Severity of GNAO1-Related Disorder Correlates with Changes in G-Protein Function.

OBJECTIVE: GNAO1-related disorders (OMIM #615473 and #617493), caused by variants in the GNAO1 gene, are characterized by developmental delay or intellectual disability, hypotonia, movement disorders, and epilepsy. Neither a genotype-phenotype correlation nor a clear severity score have been established for this disorder. The objective of this prospective and retrospective observational study was to develop a severity score for GNAO1-related disorders, and to delineate the correlation between the underlying molecular mechanisms and clinical severity. METHODS: A total of 16 individuals with GNAO1-related disorders harboring 12 distinct missense variants, including four novel variants (p.K46R, p.T48I, p.R209P, and p.L235P), were examined with repeated clinical assessments, video-electroencephalogram monitoring, and brain magnetic resonance imaging. The molecular pathology of each variant was delineated using a molecular deconvoluting platform. RESULTS: The patients displayed a wide variability in the severity of their symptoms. This heterogeneity was well represented in the GNAO1-related disorders severity score, with a broad range of results. Patients with the same variant had comparable severity scores, indicating that differences in disease profiles are not due to interpatient variability, but rather, to unique disease mechanisms. Moreover, we found a significant correlation between clinical severity scores and molecular mechanisms. INTERPRETATION: The clinical score proposed here provides further insight into the correlation between pathophysiology and phenotypic severity in GNAO1-related disorders. We found that each variant has a unique profile of clinical phenotypes and pathological molecular mechanisms. These findings will contribute to better understanding GNAO1-related disorders. Additionally, the severity score will facilitate standardization of patients categorization and assessment of response to therapies in development. ANN NEUROL 2023;94:987-1004.

POSTERIOR CORTEX SEIZURES - PEDIATRIC CHALLENGES.

Posterior cortex seizures have a complex semiologic presentation that is especially challenging in the pediatric population. Therefore, using clinical presentation in localizing ictal involvement is not sufficient in children, thus making this type of epilepsy quite under-recognized. As most of the ictal symptoms are subjective and could well be overshadowed by symptoms arising from adjacent cortices, primarily temporal and central ones, it is necessary not to overlook this large source of pharmacoresistant epilepsies. The parietal lobe as part of an extensive synaptic network is a great imitator, thus quite often producing inaccurate localization readings on scalp electroencephalography (EEG) due to very scattered interictal discharges and uninformative ictal recordings. Using direct cortical recordings in delineating the epileptogenic zone is helpful in some cases but even highly experienced epileptologists may erroneously interpret some features as arising from other localizations, especially the frontal lobe. Epilepsy surgery from the posterior quadrant is still quite rare and relatively unsuccessful, especially in non-lesional epilepsies due to elaborate mechanisms of connectivity, misleading semiology, and non-localizing EEG recordings, possibly due to insufficiency of parietal cortex synchronicity. Applying the aforementioned to the pediatric age makes it perhaps the most difficult challenge for a pediatric epileptologist.

Prognostic value of cranial ultrasonography in comparison with magnetic resonance imaging in children with cerebral palsy: a population-based study.

The aim of this population-based study was to evaluate the characteristics of cerebral palsy (CP) in relation to the predominant pattern of the Magnetic Resonance Imaging Classification System (MRICS) that was analogously applied to the neonatal/early infant cranial ultrasound (CUS). The study included children born during the 2004-2007 period from the Croatian part (C28 RCP-HR) of the Surveillance of Cerebral Palsy in Europe (SCPE) CP register. Motor functions, accompanying impairments and brain MRI were evaluated in 227 children, 185 of which also had CUS. Concerning CP types, 56% of children had bilateral spastic, 34% unilateral spastic, 9% dyskinetic and 1% ataxic CP type. Gross Motor Function Classification System (GMFCS) revealed that 62.05% had mild (GMFCS I-III) and 37.85% had severe motor impairment (GMFCS IV-V). CUS showed white matter injury in 60%, gray matter injury in 12%, maldevelopments in 8%, miscellaneous changes in 14%, while 6% were normal; MRI showed significant agreement (κ=0.675, p<0.001). Neuroimaging findings of maldevelopments and predominant gray matter injury were associated with more severe CP, but 7% of children with CP had normal MRI. As we found very good agreement between CUS and MRI findings, CUS is recommended in children at an increased risk of CP if MRI is not available.

Visual impairment in children with cerebral palsy: Croatian population-based study for birth years 2003-2008.

AIM: To evaluate visual impairment (VI) in children with cerebral palsy (CP). METHODS: This population-based study included 419 children from the Surveillance of Cerebral Palsy in Europe (SCPE) C28 RCP-HR - Register of Cerebral Palsy of Croatia born 2003-2008. Vision in children with CP (according to SCPE) was classified as normal or impaired, with the subcategory of severe VI. The proportion of children with VI was assessed in groups with different CP type/subtype, gross and fine motor function, and gestational age (GA). RESULTS: A total of 266 children had some degree of VI (266/400; 66.5%), 134 had normal vision, and data on VI were unknown for 19 children. Severe VI was present in 44 children (44/400; 11%). The proportion of children with VI and severe VI increased with the Gross Motor Function Classification System and Bimanual Fine Motor Function levels. Children with bilateral spastic CP had the highest frequency of severe VI (14.9%). The percentage of severe VI in children with bilateral spastic CP was 53.8% in the group born <28 weeks of GA, 13.3% in the group born 28-31 weeks of GA, 11.1% in the group born 32-36 weeks of GA, and 24.4% in the group born >36 weeks of GA (λ2=4.95; df=6; P<0.001). CONCLUSION: Children with CP have a high prevalence of VI and severe VI, which is increasing with the level of motor impairment. Severe VI is significantly more common in children with bilateral spastic CP, especially among extremely premature infants.