People affected may have:
- neurological problems such as developmental delay (see entry Global Developmental Delay)
- visual problems such as squint or retinitis pigmentosa
- cerebellar hypoplasia (underdevelopment of the cerebellum in the brain)
- liver disease
- kidney cysts
- heart abnormalities
- abnormal fat distribution under the skin
- patients often have inverted nipples.
A similar range of problems are seen in most other forms of CDG. An exception is PMI-CDG, previously called CDG-Ib.
People affected may have liver disease, diarrhoea and severe failure to thrive. They may have low blood sugar levels due to too much insulin, but they do not have neurological problems.