Until two years ago a little was known about a RHOBTB2, a gene encoding Rho-related BTBdomain-containing protein 2, role in neurodevelopment.

A recent studies  (Lopes et al 2016)  identified its possible causative role in Rett like phenotype, more recent papers (Straub et al 2018; Belal et al 2018) designated it as a causative gene for developmental and/or epileptic encephalopathies.

The most constant symptoms of RHOBTB2 encephalopathy includes early-onset seizures, severe to profound intellectual disability (ID), postnatal microcephaly, and movement disorders, a phenotype also observed in CDKL5-, FOXG1-, or SLC2A1- related encephalopathies.

Therefore, diagnosis of RHOBTB2-related developmental and epileptic encephalopathy might rely on whole exome sequencing rather than on a specific clinical suspicion.

However, paper by Straub et al highlights (post-ictal) hemiparesis and secondary MRI anomalies that might be more specifically related to RHOBTB2.

Here we present a case of 6 y.o. boy with RHOBTB2 (c.1532G>A p.(Arg511Gln) related encephalopathy with early (infantile) onset epilepsy, ID, acquired microcephaly and frequent disabling dystonic (non-epileptic) attacks accompanied by hemiparesis as main and constant feature.

Dystonic attacks and hemiplegia were similar to the attacks sometimes observed in Familial Hemiplegic Migraine (FHM).

Moreover the case we present has excellent response to Acetazolamide (AAA), frequently observed in FHM.

Conclusion:

Along with ID, epilepsy and postnatal microcephaly, dystonia attacks with hemiplegia could be the most disabling feature of some cases with RHOBTB2 encephalopathy.

AAA treatment dramatically reduced the attacks.

RHOBTB2 gene should be included in early onset epilepsies as well as dystonia/microcephaly and ID panels.