Using medical exome sequencing to identify the causes of neurodevelopmental disorders: Experience of 2 clinical units and 216 patients.

Although whole-exome sequencing (WES) is the gold standard for the diagnosis of neurodevelopmental disorders (NDDs), it remains expensive for some genetic centers. Commercialized panels comprising all OMIM-referenced genes called "medical exome" (ME) constitute an alternative strategy to WES, but its efficiency is poorly known. In this study, we report the experience of 2 clinical genetic centers using ME for diagnosis of NDDs. We recruited 216 consecutive index patients with NDDs in 2 French genetic centers, corresponded to the daily practice of the units and included non-syndromic intellectual disability (NSID, n = 33), syndromic ID (NSID = 122), pediatric neurodegenerative disorders (n = 7) and autism spectrum disorder (ASD, n = 54). We sequenced samples from probands and their parents (when available) with the Illumina TruSight One sequencing kit. We found pathogenic or likely pathogenic variants in 56 index patients, for a global diagnostic yield of 25.9%. The diagnosis yield was higher in patients with ID as the main diagnosis (32%) than in patients with ASD (3.7%). Our results suggest that the use of ME is a valuable strategy for patients with ID when WES cannot be used as a routine diagnosis tool.

Monoamine neurotransmitters and movement disorders in children and adults.

Neurotransmitter disorders comprise a rapidly expanding phenotypically and genetically heterogeneous group. Most of these disorders start in infancy through to childhood, although some forms may arise in adolescence and adulthood, and have various presentations. They may be overlooked if the phenotype leads to misdiagnoses involving various combinations of developmental disorders, hypotonia and movement disorders (dystonia, hyperkinesia, parkinsonism) or other clinical manifestations, such as sleep alterations and mood disorders. Neurotransmitter metabolite levels in cerebrospinal fluid (CSF) may help us to analyze and better understand the metabolic cascade and changes in dopamine and serotonin synthesis, and also guide genetic testing. Indeed, it is important to recognize these disorders in their early stages as they can be greatly improved by drug treatments, and if clinical responses are insufficient, then other agents that may enhance neurotransmission, such as serotonergic drugs and tetrahydrobiopterin (BH4) supplementation, could be considered. Also, a precise genetic diagnosis should be established by gene panels for dystonia, SNP microarrays and whole-exome sequencing. The present brief survey aims to review the present state of the art for the most commonly described and rare disorders of dopamine and serotonin, as well as cofactor deficiencies and dysfunctions, with an overview of clinical features, diagnostic strategies and treatments. Moreover, although these are mainly disorders of infants and children, many may nevertheless reach adulthood; thus, their evolution and treatments should be well known not only by pediatricians, but by neurologists as well, as the latter may be in charge at the stage of diagnosis (rarely) and during the follow-up of these rare patients.

Inverted duplication with deletion: first interstitial case suggesting a novel undescribed mechanism of formation.

Inverted duplications with terminal deletions are a well-defined family of complex rearrangements already observed for most of chromosome extremities. Several mechanisms have been suggested which could lead to their occurrence, either through non-homologous end joining, non-allelic homologous recombination, or more recently through an intrastrand fold-back mechanism. We describe here a patient with intellectual disability and pharmacoresistant epilepsy, for which array CGH analysis showed the first interstitial case of inverted duplication with deletion on chromosome 1p. Furthermore, SNP array analysis revealed an associated segmental isodisomy for the distal part of 1p, which led us to consider a replicative mechanism to explain this abnormality. This observation extends the range of this once telomeric rearrangement.

GLUT1 deficiency syndrome: an update.

INTRODUCTION: Glucose transporter type 1 deficiency syndrome is caused by heterozygous, mostly de novo, mutations in the SLC2A1 gene encoding the glucose transporter GLUT1. Mutations in this gene limit brain glucose availability and lead to cerebral energy deficiency. STATE OF THE ART: The phenotype is characterized by the variable association of mental retardation, acquired microcephaly, complex motor disorders, and paroxysmal manifestations including seizures and non-epileptic paroxysmal episodes. Clinical severity varies from mild motor dysfunction to severe neurological disability. In patients with mild phenotypes, paroxysmal manifestations may be the sole manifestations of the disease. In particular, the diagnosis should be considered in patients with paroxysmal exercise-induced dyskinesia or with early-onset generalized epilepsy. Low CSF level of glucose, relative to blood level, is the best biochemical clue to the diagnosis although not constantly found. Molecular analysis of the SLC2A1 gene confirms the diagnosis. Ketogenic diet is the cornerstone of the treatment and implicates a close monitoring by a multidisciplinary team including trained dieticians. Non-specific drugs may be used as add-on symptomatic treatments but their effects are often disappointing. CONCLUSION: Glucose transporter type 1 deficiency syndrome is likely under diagnosed due to its complex and pleiotropic phenotype. Proper identification of the affected patients is important for clinical practice since the disease is treatable.

