COG5-CDG

COG5-CDG (also known as Congenital Disorder of Glycosylation type IIi) is an extremely rare autosomal recessive disorder caused by mutations in the COG5 gene, which encodes subunit 5 of the Conserved Oligomeric Golgi (COG) complex. The COG complex plays a critical role in the proper functioning of the Golgi apparatus, which is essential for the glycosylation of proteins and lipids. Defects in COG5 lead to abnormal protein glycosylation, resulting in a multisystem disorder. Clinical features of COG5-CDG typically present in infancy or early childhood and include psychomotor retardation, intellectual disability, hypotonia, and progressive microcephaly. Affected individuals may also exhibit speech and language delay, cerebellar hypoplasia, seizures, hepatic involvement (such as mildly elevated liver transaminases), and mild facial dysmorphism. Some patients have been reported with short stature, feeding difficulties, and recurrent infections. The neurological manifestations tend to be prominent, with variable severity among affected individuals. There is currently no specific or curative treatment for COG5-CDG. Management is supportive and symptomatic, focusing on physical therapy, occupational therapy, speech therapy, and seizure management when needed. Nutritional support may be required for patients with feeding difficulties. Diagnosis is typically established through isoelectric focusing of serum transferrin showing a type 2 pattern, followed by molecular genetic testing confirming biallelic pathogenic variants in COG5. Only a small number of patients have been described in the medical literature, making this one of the rarest subtypes of congenital disorders of glycosylation.

Common questions about COG5-CDG