This is a severe, hereditary, progressive disorder that has widespread neurological signs. It is part of a group of somewhat similar conditions generally named for the parts of the brain primarily involved. Before the availability of advanced DNA analyses, infants and children with these illnesses were often considered to have cerebral palsy.
Infants at birth are usually small and their muscles have poor tone and are sometimes called ‘floppy’. They have difficulty holding their heads and sitting up. Later the muscles are more rigid and tendon reflexes become hyperactive. The skull is small (microcephaly) and the back of the head can appear flattened. The ears are low-set, the eye openings are wide, and the cheeks appear full. Many individuals have seizures. Some infants and children have wasting of the optic nerves (atrophy) resulting in poor vision but quantitative vision levels are unknown. General developmental delay (both physical movements and cognitive skills) are common. Large joints such as the elbows and knees may develop contractures.
Many of the general and specialized brain structures are abnormally small including the cerebellum, the cortex, the brainstem, and the corpus callosum. Short stature is common.
Changes (mutations) in a specific gene are responsible. Both members of the same pair must be changed and a child is affected when each of the carrier (normal) parents contribute a single mutation. Such parents can expect that each child has a 25% risk of inheriting both mutations.
The diagnosis is likely to be made by a pediatrician or a pediatric neurologist. There is no specific treatment for this condition and treatment is supportive only. Longevity is usually shortened to several years or less.