WDR81 mutations cause extreme microcephaly and impair mitotic progression in human fibroblasts and Drosophila neural stem cells.

Microlissencephaly is a rare brain malformation characterized by congenital microcephaly and lissencephaly. Microlissencephaly is suspected to result from abnormalities in the proliferation or survival of neural progenitors. Despite the recent identification of six genes involved in microlissencephaly, the pathophysiological basis of this condition remains poorly understood. We performed trio-based whole exome sequencing in seven subjects from five non-consanguineous families who presented with either microcephaly or microlissencephaly. This led to the identification of compound heterozygous mutations in WDR81, a gene previously associated with cerebellar ataxia, intellectual disability and quadrupedal locomotion. Patient phenotypes ranged from severe microcephaly with extremely reduced gyration with pontocerebellar hypoplasia to moderate microcephaly with cerebellar atrophy. In patient fibroblast cells, WDR81 mutations were associated with increased mitotic index and delayed prometaphase/metaphase transition. Similarly, in vivo, we showed that knockdown of the WDR81 orthologue in Drosophila led to increased mitotic index of neural stem cells with delayed mitotic progression. In summary, we highlight the broad phenotypic spectrum of WDR81-related brain malformations, which include microcephaly with moderate to extremely reduced gyration and cerebellar anomalies. Our results suggest that WDR81 might have a role in mitosis that is conserved between Drosophila and humans.

Efficacy of a ketogenic diet in resistant myoclono-astatic epilepsy: A French multicenter retrospective study.

OBJECTIVE: Recent studies have suggested that the early introduction of a ketogenic diet (KD) could improve seizure control in myoclono-astatic epilepsy (MAE). This multicenter study sought to identify the benefits of KD use on seizure control and epilepsy and on developmental outcomes in children with resistant MAE. METHODS: Fifty children who were diagnosed with severe MAE in the French network of Reference Centers for Rare Epilepsies and who were treated with KD between 2000 and 2013 were included in this study. The seizure frequency and EEG recordings were assessed two weeks before KD introduction, 2 and 6 months after, and during the last follow-up, which also included an assessment of developmental outcome. RESULTS: Patients had a median follow up of 52 months (range 13-136) and received 4.3 antiepileptic drugs [2-9] before KD introduction. Fifty-four percent (54%) of our patients were seizure-free after 6 months of KD or more, and 86% experienced more than a 70% seizure reduction after 2 months of KD. Forty-four percent (44%) of them had a clear benefit of early KD treatment (after four AEDs failed). Early KD treatment did not result in a greater seizure reduction (p=0.055), but significantly resulted in remission (p<0.028). Fifty percent of patients with resistant MAE had normal development outcomes. Earlier KD treatment, after three AEDs failed, was correlated with a better cognitive outcome (p<0.01). SIGNIFICANCE: Early introduction of KD treatment in resistant MAE has a strong, persistent anticonvulsant effect with long-term remission and better cognitive outcomes.

Singing abilities in children with Specific Language Impairment (SLI).

Specific Language Impairment (SLI) is a heritable neurodevelopmental disorder diagnosed when a child has difficulties learning to produce and/or understand speech for no apparent reason (Bishop et al., 2012). The verbal difficulties of children with SLI have been largely documented, and a growing number of studies suggest that these children may also have difficulties in processing non-verbal complex auditory stimuli (Corriveau et al., 2007; Brandt et al., 2012). In a recent study, we reported that a large proportion of children with SLI present deficits in music perception (Planchou et al., under revision). Little is known, however, about the singing abilities of children with SLI. In order to investigate whether or not the impairments in expressive language extend to the musical domain, we assessed singing abilities in eight children with SLI and 15 children with Typical Language Development (TLD) matched for age and non-verbal intelligence. To this aim, we designed a ludic activity consisting of two singing tasks: a pitch-matching and a melodic reproduction task. In the pitch-matching task, the children were requested to sing single notes. In the melodic reproduction task, children were asked to sing short melodies that were either familiar (FAM-SONG and FAM-TUNE conditions) or unfamiliar (UNFAM-TUNE condition). The analysis showed that children with SLI were impaired in the pitch-matching task, with a mean pitch error of 250 cents (mean pitch error for children with TLD: 154 cents). In the melodic reproduction task, we asked 30 healthy adults to rate the quality of the sung productions of the children on a continuous rating scale. The results revealed that singing of children with SLI received lower mean ratings than the children with TLD. Our findings thus indicate that children with SLI showed impairments in musical production and are discussed in light of a general auditory-motor dysfunction in children with SLI.

