Exploring the Spectrum of RHOBTB2 Variants Associated with Developmental Encephalopathy 64: A Case Series and Literature Review

Abstract

Background

Rho‐related BTB domain‐containing protein 2 (RHOBTB2) is a protein that interacts with cullin‐3, a crucial E3 ubiquitin ligase for mitotic cell division. RHOBTB2 has been linked to early infantile epileptic encephalopathy, autosomal dominant type 64 (OMIM618004), in 34 reported patients.

Methods

We present a case series of seven patients with RHOBTB2‐related disorders (RHOBTB2‐RD), including a description of a novel heterozygous variant. We also reviewed previously published cases of RHOBTB2‐RD.

Results

The seven patients had ages ranging from 2 years and 8 months to 26 years, and all had experienced seizures before the age of one (onset, 4–12 months, median, 4 months), including various types of seizures. All patients in this cohort also had a movement disorder (onset, 0.3–14 years, median, 1.5 years). Six of seven had a baseline movement disorder, and one of seven only had paroxysmal dystonia. Stereotypies were noted in four of six, choreodystonia in three of six, and ataxia in one case with multiple movement phenotypes at baseline. Paroxysmal movement disorders were observed in six of seven patients for whom carbamazepine or oxcarbazepine treatment was effective in controlling acute or paroxysmal movement disorders. Four patients had acute encephalopathic episodes at ages 4 (one patient) and 6 (three patients), which improved following treatment with methylprednisolone. Magnetic resonance imaging scans revealed transient fluid‐attenuated inversion recovery abnormalities during these episodes, as well as myelination delay, thin corpus callosum, and brain atrophy. One patient had a novel RHOBTB2 variant (c.359G>A/p.Gly120Glu).

Conclusion

RHOBTB2‐RD is characterized by developmental delay or intellectual disability, early‐onset seizures, baseline movement disorders, acute or paroxysmal motor phenomena, acquired microcephaly, and episodes of acute encephalopathy. Early onsets of focal dystonia, acute encephalopathic episodes, episodes of tongue protrusion, or peripheral vasomotor disturbances are important diagnostic clues. Treatment with carbamazepine or oxcarbazepine was found to be effective in controlling acute or paroxysmal movement disorders. Our study highlights the clinical features and treatment response of RHOBTB2‐RD.

Developmental encephalopathies are frequently associated with epilepsy. The term “epileptic encephalopathy” refers to a presumed causal relationship between epilepsy and developmental delay. ¹ However, with 110 genes currently associated with epileptic encephalopathies (see the OMIM phenotypic series at https://www.omim.org/phenotypicSeries/PS308350), the term “developmental and epileptic encephalopathy” (DEE) has been suggested in the last International League Against Epilepsy (ILAE) proposal for epilepsy classification, indicating that both the cause and the epilepsy itself may have relevant implications for the phenotype. Interestingly, some DEEs also manifest movement disorders. ² , ³

Recently described variants in the gene that codes for Rho‐related BTB domain‐containing protein 2 (RHOBTB2) have been found to cause epileptic encephalopathy, early infantile, 64, autosomal dominant (OMIM618004) (Fig. 1). ⁴ , ⁵ , ⁶ The Rho family of small GTPases is a subfamily of the Ras superfamily of GTP‐binding proteins that function as molecular switches, cycling between an active GTP‐bound state and an inactive GDP‐bound state. ⁷ RHOBTB2 belongs to the Rho GTPase family and was found to bind to the CUL3 ubiquitin ligase complex ⁸ required for mitotic cell division and to have high expression in the neocortex. ⁹

FIG. 1.

(A) Depicts the reported variants in the RHOBTB2 gene (NM_001160036.2). (B) Presents a graphical illustration of the relevant clinical features of the disease for each patient in both the literature and the present study, distributed by variants.

RHOBTB2 is also significantly expressed beyond the cerebral cortex, encompassing the thalamus and basal ganglia (available at: https://www.proteinatlas.org/ENSG00000008853-RHOBTB2/tissue), potentially contributing to the varied symptomatology observed in RHOBTB2‐related disorders (RHOBTB2‐RD). In addition to epileptic seizures, individuals with RHOBTB2 variants experience acute encephalopathic episodes often triggered by infections, febrile status epilepticus, or minor head trauma. ¹⁰ The impact of RHOBTB2 variants extends beyond epileptic encephalopathy and has been documented in patients with Rett‐like phenotypes, ⁹ alternating hemiplegia of childhood, ¹¹ and severe paroxysmal dyskinesia without seizures. ¹²

This study presents the clinical characterization of seven newly identified patients harboring de novo RHOBTB2 variants, accompanied by a comprehensive review of previously reported cases in the literature. Alongside providing clinical insights for facilitating early diagnosis, we offer treatment recommendations for acute or paroxysmal motor phenomena and acute encephalopathy episodes.