Treatment for dystonia in childhood.

Management of childhood dystonia differs in certain respects from that of adult dystonia: (i) childhood dystonia is more often secondary than primary; (ii) mixed motor disorders are frequent; (iii) in children, the course of dystonia may be influenced by ongoing brain maturation and by the remarkable plasticity of the young brain; (iv) drug tolerability and effectiveness can be different in children; (v) the therapeutic strategy must be discussed with both the patient and his or her parents; and (vi) the child's education must be taken into account. Based on a systematic review of the literature through June 2011 and on our personal experience, we propose a therapeutic approach to childhood dystonia. After a detailed clinical evaluation and a comprehensive work-up to rule out a treatable cause of dystonia, symptomatic treatment may include various drugs, local botulinum toxin injections, and deep brain stimulation, in addition to rehabilitation.

Enlargement of the Optic Chiasm: A Novel Imaging Finding in Glutaric Aciduria Type 1.

Patients with glutaric aciduria type 1, without early diagnosis and initiation of preventive treatment, often develop movement disorders and various degrees of motor disability due to striatal area-specific damage induced by an acute episode of metabolic decompensation. The neuroimaging phenotype of patients with glutaric aciduria type 1 includes characteristic cyst-like bilateral enlargement of the Sylvian fissures and anterior subarachnoid spaces and signal abnormalities including supratentorial white matter and deep gray matter structure T2 hyperintensities, frequently associated with restricted diffusion. In this retrospective study, we add to the neuroimaging spectrum of glutaric aciduria type 1, a novel imaging finding present regardless of a previous metabolic crisis: the enlargement of the optic chiasm associated with signal abnormalities in the anterior intracranial visual structures observed in 6 of 10 patients. These optic pathway abnormalities are suggested as useful diagnostic clues for glutaric aciduria type 1, and possible pathophysiologic mechanisms are discussed.

[Paroxysmal kinesigenic dyskinesia: a channelopathy? Study of 19 cases]. / Les dyskinésies paroxystiques kinésigéniques : une << canalopathie >> ? Etude de 19 cas.

INTRODUCTION: Paroxysmal kinesigenic dyskinesia (PKD) is characterized by brief episodes of dystonia and choreoathetosis triggered by sudden voluntary movements. Disease onset is seen in the first or second decade. The attacks typically last less than one minute. Three autosomal dominant PKD loci are identified: EKD1, EKD2 and EKD3. EKD1 has an overlap with the locus of the "Infantile Convulsion and Choreoathetosis (ICCA) syndrome". The favorable natural history, the episodic nature of the symptoms and their sensitivity to anticonvulsant therapy suggest channelopathy as a mechanism of PKD. PATIENTS AND METHODS: We reviewed the clinical features, the family history, the treatment response, the evolution and the technical investigations in 19 affected individuals. RESULTS: All cases were idiopathic. Ten patients had a positive familial history. Three patients suffered from ICCA syndrome. Some atypical features were seen, such as the association of kinesigenic and nonkinesigenic attacks and the presence of migraine, ataxia, seizures and myoclonus. Acetazolamide responsiveness was seen in two patients. CONCLUSION: The coexistence of PKD and nonkinesigenic dyskinesia in several patients confirms the earlier described presence of intermediary forms, nonrepresented in the current classification of paroxysmal dyskinesias. Our study results suggest channel dysfunction and basal ganglia involvement in the pathophysiology of PKD.

Epsilon sarcoglycan mutations and phenotype in French patients with myoclonic syndromes.