Word Detection in Sung and Spoken Sentences in Children With Typical Language Development or With Specific Language Impairment.

BACKGROUND: Previous studies have reported that children score better in language tasks using sung rather than spoken stimuli. We examined word detection ease in sung and spoken sentences that were equated for phoneme duration and pitch variations in children aged 7 to 12 years with typical language development (TLD) as well as in children with specific language impairment (SLI ), and hypothesized that the facilitation effect would vary with language abilities. METHOD: In Experiment 1, 69 children with TLD (7-10 years old) detected words in sentences that were spoken, sung on pitches extracted from speech, and sung on original scores. In Experiment 2, we added a natural speech rate condition and tested 68 children with TLD (7-12 years old). In Experiment 3, 16 children with SLI and 16 age-matched children with TLD were tested in all four conditions. RESULTS: In both TLD groups, older children scored better than the younger ones. The matched TLD group scored higher than the SLI group who scored at the level of the younger children with TLD . None of the experiments showed a facilitation effect of sung over spoken stimuli. CONCLUSIONS: Word detection abilities improved with age in both TLD and SLI groups. Our findings are compatible with the hypothesis of delayed language abilities in children with SLI , and are discussed in light of the role of durational prosodic cues in words detection.

Social cognition in ADHD: irony understanding and recursive theory of mind.

The main goal of the present study was to characterise the social cognition abilities of French children with ADHD, in terms of their understanding of people's recursive mental states and their irony comprehension. We hypothesised that these children have difficulty understanding second-order false beliefs and ironic remarks, owing to the executive dysfunction that is characteristic of ADHD. We therefore conducted an experiment in which children with ADHD and typically developing matched controls performed second-order false-belief and executive function tasks. They then listened to ironic stories and answered questions about the ironic comments and about the speakers' beliefs and attitudes. The groups differed significantly on second-order theory of mind, irony comprehension and executive functions, confirming that children with ADHD have impaired social cognition.

A subset of genomic alterations detected in rolandic epilepsies contains candidate or known epilepsy genes including GRIN2A and PRRT2.

OBJECTIVES: Rolandic epilepsies (REs) represent the most frequent epilepsy in childhood. Patients may experience cognitive, speech, language, reading, and behavioral issues. The genetic origin of REs has long been debated. The participation of rare copy number variations (CNVs) in the pathophysiology of various human epilepsies has been increasingly recognized. However, no systematic search for microdeletions or microduplications has been reported in RE so far. METHODS: Array comparative genomic hybridization (aCGH) and quantitative polymerase chain reaction (qPCR) were used to analyze the genomic status of a series of 47 unrelated RE patients who displayed various types of electroclinical manifestations. RESULTS: Thirty rare CNVs were detected in 21 RE patients. Two CNVs were de novo, 12 were inherited, and 16 were of unknown inheritance. Each CNV was unique to one given patient, except for a 16p11.2 duplication found in two patients. The CNVs of highest interest comprised or disrupted strong candidate or confirmed genes for epileptic and other neurodevelopmental disorders, including BRWD3, GRIN2A, KCNC3, PRKCE, PRRT2, SHANK1, and TSPAN7. SIGNIFICANCE: Patients with REs showed rare microdeletions and microduplications with high frequency and heterogeneity. Whereas only a subset of all genomic alterations found here may actually participate in the phenotype, the novel de novo events as well as several inherited CNVs contain or disrupt genes, some of which are likely to influence the emergence, the presentation, or the comorbidity of RE. The future screening of cohorts of larger size will help in detecting more de novo or recurrent events and in appreciating the possible enrichment of specific CNVs in patients with RE.