Methods

The patients included in this study were identified from the Movement Disorders Unit at Hospital Sant Joan de Deu, and additional cases were obtained from collaborating neurologists in Latin America and the Spanish RHOBTB2 Association. Data collection for the study was conducted through a retrospective review of clinical records. The methods section is provided in the Supplementary material S1.

Results

Seven patients were included in this study, of which three were female and all were unrelated. At the time of the most recent clinical review, the age of the patients ranged from 2 years and 8 months to 26 years.

Clinical Characteristics

With the exception of patient 4 (P4), all patients were born at term with normal birth weight and head circumference. P4 presented with congenital microcephaly. Mild facial dysmorphism was observed in two patients, whereas five patients had acquired microcephaly. Severe or profound intellectual disability was present in all patients except for P5, who displayed mild to moderate intellectual disability. Two patients, P3 and P6, experienced prominent motor and neurodevelopmental stagnation at 4 and 5 months of age, respectively. Additionally, behavioral abnormalities such as anxiety, autism spectrum disorder (ASD), and aggressivity were also observed. A brief outline of motor and language developmental milestones is shown in Table 1.

TABLE 1.

Clinical, electroencephalographic, and MRI studies of our cohort

	Patient 1	Patient 2	Patient 3	Patient 4	Patient 5	Patient 6	Patient 7
Sex, age	Male, 7 yr	Male, 2 yr 8 mo	Male, 10 yr	Female, 7 yr	Female, 26 yr	Male, 6 yr 7 mo	Female 3 yr 6 mo
RHOBTB2 variant (NM_001160037.1), inheritance	c.1531C > T/p.Arg511Trp, de novo	c.1531C > T/p.Arg511Trp, de novo	c.1531C > T/p.Arg511Trp, de novo	c.1532G > A/p.Arg511Gln, de novo	c.359G > A/p.Gly120Glu, de novo	c.1531C > T/p.Arg511Trp, de novo	c.1448G > A/p.Arg483His, de novo
Intellectual disability	Severe	Severe	Profound‐severe	Severe	Mild–moderate	Severe	Severe
Neurodevelopmental regression or stagnation (age)	No	No	Yes, stagnation at 5 mo	No	No	Yes, stagnation at 4 mo	No
GMFCS	III	V	IV	I	I	IV	V
Speech abilities	Nonverbal	Nonverbal	Nonverbal	Nonverbal	Nonverbal	Nonverbal	Nonverbal
Seizure onset (mo), current seizure control	12, partial	4, partial	5, partial	12, partial	4, seizure‐free (since 17 yr).	4, seizure‐free	2, seizure‐free
Seizure type	Febrile seizures, focal seizures, status epilepticus	Focal onset seizure with motor symptoms	Focal impaired awareness motor clonic seizures, focal to bilateral tonic–clonic seizures, non‐febrile refractory status epilepticus, febrile status epilepticus	Generalized non‐motor seizures	Focal seizures with impaired awareness, febrile seizures	Tonic seizures, tonic asymmetric seizures	Generalized tonic–clonic seizure
Acute encephalopathy, age at onset, duration, and treatment	Yes, 4 yr, <24 h, MTP	No	No	Yes, 6 yr, 24 h, propofol and hypertonic saline	Yes, 6 yr, unknown duration, BZD, DXM, barbituric, dantrolene	Yes, 6 yr, <24 h, MTP	No
MD onset (yr)	1	0,3	3	1,5	14	2	0,4
Baseline MD	Stereotypes	Choreodystonia	Ataxia, choreodystonia, stereotypes	Stereotypes	Stereotypes	No	Choreodystonia, stereotypies
Acute or paroxysmal MD	Kinesigenic paroxysmal dyskinesia	Paroxysmal dystonia, dyskinetic crisis	Paroxysmal dystonia	Paroxysmal dystonia	Paroxysmal ataxia, paroxysmal diplegia and hemiplegia	Paroxysmal dystonia	No
Trigger of paroxysmal MD	Beginning of the walk	Anxiety, abdominal discomfort, infections, sedation	VGB, fever, infections, minor head trauma, excitement, fatigue	No	Anxiety and sedation	Excitement, exposure to water	No
MD treatment and response	OXC, good response	OXC, moderate response	ESL and CBD, good response	No	No	OXC, good response	No
Brain MRI	Left cortical alteration in FLAIR, left hippocampal atrophy, thin CC	Normal	Cerebellar and brain atrophy	Myelination delay	Right temporoparietal T2W hypersignal, suspected ischemic origin	Thin CC and reduced volume of supratentorial WM, bilateral perysylvian diffusion restriction on DWI‐ADC	Brain atrophy

