Novel WWOX deleterious variants cause early infantile epileptic encephalopathy, severe developmental delay and dysmorphism among Yemenite Jews.

The human WW Domain Containing Oxidoreductase (WWOX) gene was originally described as a tumor suppressor gene. However, recent reports have demonstrated its cardinal role in the pathogenesis of central nervous systems disorders such as epileptic encephalopathy, intellectual disability, and spinocerebellar ataxia. We report on six patients from three unrelated families of full or partial Yemenite Jewish ancestry exhibiting early infantile epileptic encephalopathy and profound developmental delay. Importantly, four patients demonstrated facial dysmorphism. Exome sequencing revealed that four of the patients were homozygous for a novel WWOX c.517-2A > G splice-site variant and two were compound heterozygous for this variant and a novel c.689A > C, p.Gln230Pro missense variant. Complementary DNA sequencing demonstrated that the WWOX c.517-2A > G splice-site variant causes skipping of exon six. A carrier rate of 1:177 was found among Yemenite Jews. We provide the first detailed description of patients harboring a splice-site variant in the WWOX gene and propose that the clinical synopsis of WWOX related epileptic encephalopathy should be broadened to include facial dysmorphism. The increased frequency of the c.517-2A > G splice-site variant among Yemenite Jews coupled with the severity of the phenotype makes it a candidate for inclusion in expanded preconception screening programs.

Mutations in AIFM1 cause an X-linked childhood cerebellar ataxia partially responsive to riboflavin.

BACKGROUND: AIFM1 encodes a mitochondrial flavoprotein with a dual role (NADH oxidoreductase and regulator of apoptosis), which uses riboflavin as a cofactor. Mutations in the X-linked AIFM1 were reported in relation to two main phenotypes: a severe infantile mitochondrial encephalomyopathy and an early-onset axonal sensorimotor neuropathy with hearing loss. In this paper we report two unrelated males harboring AIFM1 mutations (one of which is novel) who display distinct phenotypes including progressive ataxia which partially improved with riboflavin treatment. METHODS: For both patients trio whole exome sequencing was performed. Validation and segregation were performed with Sanger sequencing. Following the diagnosis, patients were treated with up to 200 mg riboflavin/day for 12 months. Ataxia was assessed by the ICARS scale at baseline, and 6 and 12 months following treatment. RESULTS: Patient 1 presented at the age of 5 years with auditory neuropathy, followed by progressive ataxia, vermian atrophy and axonal neuropathy. Patient 2 presented at the age of 4.5 years with severe limb and palatal myoclonus, followed by ataxia, cerebellar atrophy, ophthalmoplegia, sensorineural hearing loss, hyporeflexia and cardiomyopathy. Two deleterious missense mutations were found in the AIFM1 gene: p. Met340Thr mutation located in the FAD dependent oxidoreductase domain and the novel p. Thr141Ile mutation located in a highly conserved DNA binding motif. Ataxia score, decreased by 39% in patient 1 and 20% in patient 2 following 12 months of treatment. CONCLUSION: AIFM1 mutations cause childhood cerebellar ataxia, which may be partially treatable in some patients with high dose riboflavin.

Microcephaly, intractable seizures and developmental delay caused by biallelic variants in TBCD: further delineation of a new chaperone-mediated tubulinopathy.

