Nonketotic Hyperglycinemia in Central and Appalachian Kentucky

Nonketotic hyperglycinemia (NKH) is a rare genetic disorder with a global incidence of 0.4 to 1.3 per 100 000 live births with regional variation. We sought to estimate the regional birth incidence and describe the clinical and genetic features of NKH in central and Appalachian Kentucky. Fifteen patients met standard diagnostic criteria for NKH; 13 were born in Kentucky, yielding an estimated birth incidence of 2.53 per 100 000 live births (13/513 419; 95% CI 1.35-4.33). Of those with available genetic data (n = 9), 8 carried <i>GLDC</i> variants, with 6 having the c.1166C>T (p.A389V) variant. We found a higher incidence of NKH in central and Appalachian Kentucky compared to global estimates, with local enrichment of the p.A389V variant. These findings highlight the need for clinician awareness and further research to inform regional screening and management.