Neurodevelopmental Disorder With or Without Seizures and Gait Abnormalities
Patient Information
Characteristics
Background and History
This is one of a large number of neurological conditions resulting from DNA changes (mutations) that impact the development of the nervous system.
Clinical Correlations
There is wide variability in severity of clinical signs in this condition. Symptoms of irritability, stiffness in the arms and legs, an increased startle reflex, and sometimes seizures are present in infancy and early childhood. Intellectual disability and gait clumsiness are evident later. However, less severely affected individuals have few movement problems and may be able to attend special education schools. Many patients have little or no speech and are unable to follow simple commands.
Nystagmus (purposeless movements of the eyes) and strabismus (‘crossing’ of the eyes) are often present. There may be underdevelopment of the optic nerves that attach the eye to the brain.
Large ears are the most common external feature. One of 5 reported patients was noted to be short in stature. Feeding and sleeping problems with purposeless hand movements are more common. Imaging of the brain in one individual revealed underdevelopment of brain structures.
Genetics
Inheritance
This disorder results from mutations in a single specific gene. The nature of the mutation suggests that this is an autosomal dominant disorder but no familial transmission of this condition has been recorded most likely due to the negative impact on reproductive capability.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Diagnosis and Prognosis
The lack of specific diagnostic signs makes diagnosis difficult, especially in infancy and early childhood. However, the pattern of neurological development should lead to DNA analysis and diagnosis. The lack of neurological develop during the first decade of life especially may point towards the general pattern of delayed maturation of the nervous system.
The evaluation and care of these infants and young children requires a multidisciplinary team of pediatricians, neurologists, and ophthalmologists.
No treatment has been reported. Supportive care is required and physical therapy might be beneficial. If feeding problems are a major issue a gastroscopy tube can be placed.
Several patients have survived to adulthood but nothing is known regarding longevity.
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