BACKGROUND: Myoclonus dystonia syndrome (MDS) is an autosomal dominant movement disorder caused by mutations in the epsilon-sarcoglycan gene (SGCE) on chromosome 7q21. METHODS: We have screened for SGCE mutations in index cases from 76 French patients with myoclonic syndromes, including myoclonus dystonia (M-D), essential myoclonus (E-M), primary myoclonic dystonia, generalised dystonia, dystonia with tremor, and benign hereditary chorea. All coding exons of the SGCE gene were analysed. The DYT1 mutation was also tested. RESULTS: Sixteen index cases had SGCE mutations while one case with primary myoclonic dystonia carried the DYT1 mutation. Thirteen different mutations were found: three nonsense mutations, three missense mutations, three splice site mutations, three deletions, and one insertion. Eleven of the SGCE index cases had M-D and five E-M. No SGCE mutations were detected in patients with other phenotypes. The total number of mutation carriers in the families was 38, six of whom were asymptomatic. Penetrance was complete in paternal transmissions and null in maternal transmissions. MDS patients with SGCE mutation had a significantly earlier onset than the non-carriers. None of the patients had severe psychiatric disorders. CONCLUSION: This large cohort of index patients shows that SGCE mutations are primarily found in patients with M-D and to a lesser extent E-M, but are present in only 30% of these patients combined (M-D and E-M).

Anti-flatulence treatment and status epilepticus: a case of camphor intoxication.

We describe a case of a young child who lived in Hong Kong who presented with a severe epilepticus status after a return flight to Paris. Routine laboratory tests failed to establish a cause. Upon further questioning, the parents reported that the nanny had given an abdominal massage to the child with an unlabelled solution reported to have anti-flatulence effects. Toxicological analysis of this solution revealed the presence of camphor. Although the highly toxic effects of camphor have long been established, the present case illustrates that camphor continues to be a source of paediatric exposure. This case highlights the importance of systematic questioning and recalls the extreme danger associated with camphor even when administered transcutaneously.

[Human herpes virus type 6, etiology of an acute encephalitis in childhood: case report]. / L'HHV-6, une cause de leucoencéphalite aiguë disséminée du nourrisson: à propos de 1 observation.

Primary infection with human herpesvirus-6 (HHV-6) causes the classical roseola infantum. Otherwise the infection is clinically silent but it may sometimes be responsible for central nervous system involvement. In order to illustrate such a type of lesions, we report on a 16-month-old girl with acute leucoencephalitis. The disease started with pyrexia 40 degrees C, followed by an episode of seizure, erythematous rash on the trunk and then coma. Brain MRI showed wide lesions on white matter. HHV-6 DNA was detected by PCR in the CSF and serum at the acute stage, and tests for HHV-6 antibody showed a significant increase of IgG antibody titre between acute and convalescent sera. One month later complete clinical recovery was observed while the MRI showed a partial disappearance of the lesions. The sero-conversion associated with the detection of the viral DNA in the serum identified a primary HHV-6 infection and the detection of viral nucleic acid in CSF gives arguments for the responsibility of the virus in the pathogenesis. When facing an acute leuco-encephalitis in infants, it is important to perform exhaustive virology investigations to rule out the implication of HHV-6 as well as other commonly incriminated pathogens (EBV, CMV, mycoplasma, enterovirus) to avoid accusing wrongly the vaccines.

[Dystonia 12: A rare and difficult diagnosis]. / Dystonie de type 12 : un diagnostic rare et difficile.

We report a case of dystonia 12, also called rapid-onset dystonia-parkinsonism, which occurred in a young 12-year-old boy. Type 12 dystonia is a genetic syndrome characterized by a pathogenic mutation on ATP1A3 gene encoding the subunit alpha 3 of Na-K-ATPase protein, resulting in neuronal dysfunctions. It remains a rare syndrome with less than 100 cases described in the literature. Its atypical presentation and its rarity may lead to a wandering diagnosis, even in some cases to a conversion hysteria diagnosis. Today, unfortunately, there is no effective treatment.

Advances in the metabolic profiling of acidic compounds in children's urines achieved by comprehensive two-dimensional gas chromatography.