Microtubule dynamics play a crucial role in neuronal development and function, and several neurodevelopmental disorders have been linked to mutations in genes encoding tubulins and functionally related proteins. Most recently, variants in the tubulin cofactor D (TBCD) gene, which encodes one of the five co-chaperones required for assembly and disassembly of α/ß-tubulin heterodimer, were reported to underlie a recessive neurodevelopmental/neurodegenerative disorder. We report on five patients from three unrelated families, who presented with microcephaly, intellectual disability, intractable seizures, optic nerve pallor/atrophy, and cortical atrophy with delayed myelination and thinned corpus callosum on brain imaging. Exome sequencing allowed the identification of biallelic variants in TBCD segregating with the disease in the three families. TBCD protein level was significantly reduced in cultured fibroblasts from one patient, supporting defective TBCD function as the event underlying the disorder. Such reduced expression was associated with accelerated microtubule re-polymerization. Morpholino-mediated TBCD knockdown in zebrafish recapitulated several key pathological features of the human disease, and TBCD overexpression in the same model confirmed previous studies documenting an obligate dependency on proper TBCD levels during development. Our findings confirm the link between inactivating TBCD variants and this newly described chaperone-associated tubulinopathy, and provide insights into the phenotype of this disorder.

Creatine transporter deficiency: Novel mutations and functional studies.

X-linked cerebral creatine deficiency (MIM 300036) is caused by deficiency of the creatine transporter encoded by the SLC6A8 gene. Here we report three patients with this condition from Israel. These unrelated patients were evaluated for global developmental delays and language apraxia. Borderline microcephaly was noted in one of them. Diagnosis was prompted by brain magnetic resonance imaging and spectroscopy which revealed normal white matter distribution, but absence of the creatine peak in all three patients. Biochemical testing indicated normal plasma levels of creatine and guanidinoacetate, but an increased urine creatine/creatinine ratio. The diagnosis was confirmed by demonstrating absent ([14])C-creatine transport in fibroblasts. Molecular studies indicated that the first patient is hemizygous for a single nucleotide change substituting a single amino acid (c.619 C > T, p.R207W). Expression studies in HeLa cells confirmed the causative role of the R207W substitution. The second patient had a three base pair deletion in the SLC6A8 gene (c.1222_1224delTTC, p.F408del) as well as a single base change (c.1254 + 1G > A) at a splicing site in the intron-exon junction of exon 8, the latter occurring de novo. The third patient, had a three base pair deletion (c.1006_1008delAAC, p.N336del) previously reported in other patients with creatine transporter deficiency. These three patients are the first reported cases of creatine transporter deficiency in Israel.

SLC1A4 mutations cause a novel disorder of intellectual disability, progressive microcephaly, spasticity and thin corpus callosum.

Two unrelated patients, presenting with significant global developmental delay, severe progressive microcephaly, seizures, spasticity and thin corpus callosum (CC) underwent trio whole-exome sequencing. No candidate variant was found in any known genes related to the phenotype. However, crossing the data of the patients illustrated that they both manifested pathogenic variants in the SLC1A4 gene which codes the ASCT1 transporter of serine and other neutral amino acids. The Ashkenazi patient is homozygous for a deleterious missense c.766G>A, p.(E256K) mutation whereas the Ashkenazi-Iraqi patient is compound heterozygous for this mutation and a nonsense c.945delTT, p.(Leu315Hisfs*42) mutation. Structural prediction demonstrates truncation of significant portion of the protein by the nonsense mutation and speculates functional disruption by the missense mutation. Both mutations are extremely rare in general population databases, however, the missense mutation was found in heterozygous mode in 1:100 Jewish Ashkenazi controls suggesting a higher carrier rate among Ashkenazi Jews. We conclude that SLC1A4 is the disease causing gene of a novel neurologic disorder manifesting with significant intellectual disability, severe postnatal microcephaly, spasticity and thin CC. The role of SLC1A4 in the serine transport from astrocytes to neurons suggests a possible pathomechanism for this disease and implies a potential therapeutic approach.

The neuropsychological profile of patients with 3-methylglutaconic aciduria type III, Costeff syndrome.

