Main clinical features

BSSOAS is a multisystem disorder characterized by developmental delay, intellectual disability, autism spectrum disorder, muscle weakness (hypotonia), seizures, thinning of the corpus callosum, vision disorders (optic atrophy and cerebral visual impairment) and hearing disorder.



The prevalence of the disorder is yet unknown.



BBSOAS, caused by a microdeletion or a mutation of NR2F1, is inherited in an autosomal dominant manner, but to date almost all cases result from a de novo deletion or NR2F1 mutation. However, transmission from an affected parent is reported (Chen et al., 2016).

Thus, most affected individuals represent simplex cases, i.e., a single occurrence in a family. The recurrence risk for future pregnancies is low (probably <1%) but greater than that of the general population because of the possibility of germline mosaicism in one of the parents.