Glycogen storage disorders (GSD) are a class of inborn metabolic abnormalities characterized by enzymatic defects in glycogen production or breakdown and are one of commonest metabolic disorders of the childhood. Their pathogenesis mostly involves the liver and muscles and can range in severity from minor disorders with a typical lifespan to those that are fatal in infancy. Different GSDs, such as type 0a, I, III (most common type), IV, VI, IX, and XI (based on specific gene variants) are now referred to as hepatic GSDs involving liver (+ muscle). GSDs show clinically in a wide range of ways, and they have typically been identified by combining clinical symptoms, biochemical data, and pathological findings. But due to lack of multicentre evaluation, there is persistent scarcity of data with regard to the overall spectrum of genetic defects in Indian children presenting with GSD, their natural course and genotype-phenotype correlation. Also, there is limited data on common genetic variations in Indian population causing hepatic glycogen storage diseases.

An Indian GSD registry is needed to describe the spectrum, natural course, genotype-phenotype correlation, outcome and response to medical therapy in Indian children with GSDs. The study would be the first to extensively describe the genotype of Indian children with GSD and their natural course. Being a multicentric study, the results generated would therefore be applicable to the whole of the country. Understanding the prevalent genotypes in Indian population and their related phenotype would help both the individual management decisions of these patients and further policy making for their diagnosis and treatment. Results from this study could thus guide appropriate decision making based on outcome and help choose the modality of treatment for the individual patient - medical, or liver transplantation.

• Primary objective:
• To describe the clinical presentation and outcome of genetically defined cases of pediatric hepatic glycogen storage diseases (GSD) patients.
• Study population: Genetically confirmed cases of hepatic GSDs will be enrolled from all the participating centres.
• Study design: Multicentric retrospective study (with concomitant long term prospective data collection)
• Study period: The study will be an ongoing effort with aim to continuosly expand the participation. Retrospective data collection (of previous data), analysis and drafting of manuscript would be completed between May 2024 to April 2025. New centers willing to join the consortium will be asked to submit their data as on the date of joining. Retrospective follow up data may be asked from the participating centres every every 6 months-1 year. Also, we would continue prospective data collection of newer GSD patients at the collaborating centres.

Inclusion Criteria:

• Children <18 years of age (at presentation) with genetically proven (homozygous or compound heterozygous mutations) hepatic glycogen storage diseases

  1. types 0a/GYS2 gene, I/G6PC or SLC37A4 gene variants, III/ AGL gene variants, IV/ GBE1 gene variants, VI/ PYGL gene variants, IX/ PHKA2, PHKB or PHKG2 gene variants and XI/ GLUT2/SLC2A2 gene variants.

     Exclusion Criteria:

     -

• Clinical, biochemical and histological evidence of GSDs without a confirmatory genetic sequencing report.

Genetically confirmed cases of hepatic GSDs will be enrolled from all the participating centres.