Costeff syndrome is a rare genetic neuro-ophthalmological syndrome consisting of early-onset bilateral optic atrophy along with a progressive complex motor disorder with elevated levels of urinary 3-methylglutaconic acid and 3-methylglutaric acid. While borderline to mild cognitive deficits have been considered to be common in patients with this syndrome, a comprehensive cognitive assessment has never been performed. The aim of the current study was to explore the cognitive profile associated with Costeff syndrome. Sixteen adult patients diagnosed with Costeff syndrome were administered a neuropsychological test battery that was composed of standardized verbal tests adapted for the blind. General intelligence ranged from average to borderline, with a group mean consistent with intact general cognitive functioning (VIQmean = 85, z = -1) in the low-average range of the general population. The auditory immediate and delayed memory indexes were in the average range and were significantly higher than the general cognitive functioning, whereas the working memory index was significantly lower than the general cognitive functioning. Adult patients with Costeff syndrome have intact global cognition and learning abilities and strong auditory memory performance. © 2015 Wiley Periodicals, Inc.

Unilateral rhythmic hand tapping in Rett syndrome: is this stereotypy?

Rett syndrome is a severe neurodevelopmental disorder, with hand stereotypies as a hallmark of the disease. Epilepsy is a frequent comorbidity and is accompanied by centrotemporal spikes on electroencephalogram, but stereotypic movements should not have epileptiform correlates. During routine video-electroencephalographic investigation in 5 Rett syndrome patients, we identified a peculiar type of unilateral, highly rhythmic hand tapping accompanied by contralateral synchronous centrotemporal spikes on electroencephalography. This phenomenon is not consistent with either reflex seizures or hand stereotypies and does not respond to antiepileptic drugs. The electroencephalographic activity probably represents evoked potentials, either somatosensory or motor, whereas the rhythmic activity raises the possibility of a subcortical pacemaker for a stereotypy variant. The phenomenon could be caused by abnormal circuitry among the hyperexcitable somatosensory cortex, motor cortex, and subcortical areas in Rett syndrome. Clinicians should be aware of the nonepileptic nature of this motor behavior and should not attempt to treat it.

Cerebral venous thrombosis in the mediterranean area in children.

Cerebral Venous Sinus (sinovenous) Thrombosis (CSVT) is a serious and rare disorder, increasingly recognized and diagnosed in pediatric patients. The etiology and pathophisiology has not yet been completely clarified, and unlike adults with CSVT, management in children and neonates remains controversial. However, morbidity and mortality are significant, highlighting the continued need for high-quality studies within this field. The following review will highlight aspects of CSVT in the mediteranian area in children.

Outcome of lamotrigine treatment in juvenile myoclonic epilepsy.

OBJECTIVES: To determine the response rate of patients with juvenile myoclonic epilepsy (JME) to lamotrigine (LTG) and identify predictive factors for treatment response. MATERIAL AND METHODS: Medical records of 62 patients with JME were reviewed for demographic, clinical, and EEG parameters. We determined clinical response to LTG and compared LTG responders with non-responders. RESULTS: There were 35 LTG responders (56%) and 27 non-responders (44%). JME patients without generalized tonic clonic seizures (GTCS) responded better to LTG (P = 0.04). Valproic acid (VPA) failure because of adverse events rather than lack of efficacy (P = 0.069) and delay in diagnosis (P = 0.07) showed a tendency toward good response to LTG. CONCLUSIONS: LTG should be considered a drug of first choice for JME patients without GTCS. LTG as second-line treatment after VPA failure seems more appropriate for those patients whose reason for VPA failure is poor tolerability rather than lack of efficacy.

Glatiramer acetate (GA, Copolymer-1) an hypothetical treatment option for Rett syndrome.