The main objective of this work was to evaluate a comprehensive two-dimensional gas chromatographic (GCxGC) coupled to quadrupole mass spectrometry (qMS) method in the field of biomarker candidates' discovery. To this purpose we developed a GCxGC-qMS method suitable for the separation of organic acids and other classes of compounds with silylable polar hydrogen such as sugars, amino-acids, and vitamins. As compared to those obtained by a widely used 1D-GC method, the urinary chromatographic profiles performed by the proposed 2D-GC method exhibit higher resolution and sensitivity, leading to the detection of up to 92 additional compounds in some urine samples including some well-known biomarkers. In order to validate the proposed method we focused on three metabolites of interest with various functional groups and polarities including CH3-malonic acid (MMA: biomarker of methylmalonic acidemia), 3-hydroxy-3-methyl-glutaric acid (3-OHMGA: biomarker of 3-hydroxy-3-methylglutaric acidemia), and phenylpiruvic acid (PhPA: marker of phenylketonuria). While these three metabolites can be considered as representative of organic acids classically determined by 1D-GC, they cannot be representative of new detected metabolites. Thus, we also focused on quinolic acid (QUIN), taken as an example of biomarker not detected at basal levels with the classical 1D GC-qMS method. In order to obtain sufficient recoveries for all tested compounds, we developed a sample preparation protocol including a step of urea removal followed by two extraction steps using two solvents of different polarity and selectivity. Recoveries with the proposed method reached more than 80% for all targeted compounds and the linearity was satisfactory up to 50µmol/L. The CVs of the within-run and within-laboratory precisions were less than 8% for all tested compounds. The limits of quantification (LOQs) were 0.6µmol/L for MMA, 0.4µmol/L for 3-OHMGA, 0.7µmol/L for PhPA, and 1µmol/L for QUIN. The LOQs of these metabolites obtained by a classical GC-MS method under the same chromatographic conditions were 5µmol/L for MMA, 4µmol/L for 3-OHMGA, 6µmol/L for PhPA while QUIN was below the limit of detection. As compared to 1D-GC, these results highlight the enhanced detectability of urine metabolites by the 2D-GC technique. Our results also show that for each new detected compound it is necessary to develop and validate an appropriate sample preparation procedure.

[Study of visual field and vigabatrin treatment in children]. / Etude du champ visuel et traitement par vigabatrin chez l'enfant.

INTRODUCTION: Concentric visual field defects have been described in association with vigabatrin, a GABA mimetic antiepileptic agent. Few cases have been reported in children. METHODS: A systematic ophthalmological examination was performed in 14 children treated with vigabatrin for seizures. A manual kinetic perimetry test (Goldmann) was done in 11 cases. The ERG was recorded in the 3 cases where perimetry could not be done. RESULTS: All children were asymptomatic. The mean age was 9.6 years. The mean duration of vigabatrin treatment was 41 months. The visual field was abnormal when central and peripheral fields were constricted. A visual field defect was discovered in 6 cases: 4 were severe, 2 were mild. When vigabatrin treatment was stopped, 1 case became worse, 1 case was slightly better, and 1 case remained stationary. A disturbed ERG was found in 3 children (depressed b-wave, raised a/b ratio). CONCLUSION: The visual field defects discovered in children treated with vigabatrin are similar to those described in adults. The incidence and progression of visual field constriction in children with and after vigabatrin treatment are not yet well known. Children treated with vigabatrin should therefore have systematic and regular ophthalmological perimetry, and ERG examinations.

[Spasmus nutans: apropos of 16 cases]. / Spasmus nutans: à propos de 16 cas.

UNLABELLED: Spasmus nutans is a syndrome occurring in early childhood. It consists of a triad of symptoms: head nodding, ocular oscillations and anomalous head position. Ophthalmologic and neurological findings are otherwise normal. This syndrome is benign and has spontaneous resolution. PATIENTS AND METHOD: Sixteen patients with spasmus nutans seen from 1980 to 1995 were retrospectively studied. Their present status was evaluated by clinical examination or questionnaire. RESULTS: The age at onset ranged from 1 to 15 months (average 7 months). Thirteen of 16 patients were referred for head nodding, which was a constant manifestation; its direction was horizontal, vertical or rotatory. Nystagmus was present in 14 infants. It was acquired, asymmetrical, bilateral (or unilateral in three cases), rapid, fine, pendular and horizontal. Both head nodding and nystagmus were intermittent. Anomalous head position was present in seven cases, consisting of head tilt or a chin upon/chin down posture. Neuroimaging (13 cases) was always normal. The follow-up in 12 children (up to 2 years) showed a complete resolution of the syndrome in 6 months to 6 years (average 2.5 years). DISCUSSION: The diagnosis was established by the constancy of the characteristic triad and the elimination of the other causes of nystagmus. Isolated head nodding had to be distinguished from bobble head syndrome. In several reported cases, electronystagmography recordings have suggested that head nodding is a compensatory process against nystagmus and that the head tilt allows transient resolution of the nystagmus. CONCLUSION: Spasmus nutans is a self-limiting benign clinical entity. Normal complete ophthalmologic and neurological examination, as well as magnetic resonance imaging (MRI) are necessary to confirm the diagnosis.