GRIN2A mutations in acquired epileptic aphasia and related childhood focal epilepsies and encephalopathies with speech and language dysfunction.

Epileptic encephalopathies are severe brain disorders with the epileptic component contributing to the worsening of cognitive and behavioral manifestations. Acquired epileptic aphasia (Landau-Kleffner syndrome, LKS) and continuous spike and waves during slow-wave sleep syndrome (CSWSS) represent rare and closely related childhood focal epileptic encephalopathies of unknown etiology. They show electroclinical overlap with rolandic epilepsy (the most frequent childhood focal epilepsy) and can be viewed as different clinical expressions of a single pathological entity situated at the crossroads of epileptic, speech, language, cognitive and behavioral disorders. Here we demonstrate that about 20% of cases of LKS, CSWSS and electroclinically atypical rolandic epilepsy often associated with speech impairment can have a genetic origin sustained by de novo or inherited mutations in the GRIN2A gene (encoding the N-methyl-D-aspartate (NMDA) glutamate receptor α2 subunit, GluN2A). The identification of GRIN2A as a major gene for these epileptic encephalopathies provides crucial insights into the underlying pathophysiology.

Loss of function of KIAA2022 causes mild to severe intellectual disability with an autism spectrum disorder and impairs neurite outgrowth.

Existence of a discrete new X-linked intellectual disability (XLID) syndrome due to KIAA2022 deficiency was questioned by disruption of KIAA2022 by an X-chromosome pericentric inversion in a XLID family we reported in 2004. Three additional families with likely pathogenic KIAA2022 mutations were discovered within the frame of systematic parallel sequencing of familial cases of XLID or in the context of routine array-CGH evaluation of sporadic intellectual deficiency (ID) cases. The c.186delC and c.3597dupA KIAA2022 truncating mutations were identified by X-chromosome exome sequencing, while array CGH discovered a 70 kb microduplication encompassing KIAA2022 exon 1 in the third family. This duplication decreased KIAA2022 mRNA level in patients' lymphocytes by 60%. Detailed clinical examination of all patients, including the two initially reported, indicated moderate-to-severe ID with autistic features, strabismus in all patients, with no specific dysmorphic features other than a round face in infancy and no structural brain abnormalities on magnetic resonance imaging (MRI). Interestingly, the patient with decreased KIAA2022 expression had only mild ID with severe language delay and repetitive behaviors falling in the range of an autism spectrum disorder (ASD). Since little is known about KIAA2022 function, we conducted morphometric studies in cultured rat hippocampal neurons. We found that siRNA-mediated KIAA2022 knockdown resulted in marked impairment in neurite outgrowth including both the dendrites and the axons, suggesting a major role for KIAA2022 in neuron development and brain function.

The 2q37-deletion syndrome: an update of the clinical spectrum including overweight, brachydactyly and behavioural features in 14 new patients.

The 2q37 locus is one of the most commonly deleted subtelomeric regions. Such a deletion has been identified in >100 patients by telomeric fluorescence in situ hybridization (FISH) analysis and, less frequently, by array-based comparative genomic hybridization (array-CGH). A recognizable '2q37-deletion syndrome' or Albright's hereditary osteodystrophy-like syndrome has been previously described. To better map the deletion and further refine this deletional syndrome, we formed a collaboration with the Association of French Language Cytogeneticists to collect 14 new intellectually deficient patients with a distal or interstitial 2q37 deletion characterized by FISH and array-CGH. Patients exhibited facial dysmorphism (13/14) and brachydactyly (10/14), associated with behavioural problems, autism or autism spectrum disorders of varying severity and overweight or obesity. The deletions in these 14 new patients measured from 2.6 to 8.8 Mb. Although the major role of HDAC4 has been demonstrated, the phenotypic involvement of several other genes in the deleted regions is unknown. We further refined the genotype-phenotype correlation for the 2q37 deletion. To do this, we examined the smallest overlapping deleted region for candidate genes for skeletal malformations (facial dysmorphism and brachydactyly), overweight, behavioural problems and seizures, using clinical data, a review of the literature, and the Manteia database. Among the candidate genes identified, we focus on the roles of PRLH, PER2, TWIST2, CAPN10, KIF1A, FARP2, D2HGDH and PDCD1.

