AE. Bozacı, İ. Erdal, G. Öner, ÖA. Clark, ÖY. Köken and E. Soyuçen (2026). Clinical and laboratory outcomes of ketogenic versus glycine-restricted diet in nonketotic hyperglycinemia: A comparative study. Molecular genetics and metabolism, 148(2), 110118. https://doi.org/10.1016/j.ymgme.2026.110118

PubMed 41966573

[Abstract]
AIM: This study aimed to compare the clinical, biochemical, and nutritional outcomes of classical nonketotic hyperglycinemia (NKH) patients treated with a ketogenic diet (KD) versus a glycine-restricted diet (GRD).

METHODS: This retrospective study included patients with classical nonketotic hyperglycinemia treated with either a KD (n = 8) or a GRD (n = 6). Seizure frequency, seizure scores, antiepileptic drug (AED) use, motor function (GMFCS-E&R), swallowing difficulties, plasma glycine levels, and nutritional parameters were evaluated before and after dietary treatment.

RESULTS: Baseline characteristics did not differ significantly between groups. Post-treatment assessments showed no significant differences in GMFCS scores, swallowing function, or plasma glycine levels. However, KD resulted in significantly reduced seizure frequency and seizure scores, and decreased AED use compared with GRD. Within-group analysis showed significant seizure control in the KD group, whereas seizure frequency increased in the GRD group. An increase in LDL cholesterol was observed in KD group, as expected; other nutritional parameters remained stable. Mortality was similarly high in both groups.

CONCLUSION: Neither diet altered biochemical parameters or motor outcomes. However, KD provided better seizure control compared to GRD, supporting its role as a useful adjunctive therapy in NKH.