[Acute optic neuritis in children: clinical features and treatment. A study of 28 eyes in 20 children]. / Les neuropathies optiques aiguës de l'enfant: particularités cliniques et thérapeutiques. A propos de 28 yeux chez 20 enfants.

PURPOSE: Analyzing a personal series of children with acute optic neuritis (AON), we studied MATERIAL AND METHODS: A retrospective study of 28 eyes in 20 patients (mean age: 10;7 years), examined between 1982 and 1997, with a follow-up ranging from 6 months to 15 years (mean: 5;5 years). We recorded etiologic factors, clinical features (ocular and extra ocular), biological results, and neuroimaging findings. RESULTS: Initial involvement was uni- or bilateral with poor visual acuity (under 20/200 in 22 eyes of 28). Intracerebral inflammation was present in 9 of 13 cases where MRI was performed. We found a cause in only 7 cases (5 viral diseases and 2 recent vaccinations against hepatitis B). Visual recovery was good (over 20/25 in 20 eyes of 28) whatever the treatment, but AON recurred in 5 children. Four children later developed multiple sclerosis. CONCLUSIONS: The cause of AON is rarely found. After eliminating an infection, we retained viral disease, complication of a recent vaccination against hepatitis B, and neurological diseases. MRI was the imaging study of choice. Development of multiple sclerosis occurred in 4 cases of 20, the same frequency as in the literature. The risk of later development of multiple sclerosis was 20%. Progression of AON was often excellent. Nevertheless, corticotherapy was added, in form of intravenous boluses followed by decreasing oral therapy for one month.

[Management of acute visual loss in children]. / Conduite à tenir devant une baisse aiguë de l'acuité visuelle chez l'enfant.

Acute or rapidly progressive visual loss in children needs urgent attention and treatment. It may be unilateral orbilateral. Etiology depends upon the involved areas: eye ball, optic nerve, retro-chiasmatic pathways. Psychogenic origin is quite common in school-age children, however, it has to be considered last. Unilateral visual loss may be overlooked. Acute total transitory visual loss may be due to epilepsy or to migraine. Rapidly progressive visual loss may be due to retinal disease, optic neuritis or cortical blindness. Management of visual loss depends on clinical features, associated symptoms, and aspect of the optic disc. It needs collaboration between ophthalmologist,pediatrician and neuropediatrician. Retinal hemorrhages first call to mind a traumatic origin. Swelling of the optic disc may be due to increased intracranial pressure or due to optic neuritis. When the optic disc is normal it is necessary to rule out organic diseases before establishing the diagnosis of a psychogenic vision disturbance. In emergency, brain neuroimaging is the best way to diagnose intracranial mass and visualize optic pathways.

["Idiopathic" acute optic neuropathies in children]. / Les neuropathies optiques aiguës "idiopathiques" de l'enfant.

We reported a retrospective study of 27 children (mean age = 10 years), who presented a loss of vision due to an acute optic neuritis, between 1982 and 1997. The symptoms ar more likely bilateral in children, and frequently associated with systemic viral infection or hepatitis B vaccination. Multiple sclerosis occurs approximately in 20 p. cent of the cases, i.e. less frequently than by adults. Magnetic resonance imaging is now systematic: in 20 children hyperintense nodular abnormalities in a various distribution was demonstrated by 9 children. During the follow-up, 23 eyes of 27 have an excellent recovery of vision, but 4 patients have developed multiple sclerosis. Corticotherapy was uses in 23 cases, in the form of methylprednisolone intravenous flashes in 14 cases.

[Treatment of childhood dystonia]. / Traitement des dystonies de l'enfant.

Dystonia is not uncommon in childhood, but is clinically very heterogeneous. Therefore, introduction and follow-up of the treatment of dystonia in children are often a challenge for the physicians. Progresses in functional neurosurgery have open new fields in the treatment of dystonia in children, but it should be managed by a multidisciplinary team. This paper reviews the various therapeutic options available for childhood-onset dystonia, with a specific attention to dosage and side effects of the drugs regarding pediatric population according to the data of the literature. The rational strategy for therapeutic management of the various types of childhood dystonia is discussed.