Commonalities and distinctions between two neurodevelopmental disorder subtypes associated with SCN2A and SCN8A variants and literature review.

This study was aimed to analyze the commonalities and distinctions of voltage-gated sodium channels, Nav1.2, Nav1.6, in neurodevelopmental disorders.

A complex epileptic and dysmorphic phenotype associated with a novel frameshift KDM5B variant and deletion of SCN gene cluster.

The histone demethylase family plays a key role in chromatin structure and gene regulation during development. Mutations in the genes encoding the lysine demethylase 5 (KDM5) were reported in individuals with many diseases, including neurodevelopmental disorders such as intellectual disability. Recently, KDM5B has been identified as a gene regulator causative of recessive neurodevelopmental disorders.

Recurrent missense variant in the nuclear export signal of FMR1 associated with FXS-like phenotype including intellectual disability, ASD, facial abnormalities.

Fragile X syndrome (FXS; MIM 300624) is an X-linked genetic disorder characterized by physical abnormalities associated with intellectual disability and a wide spectrum of neurological and psychiatric impairments. FXS occurs more frequently in males, 1 in 5000 males and 1 in 8000 females accounting for 1-2% of overall intellectual disability (ID). In more than 99% of patients, FXS results from expansions of a CGG triplet repeat (>200 in male) of the FMR1 gene.

A paradigmatic autistic phenotype associated with loss of PCDH11Y and NLGN4Y genes.

Background: Most studies relative to Y chromosome abnormalities are focused on the sexual developmental disorders. Recently, a few studies suggest that some genes located on Y chromosome may be related to different neurodevelopment disorders.

Case Presentation: We report a child with sexual developmental disorder associated with a peculiar phenotype characterized by severe language impairment and autistic behaviour associated with a mosaicism [45,X(11)/46,XY(89)] and a partial deletion of the short and long arm of Y chromosome (del Yp11.

Broad neurodevelopmental features and cortical anomalies associated with a novel de novo KMT2A variant in Wiedemann-Steiner syndrome.

Wiedemann-Steiner syndrome (WDSTS) is a rare genetic disorder including developmental delay/intellectual disability (DD/ID), hypertrichosis cubiti, short stature, and distinctive facial features, caused by mutation in KMT2A gene, which encodes a histone methyltransferase (H3K4) that regulates chromatin-mediated transcription. Different neurodevelopmental phenotypes have been described within the WDSTS spectrum, including a peculiar Autism Spectrum Disorder (ASDs) subtype in some affected individuals. Here, we report a 9-year-old Caucasian male found by next-generation panel sequencing to carry a novel heterozygous de novo KMT2A frameshift variant (NM_001197104.

Benign familial infantile epilepsy associated with KCNQ3 mutation: a rare occurrence or an underestimated event?

Benign familial infantile epilepsy (BFIE) is the most genetically heterogeneous phenotype among early-onset familial infantile epilepsies. It has an autosomal dominant inheritance pattern with incomplete penetrance. Although PRRT2 is the most mutated gene detected in families with BFIE, other mutations in KCNQ2, SCN2A, and GABRA6 genes have also been described.

Two distinct phenotypes, hemiplegic migraine and episodic Ataxia type 2, caused by a novel common CACNA1A variant.

Background: To investigate the genetic and environmental factors responsible for phenotype variability in a family carrying a novel CACNA1A missense mutation. Mutations in the CACNA1A gene were identified as responsible for at least three autosomal dominant disorders: FHM1 (Familial Hemiplegic Migraine), EA2 (Episodic Ataxia type 2), and SCA6 (Spinocerebellar Ataxia type 6). Overlapping clinical features within individuals of some families sharing the same CACNA1A mutation are not infrequent.

Age-dependent epileptic encephalopathy associated with an unusual co-occurrence of ZEB2 and SCN1A variants.

Mowat-Wilson syndrome is a genetic disorder associated with a variable phenotype including peculiar facial features associated with intellectual disability, epilepsy, language impairment, and multiple congenital anomalies caused by heterozygous mutation of the ZEB2 gene. The ZEB2 protein is a complex transcription factor that encompasses multiple functional domains that interact with the regulatory regions of target genes including those involved in brain development. Recently, it has been documented that ZEB2 regulates the differentiation of interneuron progenitors migrating from the medial ganglionic eminence to cortical layers by repression of the Nkx2-1 homeobox transcription factor.

A novel mutation in KCNQ3-related benign familial neonatal epilepsy: electroclinical features and neurodevelopmental outcome.