PRRT2 links infantile convulsions and paroxysmal dyskinesia with migraine.

OBJECTIVE: Whole genome sequencing and the screening of 103 families recently led us to identify PRRT2 (proline-rich-transmembrane protein) as the gene causing infantile convulsions (IC) with paroxysmal kinesigenic dyskinesia (PKD) (PKD/IC syndrome, formerly ICCA). There is interfamilial and intrafamilial variability and the patients may have IC or PKD. Association of IC with hemiplegic migraine (HM) has also been reported. In order to explore the mutational and clinical spectra, we analyzed 34 additional families with either typical PKD/IC or PKD/IC with migraine. METHODS: We performed Sanger sequencing of all PRRT2 coding exons and of exon-intron boundaries in the probands and in their relatives whenever appropriate. RESULTS: Two known and 2 novel PRRT2 mutations were detected in 18 families. The p.R217Pfs*8 recurrent mutation was found in ≈50% of typical PKD/IC, and the unreported p.R145Gfs*31 in one more typical family. PRRT2 mutations were also found in PKD/IC with migraine: p.R217Pfs*8 cosegregated with PKD associated with HM in one family, and was also detected in one IC patient having migraine with aura, in related PKD/IC familial patients having migraine without aura, and in one sporadic migraineur with abnormal MRI. Previously reported p.R240X was found in one patient with PKD with migraine without aura. The novel frameshift p.S248Afs*65 was identified in a PKD/IC family member with IC and migraine with aura. CONCLUSIONS: We extend the spectrum of PRRT2 mutations and phenotypes to HM and to other types of migraine in the context of PKD/IC, and emphasize the phenotypic pleiotropy seen in patients with PRRT2 mutations.

Bipolar affective disorder and early dementia onset in a male patient with SHANK3 deletion.

The SHANK3 protein is a scaffold protein known to stabilize metabotropic glutamate receptor mGluR5 in the post-synaptic membrane of neurons. It is associated with genetic vulnerability in autism and schizophrenia. Here we report the case of an 18 year-old male patient who displayed psychiatric features of bipolar affective disorder associated with early setting of dementia. This mental status is related to sporadic occurrence of SHANK3 gene complex multiple deletions. A low beta amyloid protein rate (479 mg/L) found in cerebrospinal fluid suggests a possible link between SHANK3 deletion syndrome-associated regression and dementia of Alzheimers's type. In addition, we propose an overview of the phenotype related to SHANK3 deletion.

Benign hereditary chorea: phenotype, prognosis, therapeutic outcome and long term follow-up in a large series with new mutations in the TITF1/NKX2-1 gene.

BACKGROUND: Benign hereditary chorea (BHC) is a rare autosomal dominant disorder characterised by childhood onset that tends to improve in adulthood. The associated gene, NKX2-1 (previously called TITF1), is essential for organogenesis of the basal ganglia, thyroid and lungs. The aim of the study was to refine the movement disorders phenotype. We also studied disease course and response to therapy in a large series of genetically proven patients. METHODS: We analysed clinical, genetic findings and follow-up data in 28 NKX2-1 mutated BHC patients from 13 families. RESULTS: All patients had private mutations, including seven new mutations, three previously reported mutations and three sporadic deletions encompassing the NKX2-1 gene. Hypotonia and chorea were present in early infancy, with delayed walking ability (25/28); dystonia, myoclonus and tics were often associated. Attention deficit hyperactivity disorder (ADHD) was present in seven. Among the 14 patients followed-up until adulthood, nine had persistent mild chorea, two had near total resolution of chorea but persistent disabling prominent myoclonus and three recovered completely. Learning difficulties were observed in 20/28 patients, and three had mental retardation. Various combinations of BHC, thyroid (67%) and lung (46%) features were noted. We found no genotype-phenotype correlation. A rapid and sustained beneficial effect on chorea was obtained in 5/8 patients treated with tetrabenazine. CONCLUSION: Early onset chorea preceded by hypotonia is suggestive of BHC. Associated thyroid or respiratory disorders further support the diagnosis and call for genetic studies. Tetrabenazine may be an interesting option to treat disabling chorea.

