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COG5 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

COG5 gene

The COG5 gene provides instructions for making a protein essential for the proper transport and modification of proteins within the Golgi apparatus.

Overview

The COG5 gene provides instructions for making a protein called component of oligomeric Golgi complex 5 (COG5). This protein is a subunit of the conserved oligomeric Golgi (COG) complex, a group of proteins located in the Golgi apparatus—a cell structure responsible for modifying newly produced proteins and fats.

Normal Function

The COG complex is vital for the transport of proteins, including enzymes required for glycosylation, a process where sugar molecules (oligosaccharides) are attached to proteins and fats to enable them to perform a wider variety of functions. The complex specifically facilitates retrograde transport, which moves proteins backward through the Golgi apparatus to recycle them and ensure they are correctly positioned for proper glycosylation.

Proteins are moved within the Golgi in sac-like structures called vesicles. The COG complex controls the tethering (attachment) of these vesicles to the Golgi membrane, allowing them to release their contents into the structure.

Health Conditions Related to Genetic Changes

COG5-congenital disorder of glycosylation

Mutations in the COG5 gene can cause COG5-congenital disorder of glycosylation (COG5-CDG). This condition often leads to intellectual disability, developmental delay, and other abnormalities.

  • Mechanism: Mutations reduce or eliminate the COG5 protein, disrupting retrograde transport in the Golgi apparatus.
  • Impact: This disruption results in abnormal protein glycosylation, which can affect multiple body systems.
  • Severity: The severity of the condition is directly related to the amount of functional COG5 protein remaining in the cells.

Other Names for This Gene

  • 13S golgi transport complex 1 90 kDa subunit
  • CDG2I
  • COG complex subunit 5
  • conserved oligomeric Golgi complex protein 5
  • conserved oligomeric Golgi complex subunit 5
  • GOLTC1
  • GTC90

Frequently Asked Questions

Key early clues include profound developmental delay, hypotonia, seizures, failure to thrive, and dysmorphic facial features. Additional red flags are liver dysfunction, coagulation abnormalities, or unexplained sensorineural hearing loss, which together suggest a disorder of protein glycosylation.
Diagnosis typically starts with clinical suspicion based on developmental delay, intellectual disability, or multisystem findings, followed by biochemical screening for abnormal transferrin glycoforms. Definitive confirmation requires molecular testing—either a targeted COG5 gene sequencing panel or exome/genome sequencing—to identify pathogenic variants.
Currently there is no cure; management is supportive and multidisciplinary. Interventions focus on seizure control, physical and occupational therapy for motor delays, speech therapy, nutritional support, and regular monitoring of liver, cardiac, and coagulation status. Some centers trial oral mannose or other substrate supplementation, but evidence of benefit is limited.
COG5‑CDG is inherited in an autosomal recessive manner. Both parents are typically carriers of one pathogenic COG5 variant. For each subsequent pregnancy, there is a 25 % chance of an affected child, a 50 % chance of a carrier, and a 25 % chance of an unaffected, non‑carrier child. Prenatal carrier testing or pre‑implantation genetic diagnosis can be discussed with a genetics counselor.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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