Rett syndrome (RTT) is an X-linked dominant postnatal severe and disabling neurodevelopmental disorder which is the second most common cause for genetic mental retardation in girls and the first pervasive disorder with a known genetic basis. The syndrome is primarily caused by mutations in the Methyl CpG binding protein 2 (MECP2) gene on Xq28. Its protein product MeCP2 acts as a transcriptional repressor or activator depending on the target gene associated. Brain derived neurotrophic factor (BDNF) is a neurotrophic factor playing a major role in neuronal survival, neurogenesis and plasticity. It has been identified as a major MeCP2 target through a candidate gene approach and abnormalities in BDNF homeostasis are believed to contribute to the neurologic phenotype and pato-physiology of part of the symptoms in Mecp2 null mice that show progressive deficits in its expression. Based on the presumed role of BDNF in the pathophysiology of Rett syndrome it is reasonable to assume that interventions that will elevate its levels in the brain of RTT patients will be of therapeutic benefit. Glatiramer acetate (GA, Copolymer 1, Copaxone) an immunomodulator with proven safety and efficacy in Multiple Sclerosis has been reported to cause elevated secretion of BDNF both in animal model and in MS patients. Our hypothesis is that continuous treatment of patients with RTT with Glatiramer acetate might lead to an increase in their brain's BDNF content and an improvement in at least part of the syndrome symptomatology while being safe to use and well tolerated in this population. In a pilot preliminary study we have shown that GA cause elevation of BDNF expression up to the level in naïve control mice in several cortical areas in the Mecp2 mutated mouse brain, but as of yet did not examine the behavioral aspects of this elevation.

Updating the profile of C-terminal MECP2 deletions in Rett syndrome.

OBJECTIVES: This study aimed to compare the phenotype of Rett syndrome cases with C-terminal deletions to that of cases with different MECP2 mutations and to examine the phenotypic variation within C-terminal deletions. METHODS: Cases were selected from InterRett, an international database and from the population-based Australian Rett Syndrome Database. Cases (n=832) were included if they had a pathogenic MECP2 mutation in which the nature of the amino acid change was known. Three severity scale systems were used, and individual aspects of the phenotype were also compared. RESULTS: Lower severity was associated with C-terminal deletions (n=79) compared to all other MECP2 mutations (e.g. Pineda scale C-terminals mean 15.0 (95% CI 14.0-16.0) vs 16.2 (15.9-16.5). Cases with C-terminal deletions were more likely to have a normal head circumference (odds ratio 3.22, 95% CI 1.53 - 6.79) and weight (odds ratio 2.97, 95% CI 1.25-5.76). Onset of stereotypies tended to be later (median age 2.5 years vs 2 years, p<0.001 from survival analysis), and age of learning to walk tended to be earlier (median age 1.6 years vs 2 years, p=0.002 from survival analysis). Those with C-terminal deletions occurring later in the region had lower average severity scores than those occurring earlier in the region. CONCLUSION: In terms of overall severity C-terminal deletion cases would appear to be in the middle of the range. In terms of individual aspects of phenotype growth and ability to ambulate appear to be particular strengths. By pooling data internationally this study has achieved the case numbers to provide a phenotypic profile of C-terminal deletions in Rett syndrome.

Multicenter long-term follow-up of children with idiopathic West syndrome: ACTH versus vigabatrin.

BACKGROUND AND PURPOSE: Long-term follow-up of children with idiopathic West syndrome (WS) treated with adrenocorticotropic hormone (ACTH) or vigabatrin. METHODS: Records of 28 normal magnetic resonance imaging (MRI) WS cases were reviewed for seizure development and cognitive outcome in relation to treatment type and lag. RESULTS: Average age at disease onset was 5.5 months, and average lag time to treatment was 25 days. Fourteen patients were treated with ACTH (eight early and six late), and 14 with vigabatrin (without delay). Response rates were 88% for ACTH and 80% for vigabatrin. Short-term outcomes for seizure cessation and electroencephalography normalization were identical between the groups. In the long-term, early ACTH treatment was better than the rest combined. Average follow-up time was 9 years. A normal cognitive outcome was achieved in 100% of the early-ACTH group, 67% of the late-ACTH group and 54% of the vigabatrin group (P = 0.03). Seizures subsequently developed in 54% of the vigabatrin group, in 33% of the late ACTH group, and 0% of the early ACTH group (P < 0.05). CONCLUSIONS: Idiopathic WS with normal MRI is associated with a good cognitive outcome. Early ACTH treatment, administered within 1 month, yields a better cognitive and seizure outcome than vigabatrin or late ACTH.