Benign familial neonatal epilepsy (BFNE) is caused, in about 5% of families, by mutations in the KCNQ3 gene encoding voltage-gated potassium channel subunits. Usually, newborns with BFNE show a normal neurological outcome, but recently, refractory seizures and/or developmental disability have been reported suggesting phenotype variability associated with KCNQ3-related BFNE. Here, we describe a proband from a BFNE family carrying a novel variant in the KCNQ3 gene.

A novel mutation of WDR62 gene associated with severe phenotype including infantile spasm, microcephaly, and intellectual disability.

The autosomal recessive form of primary microcephaly (MCPH) is a rare disorder characterized by head circumference of at least 3 standard deviation below the mean. The MCPH exhibits genetic heterogeneity with thirteen loci (MCPH1-MCPH13) identified, and associated with variable degree of intellectual disability. It has been reported that WDR62 is the second causative gene of autosomal recessive microcephaly (MCPH2) playing a significant role in spindle formation and the proliferation of neuronal progenitor cells.

A novel KCNQ3 mutation in familial epilepsy with focal seizures and intellectual disability.

Mutations in the KCNQ2 gene encoding for voltage-gated potassium channel subunits have been found in patients affected with early onset epilepsies with wide phenotypic heterogeneity, ranging from benign familial neonatal seizures (BFNS) to epileptic encephalopathy with cognitive impairment, drug resistance, and characteristic electroencephalography (EEG) and neuroradiologic features. By contrast, only few KCNQ3 mutations have been rarely described, mostly in patients with typical BFNS. We report clinical, genetic, and functional data from a family in which early onset epilepsy and neurocognitive deficits segregated with a novel mutation in KCNQ3 (c.

Variable phenotype in 17q12 microdeletions: clinical and molecular characterization of a new case.

Microdeletions of 17q12 including the hepatocyte nuclear factor 1 beta (HNF1B) gene, as well as point mutations of this gene, are associated with the Renal Cysts and Diabetes syndrome (RCAD, OMIM 137920) and genitourinary alterations. Also, microdeletions encompassing HNF1B were identified as a cause of Mayer-Rokitansky-Küster-Hauser Syndrome (MRKH, OMIM 277000) in females and, recently, were associated with intellectual disability, autistic features, cerebral anomaly and facial dysmorphisms. In this report, we describe a boy with a deletion in 17q12 region detected by SNP array, encompassing the HNF1B gene, that showed dysmorphic features, intellectual disability (ID), serious speech delay and autistic features.

Benign nocturnal alternating hemiplegia of childhood: a new case with unusual findings.

It has been described a neuro developmental disorder labelled "Benign nocturnal alternating hemiplegia of childhood" (BNAHC) characterized by recurrent attacks of nocturnal hemiplegia without progression to neurological or intellectual impairment. We report a female patient who at 11months revealed a motionless left arm, unusual crying without impairment of consciousness and obvious precipitating factors. The attacks occur during sleep in the early morning with lack of ictal and interictal electroencephalographic abnormalities, progressive neurological deficit, and cognitive impairment.

West syndrome followed by juvenile myoclonic epilepsy: a coincidental occurrence?

Background: West syndrome is an age-dependent epilepsy with onset peak in the first year of life whose aetiology may be symptomatic or cryptogenic. Long-term cognitive and neurological prognosis is usually poor and seizure outcome is also variable. Over the past two decades a few patients with favourable cognitive outcome and with total recovery from seizures were identified among the cryptogenic group suggesting an idiopathic aetiology.

Benign myoclonic epilepsy in infancy followed by childhood absence epilepsy.

Benign myoclonic epilepsy in infancy (BMEI) is a rare syndrome included among idiopathic generalized epilepsies (IGE) and syndromes with age-related onset. Recently, it has been shown that a few patients with BMEI later had other epilepsy types mainly IGE but never childhood absence epilepsy (CAE). We report a patient who at 11 months of age showed isolated myoclonic jerks occurring several times a day.

Benign myoclonic epilepsy in infancy: neuropsychological and behavioural outcome.

Benign myoclonic epilepsy in infancy (BMEI) is a rare syndrome of idiopathic generalized epilepsies with onset below 3 years of age. It has been reported that BMEI is associated with a good prognosis, however, recently some studies suggest less favourable neuropsychological outcome. We report a long-term follow-up of seven patients with BMEI.

Non-convulsive status epilepticus associated with tiagabine in a pediatric patient.

We report a 4-year-old patient who developed non-convulsive status epilepticus (NCSE) following tiagabine (TGB) as add-on treatment for refractory partial seizures. NCSE occurred while the patient received TGB 0.83 mg/kg/day.