Abbreviations: MRI, magnetic resonance imaging; yr, year; mo, month; GMFCS, gross motor functional classification system; h, hour; BZD, benzodiazepines; MTP, methylprednisolone; DXM, dexamethasone; MD, movement disorders; VGB, vigabatrin; FLAIR, fluid‐attenuated inversion recovery; CC, corpus callosum; WM, white matter.

All patients experienced seizures, typically starting between 4 and 12 months of age, with focal seizures being the most common initial type. Notably, P1 and P3 presented with status epilepticus. Four patients responded positively to treatment with topiramate, oxcarbazepine, eslicarbazepine, or carbamazepine. However, the ketogenic diet administered to P3 did not prove effective, whereas the use of cannabidiol led to more favorable outcomes. Some patients achieved partial seizure control, whereas others, such as P5, P6, and P7, have remained seizure‐free for varying periods. The Supplementary material S1 contains the video‐electroencephalography findings of all patients.

Patients in this study exhibited baseline movement disorder or acute or paroxysmal motor phenomena starting between 4 months and 14 years of age (Table 1, Videos 1, 2, 3). The baseline movement disorder included choreodystonia, ataxia, and/or stereotypies. One case presented with choreodystonia and stereotypies, whereas another case presented with ataxia and choreodystonia. The remaining cases presented with stereotypies only, and one patient did not present any baseline movement disorders. Acute or paroxysmal motor phenomena included paroxysmal dystonia in three cases, kinesigenic paroxysmal dyskinesia in one case, and paroxysmal ataxia, diplegia, and hemiplegia in one case. One case presented a dyskinetic crisis. In the majority of cases, the duration of the dyskinetic episodes ranged from 30 s to 1 min. One patient did not show any acute or paroxysmal motor phenomena. These acute or paroxysmal motor phenomena were triggered by various factors, including vigabatrin, fever, infection, mild head trauma, excitement, fatigue, and stressful situations.

Video 1.

Patient 1. (A) Generalized choreodystonia, including facial dyskinesias, is visible on video. (B,C) Additionally, the video depicts generalized dyskinetic movements, including orolingual dyskinesias. (D,E) Generalized dystonia, lasting a few seconds, is observed with greater involvement of the right upper extremity and the left lower extremity. The patient is screaming, and these episodes are painful.

Video 2.

Patient 2. (A) The video depicts the right hand in a dystonic position while feeding. These were the first events of abnormal movement that the parents reported. (B) The patient shows continuous orolingual dyskinesias in this segment of the video. (C) During feeding, this segment of the video also shows dystonic postures of both upper extremities with clenched fists. Additionally, a brief generalized tremor is observed. The episode is painful, and at the conclusion of this segment, both lower limbs are observed in dystonic extension postures. (D) Another episode of generalized dystonia is observed in the patient with flexion of the upper extremities and extension of the lower extremities. (E) Following the resolution of the previous episode, general choreodystonia, including facial chorea, is observed.

Video 3.

(A) Patient 4 exhibits epileptic seizures, which consist of a sudden and brief (seconds) upward elevation of the gaze without loss of contact with the environment. (B) While eating, focal dystonia is observed in the right hand. (C) Painful episode of paroxysmal generalized dystonia.

In Video 1, multiple episodes of paroxysmal dyskinesias of P1 are evident, encompassing generalized acute and paroxysmal choreodystonic movements as well as orolingual dyskinesias. In segments Video 1D,E, another episode is observed, starting as focal dystonia and later becoming generalized. This episode is notable for its painful presentation, which is uncommon in childhood dystonias. In Video 2, focal dystonia is observed as one of the initial manifestations of P2, occurring during feeding, which is a rare occurrence in infants of this age. In segment Video 2B, episodes of tongue protrusion or tongue dyskinesia are evident, with no other associated abnormal movements observed in other body regions. In Video 3, other paroxysmal motor phenomena are depicted, including upward gaze deviation, focal dystonia while feeding, and paroxysmal dyskinesia.

