Clinical Characteristics

The following description of the broad clinical spectrum is based on 20 individuals (Chen et al., 2016).


Growth parameters

Usually normal.


Neurological features

Individuals with BBSOAS have developmental delay and intellectual disability. However, low normal IQ has been described. Neonatal hypotonia is common and oral motor dysfunction is present in about half of the cases. Seizures are variable present, ranging from no epilepsy to infantile spasm to onset of seizures at the age of 18 years. Thinning of the corpus callosum can be present and delayed myelination was reported.  One individual with spasticity was described.


Neuropsychological disorders

Behavioral problems are present in about half of the individuals with BBSOAS, including autism spectrum disorder and/or ADHD. Repetitive behavior is also observed.


Facial dysmorphism

No specific facial dysmorphisms are observed.


Visual and hearing impairments

Many individuals have vision impairment, due to optic nerve atrophy, optic nerve hypoplasia and/or cerebral visual impairment.

Hearing impairment can also be present in persons with BSSOAS.


Congenital abnormalities

Based on the current knowledge there is no increased risk for congenital abnormalities, such as cardiovascular defects, renal or urogenital anomalies, or gastro-intestinal anomalies.