Epileptic encephalopathies of the Landau-Kleffner and continuous spike and waves during slow-wave sleep types: genomic dissection makes the link with autism.

PURPOSE: The continuous spike and waves during slow-wave sleep syndrome (CSWSS) and the Landau-Kleffner (LKS) syndrome are two rare epileptic encephalopathies sharing common clinical features including seizures and regression. Both CSWSS and LKS can be associated with the electroencephalography pattern of electrical status epilepticus during slow-wave sleep and are part of a clinical continuum that at its benign end also includes rolandic epilepsy (RE) with centrotemporal spikes. The CSWSS and LKS patients can also have behavioral manifestations that overlap the spectrum of autism disorders (ASD). An impairment of brain development and/or maturation with complex interplay between genetic predisposition and nongenetic factors has been suspected. A role for autoimmunity has been proposed but the pathophysiology of CSWSS and of LKS remains uncharacterized. METHODS: In recent years, the participation of rare genomic alterations in the susceptibility to epileptic and autistic disorders has been demonstrated. The involvement of copy number variations (CNVs) in 61 CSWSS and LKS patients was questioned using comparative genomic hybridization assays coupled with validation by quantitative polymerase chain reaction (PCR). KEY FINDINGS: Whereas the patients showed highly heterogeneous in genomic architecture, several potentially pathogenic alterations were detected. A large number of these corresponded to genomic regions or genes (ATP13A4, CDH9, CDH13, CNTNAP2, CTNNA3, DIAPH3, GRIN2A, MDGA2, SHANK3) that have been either associated with ASD for most of them, or involved in speech or language impairment, or in RE. Particularly, CNVs encoding cell adhesion proteins (cadherins, protocadherins, contactins, catenins) were detected with high frequency (≈20% of the patients) and significant enrichment (cell adhesion: p = 0.027; cell adhesion molecule binding: p = 9.27 × 10(-7)). SIGNIFICANCE: Overall our data bring the first insights into the possible molecular pathophysiology of CSWSS and LKS. The overrepresentation of cell adhesion genes and the strong overlap with the genetic, genomic and molecular ASD networks, provide an exciting and unifying view on the clinical links among CSWSS, LKS, and ASD.

Microtriplication of 11q24.1: a highly recognisable phenotype with short stature, distinctive facial features, keratoconus, overweight, and intellectual disability.

BACKGROUND: Partial tetrasomy is mainly described as a cytogenetically visible rearrangement due to a supernumerary chromosome (i(12p), i(18p), inv dup(15)). Except for chromosome 15q11q13, intrachromosomal triplications are rare and so far not associated with a recognisable phenotype. METHODS AND RESULTS: This report describes two unrelated patients with a de novo non-recurrent submicroscopic interstitial triplication 11q24.1 detected with array comparative genomic hybridisation and confirmed by fluorescence in situ hybridisation, molecular combing, and quantitative PCR. Microsatellite analysis suggested that a common mechanism of rearrangement might have been involved. These patients share remarkably similar clinical features including distinctive facial dysmorphisms, short stature with small extremities, keratoconus, overweight, and intellectual disability. The overlapping region of 1.8 Mb contains 11 RefSeq genes and three microRNA related genes. Interestingly, the overexpression of ASAM, a gene encoding an adipocyte specific adhesion molecule, may contribute to patients' obesity. Upregulation of BILD, known to mediate apoptosis in a caspase dependent manner, could deserve further investigation into the pathological mechanism of keratoconus. CONCLUSION: Isolated duplications of distal 11q region have been previously reported and associated with intellectual disability but without a consistent set of clinical features. These findings support the proposal that microtriplication 11q24.1 is a well recognisable clinical entity.

Idiopathic hypersomnia: a report of three adolescent-onset cases in a two-generation family.