The cohort showed varying responses to treatment: oxcarbazepine was associated with a good response in two cases and a moderate response in one case; eslicarbazepine and cannabidiol were associated with a good response in one case each. Three cases did not receive any treatment. Videos 1, 2, 3 provide a highly descriptive depiction of the movement disorders exhibited by these patients.

Four patients (P1, P4, P5, and P6) experienced acute encephalopathy episodes at 4 and 6 years of age and were treated with corticosteroids, including methylprednisolone and dexamethasone, with a positive response. Hemiparesis was observed in three patients during the acute encephalopathy episodes. The duration of acute encephalopathy episodes lasted up to 24 h where this information was available.

P1 had an episode triggered by fever at 4 years of age, causing right hemiparesis and extensive cortical signal alteration in the left hemisphere, as revealed by magnetic resonance imaging (MRI). P4 experienced low consciousness and hypotonia after a mild head injury, but recovered completely within 24 h after treatment with hypertonic saline. P5 had an episode of acute encephalopathy at 6 years of age, resulting in seizures, syndrome of inappropriate secretion of antidiuretic hormone, hyperthermia, and left hemiparesis. A brain MRI showed ischemic lesions in the right parietotemporal region. The patient was treated with carbamazepine and clonazepam and achieved complete recovery. Finally, P6 had an episode of acute encephalopathy with right hemiparesis, treated with methylprednisolone. MRI showed left‐hemisphere fluid‐attenuated inversion recovery (FLAIR) signal change, left hippocampal atrophy, and a thin corpus callosum. A lumbar puncture revealed positive polymerase chain reaction for herpesvirus type 6 (HHV‐6), suggesting possible involvement. Identifiable triggers for acute encephalopathy in this cohort were mild head trauma and a possible infection with HHV‐6. In cases with subsequent brain MRIs, these acute radiological abnormalities completely disappeared.

In addition, peripheral vasomotor disturbances (generalized episodic erythema or pallor) and oculomotor apraxia were observed in one patient each. Brain MRIs revealed myelination delay, a thin corpus callosum, and brain atrophy. Further clinical, electroencephalographic, and neuroimaging data, as well as a detailed clinical course, are summarized in Table 1 and Supplementary Material S1.

Genotype

All variants considered in this study were identified through whole exome sequencing (WES), except for P6, which was detected using a gene panel. The genotypes of the cohort include c.1531C>T/p.Arg511Trp (four patients), c.359G>A/p.Gly120Glu, c.1448G>A/p.Arg483His, and c.1532G>A/p.Arg511Gln (one patient each) (Fig. 1). In the case of variant (NM_001160037.2):c.314G>A/p.Gly105Glu, it has been re‐annotated with transcript (NM_001160036.2) to now read c.359G>A/p.Gly120Glu. All of these variants were inherited de novo. The novel variant c.359G>A/p.Gly120Glu is predicted to be a variant of uncertain significance (VUS), based on the following American College of Medical Genetics and Genomics criteria: PM2 and PP3. The position of the variant is strongly conserved, and it was not found in GnomAD exomes or genomes. Additionally, Mutation Taster and PROVEAN classified this variant as uncertain and pathogenic, respectively. The Combined Annotation Dependent Depletion score for this variant is 27.0.

Literature Review

Therefore, 34 patients have been identified and documented in the literature (Fig. 1 and 2). ⁴ , ⁵ , ⁶ , ⁹ , ¹⁰ , ¹¹ , ¹² , ¹³ , ¹⁴ , ¹⁵ , ¹⁶ The comprehensive analysis of the literature review can be accessed within the Supplementary material S2.

FIG. 2.

Depicts the relevant clinical features of the 41 patients that have been reported in the existing literature, as well as those individuals that are included in the current article.

Discussion

The current study delineates the clinical presentation of seven previously unreported patients with RHOBTB2 de novo variants, with four of them carrying the c.1531C>T/p.Arg511Trp variant. RHOBTB2‐RD are distinct from other developmental disorders in their manifestation of acute encephalopathic episodes, paroxysmal or acute motor phenomena, including hemiplegic attacks, tongue protrusion or dyskinesia, painful focal dystonia, and peripheral vasomotor disturbances.

Distinguishing between epileptic seizures and non‐epileptic paroxysmal motor phenomena posed a challenge in this cohort, similar to ATP1A3‐related disorders. ¹⁷ Diagnostic difficulties were encountered with paroxysmal upward gaze deviation, tongue protrusion or dyskinesias, and focal dystonia (isolated upper limb stiffness), among other phenomena.

