month or 500 mL in the last two months. For subjects in the pediatric population, subjects will be excluded if they experienced excess blood loss, including blood donation defined as 3 mL/kg or up to 50 mL in the last 8-weeks. * For requests that do not include pregnant subjects, subjects will be excluded if they are pregnant or nursing. * For requests that do not include subjects with infectious diseases, subjects will be excluded if they have current, active HIV, hepatitis or other infectious diseases (self-reported or medical history reviewed). * Subjects will be excluded if they have taken an investigational product in the last 30 days.