Idiopathic hypersomnia is an uncommon sleep disorder characterized by prolonged sleep time and excessive daytime sleepiness without cataplexy. This study concerned a case of familial occurrence. The proband expressed an idiopathic hypersomnia with long sleep time at the age of 12 years. Clinical interview and ad libitum polysomnographic study did not reveal any symptoms of narcolepsy or other sleep disorders. Family history revealed that a 20-year-old sister had experienced symptoms of hypersomnia from the age of 16 and their mother had been diagnosed with idiopathic hypersomnia previously. The diagnosis of idiopathic hypersomnia with long sleep time was confirmed in the sister by clinical interview and ad libitum polysomnography. Human leukocyte antigen (HLA) did not reveal the DQB1-0602 phenotype in the proband and relatives. This report confirms the hypothesis of a genetic predisposition in idiopathic hypersomnia.

Novel familial cases of ICCA (infantile convulsions with paroxysmal choreoathetosis) syndrome.

Epilepsy and paroxysmal dyskinesia are two episodic cerebral disorders that can share a common genetic basis. Rare families with infantile seizures and paroxysmal dyskinesia [predominantly paroxysmal kinesigenic dyskinesia (PKD)], co-inherited as a single autosomal dominant trait, have been described (infantile convulsions with paroxysmal choreoathetosis; ICCA syndrome) and a disease gene has been mapped at chromosome 16p12-q12 (ICCA region). We report the clinical picture of seven previously unreported families with ICCA syndrome. The identification of novel ICCA families should contribute to better knowledge regarding the clinical manifestations of ICCA syndrome as well as the search for the underlying genetic defect(s).

Speech disturbances in patients with dystonia or chorea due to neurometabolic disorders.

Speech disturbances are frequent and potentially disabling in patients with dystonia or chorea due to neurometabolic disorders (DCND), but their precise characteristics are poorly documented. We prospectively studied 29 consecutive patients with DCND. A detailed description of their speech patterns was obtained by using the Frenchay dysarthria assessment test and the apraxia of speech evaluation test of Wertz. Gross motor function and intelligibility were each scored on 5-point scales to identify a possible correlation between the severity of the speech and motor disorders. All the patients were found to have complex speech alterations with combined features of hyperkinetic dysarthria and speech apraxia. We also noted a correlation between the severity of the speech disorders and the motor disorders. These findings have important implications for speech rehabilitation, and may provide new insights into the pathophysiology of dystonia due to neurometabolic disorders.

Mutational, functional, and expression studies of the TCF4 gene in Pitt-Hopkins syndrome.

Pitt-Hopkins syndrome is a severe congenital encephalopathy recently ascribed to de novo heterozygous TCF4 gene mutations. We report a series of 13 novel PHS cases with a TCF4 mutation and show that EEG, brain magnetic resonance imagain (MRI), and immunological investigations provide valuable additional clues to the diagnosis. We confirm a mutational hot spot in the basic domain of the E-protein. Functional studies illustrate that heterodimerisation of mutant TCF4 proteins with a tissue-specific transcription factor is less effective than that homodimerisation in a luciferase reporter assay. We also show that the TCF4 expression pattern in human embryonic development is widespread but not ubiquitous. In summary, we further delineate an underdiagnosed mental retardation syndrome, highlighting TCF4 function during development and facilitating diagnosis within the first year of life.

Spectrum of movement disorders associated with glutaric aciduria type 1: a study of 16 patients.

Glutaric aciduria type 1 (GA1) is an autosomal recessive neurometabolic disorder due to glutaryl CoA dehydrogenase deficiency. Comprehensive descriptions of GA1-associated movement disorders are rare. In order to refine the description of the motor phenotype, we prospectively studied 16 consecutive pediatric and adult GA1 patients, focusing on the movement disorders and their time course. In most patients, generalized dystonia, superimposed on baseline axial hypotonia, remained the predominant feature throughout the disease course. With aging, it tended to evolve from mobile to fixed dystonia and to be associated with akinetic-rigid parkinsonism. Prominent orofacial involvement was a consistent feature in GA1 patients with movement disorders, resulting in speech disorders with features of combined hyperkinetic dysarthria and speech apraxia. The types and outcome of movement disorders in this setting should be taken into consideration during rehabilitation and for patient selection and evaluation in therapeutic trials.