Remarkably, we have identified focal dystonia in young children as a valuable clinical indicator for diagnosing RHOBTB2‐RD. Focal dystonia has also been reported in other developmental and epileptic encephalopathies, such as ARX ¹⁸ , ¹⁹ and ATP1A3. ²⁰ In the latter disorder, episodes of unilateral or asymmetric arm posturing were observed clinically similar to RHOBTB2‐RD, including pain, although they appeared at an older age compared to RHOBTB2‐RD. Our findings suggest that treatment with oxcarbazepine or carbamazepine significantly reduces acute or paroxysmal motor phenomena, indicating their potential benefit in managing RHOBTB2‐RD in children with frequent motor phenomena. The specific mechanism underlying the dramatic response to carbamazepine or oxcarbazepine for movement disorders and corticosteroids for encephalopathic crises in RHOBTB2‐RD is not completely understood. It is plausible that the RHOBTB2 gene and its protein product play a role in regulating ion channels and membrane excitability in neurons, ²¹ which could be modulated by carbamazepine or oxcarbazepine (Fig. 3).

FIG. 3.

Summarizes the most relevant aspects of RHOBTB2‐related disorders. The figure also includes the suggested treatment options for acute/paroxysmal movement disorders with oxcarbazepine (OXC) or carbamazepine (CBZ) and acute encephalopathic attacks with methylprednisolone. ASD, autism spectrum disorder; ID, intellectual disability; MD, movement disorders, MP, motor phenomena.

Acute encephalopathy episodes are uncommon in developmental and epileptic encephalopathies, but have been reported in SZT2, ²² SCN1A, ²³ , ²⁴ and HNRNPU ²⁵ patients, often associated with intractable epilepsy or status epilepticus. In some SCN1A patients with acute encephalopathy, diffusion‐weighted images have revealed two distinct types of brain lesions, those predominantly affecting the cerebral cortex, with or without deep gray matter involvement, and those primarily affecting the subcortical regions. Similarly, in RHOBTB2‐RD, lesions have mainly been observed in the cerebral cortex. However, the acute episodes tend to have a less severe outcome in RHOBTB2‐RD patients compared to SCN1A patients, with nearly complete recovery following the episodes. These observations suggest that RHOBTB2 variants may predispose individuals to acute encephalopathy induced by infections or trauma. Further research is needed to establish whether patients with the RHOBTB2:c.1532G>A variant are at a higher risk of developing these episodes.

The differential diagnosis of acute encephalopathy in RHOBTB2‐RD should consider not only developmental and epileptic encephalopathies, but also metabolic disorders ²⁶ and channelopathies. ²⁷ Various triggers have been associated with acute or paroxysmal movement disorders in RHOBTB2‐RD, including fever, infection, mild head trauma, and stressful situations. However, the specific triggering factor for acute encephalopathy remains unknown in most cases. In this study, we present a case where HHV‐6 infection may have acted as a trigger, but its significance remains uncertain because of overlapping symptoms with the underlying genetic disease and incomplete fulfillment of the criteria described by Ward et al. ²⁸ , ²⁹ Furthermore, one case exhibited a worsening of movement disorders with vigabatrin, but there is insufficient information or experience to explain this observation. Fong et al ³⁰ reported that vigabatrin was associated with movement disorder development in two of eight cases of children with infantile spasms. This suggests that vigabatrin may reveal an underlying predisposition to movement disorders, as it amplifies the inhibitory neurotransmitter GABA. GABA deficiency in the central nervous system has been linked to various movement disorders and the development of spasticity.

Corticosteroid treatment has shown a positive response in RHBOTB2‐RD, and its use should be considered in severe encephalopathy episodes. Similarly, corticosteroids have also been used for encephalopathic episodes in other DEEs, such as SCN2A. ³¹ Establishing a well‐defined management plan for acute encephalopathy in RHBOTB2‐RD is crucial, including hospital admissions, close airway monitoring, and systematic assessment of neurological status based on the Glasgow Coma Scale.

