PGAP2-Related Hyperphosphatasia-Mental Retardation Syndrome: Report of a Novel Patient, Toward a Broadening of Phenotypic Spectrum and Therapeutic Perspectives.

PGAP2 gene has been known to be the cause of "hyperphosphatasia, mental retardation syndrome-3" (HPMRS3). To date, 14 pathogenic variants in PGAP2 have been identified as the cause of this syndrome in 24 patients described in single-case reports or small clinical series with pan-ethnic distribution. We aim to present a pediatric PGAP2-mutated case, intending to further expand the clinical phenotype of the syndrome and to report our experience on a therapeutic approach to drug-resistant epilepsy.We present the clinical, neuroradiological, and genetic characterization of a Caucasian pediatric subject with biallelic pathogenic variants in the PGAP2 gene revealed by next generation sequencing analysis.We identified a subject who presented with global developmental delay and visual impairment. Brain magnetic resonance imaging showed mild hypoplasia of the inferior cerebellar vermis and corpus callosum and mild white matter reduction. Laboratory investigations detected an increase in alkaline phosphatase. At the age of 13 months, he began to present epileptic focal seizures with impaired awareness, which did not respond to various antiseizure medications. Electroencephalogram (EEG) showed progressive background activity disorganization and multifocal epileptic abnormalities. Treatment with high-dose pyridoxine showed partial benefit, but the persistence of seizures and the lack of EEG amelioration prompted us to introduce ketogenic diet treatment.Our case provides a further phenotypical expansion of HPMRS3 to include developmental and epileptic encephalopathy. Due to the limited number of patients reported so far, the full delineation of the clinical spectrum of HPMRS3 and indications for precision medicine would benefit from the description of new cases and their follow-up evaluations.

Sensitive period for the plasticity of alpha activity in humans.

Visual experience is crucial for the development of neural processing. For example, alpha activity development is a vision-dependent mechanism. Indeed, studies report no alpha activity is present in blind adults. Nevertheless, studies have not investigated the developmental trajectory of this activity in infants and children with blindness. Here, we hypothesize that the difference in neural activity of blind compared to sighted subjects is: absent at birth, progressive with age, specifically occipital and linked to a gradual motor impairment. Therefore, we consider spectral power of resting-state EEG and its association with motor impairment indices, in blind subjects and in sighted controls between 0 and 11 years of age. Blind subjects show posterior alpha activity during the first three years of life, although weaker and slower maturing compared to sighted subjects. The first great differentiation between blind and sighted subjects occurs between 3 and 6 years of age. Starting in this period, reduced alpha activity increases the probability of motor impairment in blind subjects, likely because of impaired perception/interaction. These results show that visual experience mediates the neural mechanisms generating alpha oscillations during the first years of life, suggesting that it is a sensitive period for the plasticity of this process.

Novel insights into the clinico-radiological spectrum of phenotypes associated to PIGN mutations.

OBJECTIVES: Autosomic recessive mutations in the PIGN gene have been described in less than 30 subjects to date, in whom multiple congenital anomalies combined with severe developmental delay, hypotonia, epileptic encephalopathy, and cerebellar atrophy have been described as crucial features. A clear-cut neuroradiological characterization of this entity, however, is still lacking. We aim to present three pediatric PIGN mutated cases with an in-depth evaluation of their brain abnormalities. METHODS: We present the neuroradiological, clinical, and genetic characterization of three Caucasian pediatric subjects with pathogenic/likely pathogenic variants in the PIGN gene revealed by Next Generation Sequencing analysis. RESULTS: We identified three subjects (two siblings, one unrelated case) presenting with encephalopathy with early-onset epilepsy, hypotonia, and severe global developmental delay. No additional severe multiple congenital anomalies were detected. Neuroradiological evaluation showed extensive quantitative reduction of white matter, severe and progressive cortical atrophy, with frontal predominance and an anteroposterior gradient, combined with cerebellar and brainstem atrophy. CONCLUSIONS: Our findings broaden and systematize the neuroradiological spectrum of abnormalities in PIGN related encephalopathy. Furthermore, our dataset confirms that mutations in PIGN gene appear to be pan-ethnic and represent an underestimated cause of early-onset encephalopathy.

Paroxysmal tonic eye deviation: an atypical presentation of hypothalamic hamartoma.

Hypothalamic hamartoma is a rare developmental non-neoplastic malformation, often characterised by early onset gelastic seizures and later progressive cognitive and behavioural deterioration. In this case study, we have examined a child who presented with an atypical onset of benign paroxysmal gaze deviation between two to three months of age. The patient subsequently developed gelastic seizures at age 13. Based on the observation that hypothalamic hamartomas do not involve any functional region involved in eye motility, we speculate that both gaze deviation and gelastic seizures are a manifestation of the epileptogenic nature of the hypothalamic hamartoma. [Published with video sequences].

Long-term neuropsychological follow-up and nosological considerations in five patients with continuous spikes and waves during slow sleep.

Continuous spikes and waves during slow sleep (CSWSS) is a well-known EEG pattern that can be associated with cognitive and behavioural deterioration. We present the long-term neuropsychological follow-up and nosological considerations of five patients who developed CSWSS during childhood. All five of our patients presented CSWSS, although the duration and severity of this pattern varied. The outcome was of three basic types: acquired frontal dementia, language deficits and normal. Four of our patients were initially diagnosed with Landau-Kleffner syndrome but have had markedly diverse outcomes in terms of the severity and type of compromise. Our data suggest that the initial diagnosis, according to current nosological categories, has almost no prognostic significance, while the length and the age of onset of CSWSS, the site of epileptiform activity and the individual neuropsychological profile are more useful for identifying the long-term outcome of patients with CSWSS.

Epileptic Encephalopathies with Status Epilepticus during Sleep: New Techniques for Understanding Pathophysiology and Therapeutic Options.

Encephalopathy with status epilepticus during sleep (ESES) is an epileptic encephalopathy, as defined by the International League Against Epilepsy (ILAE) Task Force on Classification and Terminology, that is, a condition in which the epileptic processes themselves are believed to contribute to the disturbance in cerebral function. Clinical manifestations of ESES are heterogeneous: apart from different seizure types, they consist in combinations of cognitive, motor, and behavioural disturbances associated with a peculiar electroencephalographic pattern of paroxysmal activity significantly activated during slow sleep, which culminates in a picture of continuous spikes and waves during sleep (CSWS). The pathophysiological mechanisms underlying this condition are still incompletely understood. Establishing a clear-cut correlation between EEG abnormalities and clinical data, though interesting, is very complex. Computer-assisted EEG analyses especially if combined with functional magnetic resonance imaging (EEG-fMRI) and metabolic neuroimaging have recently emerged as useful approaches to better understand the pathophysiological processes underlying ESES. Treatment of ESES is not just limited to seizures control but it should be focused on controlling neuropsychological outcome through an improvement of the continuous epileptiform activity. General agreement on treatment guidelines is still lacking. Implementation of new techniques might allow a better understanding of the pathophysiology of ESES and could enhance therapeutics options.