Novel mutations in the CDKL5 gene, predicted effects and associated phenotypes.

It has been found that CDKL5 gene mutations are responsible for early-onset epilepsy and drug resistance. We screened a population of 92 patients with classic/atypical Rett syndrome, 17 Angelman/Angelman-like patients and six idiopathic autistic patients for CDKL5 mutations and exon deletions and identified seven novel mutations: six in the Rett subset and one in an Angelman patient. This last, an insertion in exon 11, c.903_904 dupGA, p.Leu302Aspfx49X, is associated with a relatively mild clinical presentation as the patient is the only one capable of sitting and walking alone. Of the six mutations, two are de novo missense changes affecting highly conserved aminoacid residues, c.215 T > C p.Ile72Thr and c.380A > G p.His127Arg (present in a mosaic condition) found in two girls with the most severe clinical presentation, while the remaining are the splicing c.145 + 2 T > C and c.2376 + 5G > A, the c.1648C > T p.Arg550X and the MPLA-identified c.162_99del261 mutation. RNA characterisation of four mutations revealed the aberrant transcript of the missense allele (case 2) and not the stop mutation (case 3), but also allowed the splicing mutation (case 1) and the c.-162_99del261 (case 4) to be categorised as truncating. The obtained data reinforce the view that a more severe phenotype is due more to an altered protein than haploinsufficiency. Furthermore, the mutational repertoire of the CDKL5 gene is shown to be expanded by testing patients with phenotypical overlap to Rett syndrome and applying multiplex ligation-dependent probe amplification.

Investigating genotype-phenotype relationships in Rett syndrome using an international data set.

BACKGROUND: Rett syndrome is an uncommon neurodevelopmental disorder with an incidence of 1:9,000 live female births. The principal genetic cause was first reported in 1999 when the association with mutations in the methyl-CpG-binding protein 2 (or MECP2) gene was identified. This study uses data from a large international database, InterRett, to examine genotype-phenotype relationships and compares these with previous findings in a population-based cohort. METHOD: The data set for these analyses was derived from a subset of InterRett cases with subject information collected from the family, the clinician, or both. Individual phenotypic characteristics and clinical severity using three scales were compared among those with eight known recurrent pathogenic MECP2 mutations as well as those with C-terminal deletions (n = 272). RESULTS: Overall, p.R270X and p.R255X were the most severe and p.R133C and p.R294X were the mildest mutations. Significant differences by mutation were seen for individual phenotypic characteristics such as hand use, ambulation, and language. CONCLUSIONS: This multicenter investigation into the phenotypic correlates of MECP2 mutations in Rett syndrome has provided a greater depth of understanding than hitherto available about the specific phenotypic characteristics associated with commonly occurring mutations. Although the modifying influence of X inactivation on clinical severity could not be included in the analysis, the findings confirm clear genotype-phenotype relationships in Rett syndrome and show the benefits of collaboration crucial to effective research in rare disorders.

Comprehensive diagnosis of Rett's syndrome relying on genetic, epigenetic and expression evidence of deficiency of the methyl-CpG-binding protein 2 gene: study of a cohort of Israeli patients.

BACKGROUND: Despite advances in the characterisation of mutations in the MECP2-coding region, a small proportion of classic RTT cases remain without recognisable mutations. OBJECTIVE AND METHODS: To identify previously unknown mutations, a quantitative assay was established, providing estimates of MECP2_e1 and MECP2_e2 expression levels in peripheral blood. A systematic analysis of an Israeli cohort of 82 patients with classic and atypical RTT is presented, including sequence analysis of the MECP2-coding region, MLPA, XCI and quantitative expression assays. RESULTS AND CONCLUSION: A novel mis-sense mutation at ca 453C-->T (pD151E), resulting in a change of a conserved residue at the methyl-binding domain, and a rare GT deletion of intron 1 donor splice site are reported. It is shown that various MECP2 mutations had distinct effects on MECP2 expression levels in peripheral blood. The most significant (p<0.001) reduction in the expression of both MECP2 isoforms was related to the presence of the intron 1 donor splice-site mutation. Using quantitative expression assays, it was shown that several patients with classic and atypical RTT with no mutation findings had significantly lower MECP2 expression levels. Further research on these patients may disclose still elusive non-coding regulatory MECP2 mutations.

