Mutations in FBXL4 gene may cause the following signs and symptoms:
- Weak muscle tone (hypotonia)
- Brain dysfunction (encephalopathy)
- Failure to grow or gain weight at the expected rate
- Delayed motor skills development
- Movement abnormalities
- Impaired speech development
- Seizures
- Microcephaly (smaller-than-normal head)
- Unusual facial features (including broad nasal bridge, a long space between the upper lip and nose, and thick eyebrows)
- Abnormal findings on brain MRI imaging
- Congenital heart defects
- Heart rhythm abnormalities
- Vision problems
- Hearing loss
- Immune deficiency
- Liver disease
- Build-up of a chemical called lactic acid in the body (lactic acidosis)
- Build-up of ammonia in the blood