Treatment and Improved Outcomes of Three Adult Patients With Guanidinoacetate Methyltransferase (GAMT) Deficiency
Abstract: Guanidinoacetate methyltransferase (GAMT) deficiency is a creatine synthesis disorder caused by biallelic pathogenic variants in GAMT. Early diagnosis and treatment can lead to normal neurocognitive outcomes, which has prompted its recent addition to the Recommended Uniform Screening Panel. Treatment typically includes creatine and ornithine supplementation, with or without arginine restriction or sodium benzoate. Here, we present the clinical outcomes of 3 adult patients with GAMT deficiency who began creatine and ornithine supplementation at varying ages. One patient started on treatment at 14 months of age and has had near-normal neurocognitive outcomes, highlighting the positive clinical impact of early treatment. Our findings also emphasize the need to continue treatment throughout adulthood, but further research is required to understand the natural history and determine the optimal treatment of GAMT deficiency in adults.
Parent Summary: This study reports on three adults with GAMT deficiency. Early diagnosis and treatment with creatine and ornithine supplements can lead to normal brain development, which is why GAMT deficiency was recently added to newborn screening tests. One patient who began treatment at 14 months old showed almost normal cognitive development, demonstrating the benefits of early intervention, while the patients diagnosed and treated later (at age 12 and 19) continue to need assistance with activities of daily living. The study also highlights the importance of continuing treatment into adulthood, but more research is needed to understand the long-term effects and find the best treatment plan for adults with this condition.
Link to article: https://onlinelibrary.wiley.com/doi/10.1002/jmd2.70019
PubMed: https://pubmed.ncbi.nlm.nih.gov/40330029/
Authors: Angela Lee, Judith Weisenberg, Elizabeth Toolan, Marwan Shinawi
Key Terms: GAMT, Clinical Study, Adult Patient