Malformations of cortical development with balloon cells: clinical and radiologic correlates.

BACKGROUND: Balloon cells are a key feature of tuberous sclerosis (TS) but are also seen in focal cortical dysplasia (FCD). The authors compare the clinical and MRI characteristics in children with medically refractory localization-related epilepsy who were found to have balloon cells on histology after cortical resections. METHODS: A retrospective review of clinical and MRI data in cases ascertained from a search of pathology records from 1990 until 2000 for those with a diagnosis of FCD or TS. Seventeen patients were identified with malformations of cortical development with balloon cells on histology. Seven had clinical diagnosis of TS and the remaining 10, FCD with balloon cells (FCDBC). RESULTS: Seventy percent of patients with FCDBC (mean follow-up 3.3 years) and 33% of patients with TS (mean follow-up 5.1 years) are seizure free after surgery. There was agreement between the diagnosis based on preoperative MR imaging and on histology in 60% of patients with FCDBC and 71% of patients with TS. Myelin depletion and calcification were noted more frequently in patients with TS. CONCLUSIONS: No significant differences were noted between patients with refractory epilepsy caused by TS or FCDBC. There was a trend toward better postoperative seizure control in the FCDBC group. These two conditions are difficult to distinguish on the basis of MR and histologic appearances. The authors conclude that FCDBC likely represents a phenotypic variation of TS, and as such, all patients with balloon cell dysplasias should be carefully screened for other features of TS to enable appropriate genetic counseling.

Inborn errors of metabolism: a cause of abnormal brain development.

Brain malformations are caused by a disruption in the sequence of normal development by various environmental or genetic factors. By modifying the intrauterine milieu, inborn errors of metabolism may cause brain dysgenesis. However, this association is typically described in single case reports. The authors review the relationship between brain dysgenesis and specific inborn errors of metabolism. Peroxisomal disorders and fatty acid oxidation defects can produce migration defects. Pyruvate dehydrogenase deficiency, nonketotic hyperglycinemia, and maternal phenylketonuria preferentially cause a dysgenetic corpus callosum. Abnormal metabolism of folic acid causes neural tube defects, whereas defects in cholesterol metabolism may produce holoprosencephaly. Various mechanisms have been proposed to explain abnormal brain development in inborn errors of metabolism: production of a toxic or energy-deficient intrauterine milieu, modification of the content and function of membranes, or disturbance of the normal expression of intrauterine genes responsible for morphogenesis. The recognition of a metabolic disorder as the cause of the brain malformation has implications for both the care of the patient and for genetic counseling to prevent recurrence in subsequent pregnancies.

Transient oromotor deficits in children with benign childhood epilepsy with central temporal spikes.

PURPOSE: To describe transient oromotor deficits in benign childhood epilepsy with centrotemporal spikes (BCECTS), an idiopathic age-specific epileptic syndrome with a benign course. METHODS: Five children with BCECTS and intermittent dysarthria and drooling not in the context of typical clinical seizures are presented. RESULTS: The periods of oromotor deficits correlated with increased seizure frequency in all children. Concomitant EEGs that were recorded during periods of dysarthria in four of the children revealed focal electrographic seizures. The reported children did not differ from other patients with BCECTS in any other respect. CONCLUSIONS: Transient oromotor dysfunction is a rare ictal phenomenon that occurs in children with BCECTS with no other unique clinical features.