Early Diagnosis and Targeted Therapy in SLC39A8-Congenital Disorder of Glycosylation: A Case Report From Bulgaria

SLC39A8-congenital disorder of glycosylation (SLC39A8-CDG) is a rare autosomal recessive metabolic disease of manganese transport, leading to defective glycosylation and mitochondrial dysfunction. An eight-month-old male infant with severe hypotonia, developmental delay, and dystonic episodes was initially misdiagnosed as epilepsy. Genetic testing identified a homozygous pathogenic variant in the SLC39A8 gene, and biochemical analysis confirmed low manganese levels. Upon initiation of oral manganese sulfate therapy, the patient demonstrated significant clinical improvement, including the achievement of new motor milestones. To our knowledge, this is the first documented case in Bulgaria. This case underscores the importance of early genetic diagnosis and targeted metabolic treatment in altering the clinical trajectory of SLC39A8-CDG. Timely recognition allows for intervention in a disorder that, despite its rarity, has a modifiable course and potential for meaningful developmental gains.