Considering similar genetic disorders is crucial for achieving an accurate diagnosis and appropriate management of RHOBTB2‐RD. Several genes, such as G‐protein coupled receptors (GPCRs)‐cAMP pathway genes (eg, GNAO1), ATP1A3, and CACNA1A, share significant similarities with RHOBTB2‐RD, despite the broad range of differential diagnoses. Features like oromandibular involvement, choreodystonic episodes, or dyskinetic crises, and manual or midline stereotypies are characteristic of GNAO1 and other GPCR‐cAMP pathway genes. ² ATP1A3 is associated with paroxysmal cyanosis and an alternating hemiplegia of the childhood phenotype, ³² whereas CACNA1A and ATP1A3 have been linked to encephalopathy triggered by head trauma. ²⁷ It is worth noting that P5 fulfills the diagnostic criteria for hemiplegia of childhood (AHC), including all essential criteria, one major criterion (various types of episodes), and all minor criteria. ³²

Regarding neuroimaging, only one patient in our cohort (P5 with the p.Gly120Glu variant) exhibited the right temporoparietal T2W hypersignal that has been observed in other patients with variants in the RHOBTB2 gene such as p.Arg511Trp, ⁶ p.Arg511Gln, ¹⁰ p.Arg483His, ⁴ , ¹⁰ and p.Arg507Cys. ⁴ These patients were affected by hemiplegia or status epilepticus, suggesting that these radiological changes are not specific to a particular genotype. In the context of imaging findings, it is noteworthy that this patient exhibited contralateral FLAIR changes. We emphasize this finding, given that it is a feature that distinguishes this group from the commonly recognized ATP1A3‐related alternating hemiplegia. The lack of a vascular pattern of distribution of MRI abnormalities could also raise the differential diagnosis with stroke and stroke‐like episodes in inborn errors of metabolism, primarily in mitochondrial diseases, but also in other disorders such as homocystinuria and cobalamin‐related remethylation disorders, congenital disorders of glycosylation, and other neurometabolic disorders. In this regard, clinical data such as the presence of multi‐organ involvement and metabolic and/or lactic acidosis, along with the frequent involvement of the basal ganglia rather than just the cerebral cortex, would distinguish them from RHOBTB2‐RD. ²⁶

Peripheral vasomotor disturbances are uncommon in developmental and epileptic encephalopathies. Mutations in the SCN9A gene are implicated in primary erythromelalgia, an autosomal dominant disorder characterized by episodes of burning pain, redness, and heat in the extremities. ³³ This could be attributed to the expression of the SCN9A gene in both sensory and sympathetic neurons. However, unlike primary erythromelalgia, there is no apparent association between vasomotor phenomena and burning pain in individuals with RHOBTB2 mutations.

The main limitation of this study is the retrospective nature of data collection over an extended period of time. Future studies could investigate potential changes in seizure patterns before the onset of acute encephalopathy episodes, as seen in patients with SCN1A mutations.

In summary, our study provides evidence that de novo missense mutations in RHOBTB2 are associated with DEE, characterized by early‐onset seizures, paroxysmal motor phenomena, intellectual disability, and developmental delay. This supports the idea that RHOBTB2 deficiency can result in a neurological phenotype. Treatment with carbamazepine or oxcarbazepine has been found to improve seizure control and, furthermore, movement disorders, whereas corticosteroids (methylprednisolone) were effective in treating acute encephalopathy episodes. Our study also identifies a novel variant, c.359G>A/p.Gly120Glu, as well as a recurrent mutation hotspot in c.1531C>T/p.Arg511Trp, adding to the five previously reported cases. Further case reports of patients with this recurrent variant are needed to better understand the specific phenotype associated with it.

Author Roles

(1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript: A. Writing of the First Draft, B. Review and Critique.

S.d.P.B.: 1A, 1C.

A.S.J.: 1C, 3B.

P.C.: 1C, 3B.

F.J.L.G.: 1C, 3B.

R.S.C.: 1C, 3B.

A.C.: 1C, 3B.

M.T.: 1C, 3B.

S.W.: 1C, 3B.

A.B.: 1C, 3B.

C.F.: 1C, 3B.

F.L.P.: 1C, 3B.

J.D.O.E.: 1A, 1B, 1C, 3A, 3B.

Disclosures

Ethical Compliance Statement: The legal guardians gave their written consent to the recording of the patients for publication and the study received ethical approval by the Ethics Committee (ART‐08‐22). We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflicts of Interest: No specific funding was received for this work. The authors declare that there are no conflicts of interest relevant to this work. The authors declare that there are no additional disclosures to report.

Financial Disclosures for the Previous 12 Months: The authors declare that there are no additional disclosures to report.

Supporting information

Supplementary material S1. (A) Detailed clinical, electroencephalographic, and magnetic resonance imaging studies of the seven RHOBTB2 patients. (B) Methods (C) Literature review.

Supplementary material S2. Clinical, electroencephalographic, and magnetic resonance imaging studies of the 30 RHOBTB2 patients that were previously published.