Phenotype and genotype in 101 males with X-linked creatine transporter deficiency.

BACKGROUND: Creatine transporter deficiency is a monogenic cause of X-linked intellectual disability. Since its first description in 2001 several case reports have been published but an overview of phenotype, genotype and phenotype--genotype correlation has been lacking. METHODS: We performed a retrospective study of clinical, biochemical and molecular genetic data of 101 males with X-linked creatine transporter deficiency from 85 families with a pathogenic mutation in the creatine transporter gene (SLC6A8). RESULTS AND CONCLUSIONS: Most patients developed moderate to severe intellectual disability; mild intellectual disability was rare in adult patients. Speech language development was especially delayed but almost a third of the patients were able to speak in sentences. Besides behavioural problems and seizures, mild to moderate motor dysfunction, including extrapyramidal movement abnormalities, and gastrointestinal problems were frequent clinical features. Urinary creatine to creatinine ratio proved to be a reliable screening method besides MR spectroscopy, molecular genetic testing and creatine uptake studies, allowing definition of diagnostic guidelines. A third of patients had a de novo mutation in the SLC6A8 gene. Mothers with an affected son with a de novo mutation should be counselled about a recurrence risk in further pregnancies due to the possibility of low level somatic or germline mosaicism. Missense mutations with residual activity might be associated with a milder phenotype and large deletions extending beyond the 3' end of the SLC6A8 gene with a more severe phenotype. Evaluation of the biochemical phenotype revealed unexpected high creatine levels in cerebrospinal fluid suggesting that the brain is able to synthesise creatine and that the cerebral creatine deficiency is caused by a defect in the reuptake of creatine within the neurones.

Refinement of cortical dysgeneses spectrum associated with TUBA1A mutations.

OBJECTIVE: We have recently shown that de novo mutations in the TUBA1A gene are responsible for a wide spectrum of neuronal migration disorders. To better define the range of these abnormalities, we searched for additional mutations in a cohort of 100 patients with lissencephaly spectrum for whom no mutation was identified in DCX, LIS1 and ARX genes and compared these data to five previously described patients with TUBA1A mutations. RESULTS: We detected de novo TUBA1A mutations in six patients and highlight the existence of a prominent form of TUBA1A related lissencephaly. In four patients, the mutations identified, c.1190T>C (p.L397P), c.1265G>A (p.R422H), c.1264C>T (p.R422C), c.1306G>T (p.G436R), have not been reported before and in two others, the mutation corresponds to a recurrent missense mutation, c.790C>T (p.R264C), likely to be a hot spot of mutation. All together, it emerges that the TUBA1A related lissencephaly spectrum ranges from perisylvian pachygyria, in the less severe form, to posteriorly predominant pachygyria in the most severe, associated with dysgenesis of the anterior limb of the internal capsule and mild to severe cerebellar hypoplasia. When compared with a large series of lissencephaly of other origins (ILS17, ILSX or unknown origin), these features appear to be specific to TUBA1A related lissencephaly. In addition, TUBA1A mutated patients share a common clinical phenotype that consists of congenital microcephaly, mental retardation and diplegia/tetraplegia. CONCLUSIONS: Our data highlight the presence of consistent and specific abnormalities that should allow the differentiation of TUBA1A related lissencephalies from those related to LIS1, DCX and ARX genes.

[Neurological aspects of Fabry's disease]. / Manifestations neurologiques de la maladie de Fabry.

Fabry disease is a rare X-linked disorder caused by deficient activity of the lysosomal enzyme alpha-galactosidase A. Progressive accumulation in lysosomes of the undegraded glycosphingolipids leads to a multi-system disease with dermatological, ocular, renal, cardiac, and neurological manifestations. Peripheral nerve involvement, neuropathic pain and chronic acroparesthesiae, are frequent and early-onset signs revealing the disease. They are due to the involvement of small nerve fiber, thus explaining the normality of electroneuromyography. Cochleo-vestibular and autonomic nervous system involvement is frequent. Besides rare aseptic meningitis, central nervous system involvement is essentially represented by cerebrovascular events (stroke, transient ischemic attack). Affecting essentially the posterior circulation, their etiologies have to be clarified: progressive stenosis of small vessels with globotriasocylceramide deposits, arterial remodeling, endothelial dysfunction, pro-thrombotic state, cerebral hypoperfusion consecutive to dysautonaumy, cardiac embolism. MRI shows numerous silent lesions, increasing with age, mainly in small perforant arteries (periventricular white matter, brainstem, cerebellum, basal ganglia). Pulvinar calcifications, due to an increase in cerebral hyperperfusion, could be specific of Fabry disease. Positon tomography analysis shows a reduced cerebral flow velocity and impaired cerebral autoregulation, secondary to the glycosphingolipid storage in vascular endothelial cells. Enzyme replacement therapy has to be carefully monitored.

Diffuse cortical dysplasia, or the 'double cortex' syndrome: the clinical and epileptic spectrum in 10 patients.

Diffuse neuronal migration disorders associated with epilepsy can now be recognized by modern neuroimaging techniques, particularly high-resolution MRI. We report 10 patients with a recently described MRI picture of continuous or generalized band heterotopia underlying the cortical mantle, giving the appearance of a "double cortex." They have epilepsy, and almost all have mental retardation. The epileptic disorder varies in nature and degree of severity. Patients may present with infantile spasms, a Lennox-Gastaut syndrome, or other forms of secondary generalized or multifocal epilepsy. Response to medical treatment is variable. Callosotomy may lead to considerable reduction of drop attacks, present in 60%. Mental retardation is usually mild or moderate, and only rarely severe. It correlates with the type of epileptic syndrome, and is greater in patients with more disorganized cortex overlying the heterotopia. Recognition of this entity by MRI is important for appropriate diagnosis of the epileptic disorder, planning of therapeutic strategy, and prognosis.

X-linked malformations of neuronal migration.

Malformations of neuronal migration such as lissencephaly (agyria-pachygyria spectrum) are well-known causes of mental retardation and epilepsy that are often genetic. For example, isolated lissencephaly sequence and Miller-Dieker syndrome are caused by deletions involving a lissencephaly gene in chromosome 17p13.3, while many other malformation syndromes have autosomal recessive inheritance. In this paper, we review evidence supporting the existence of two distinct X-linked malformations of neuronal migration. X-linked lissencephaly and subcortical band heterotopia (XLIS) presents with sporadic or familial mental retardation and epilepsy. The brain malformation varies from classical lissencephaly, which is observed in males, to subcortical band heterotopia, which is observed primarily in females. The XLIS gene is located in chromosome Xq22.3 based on the breakpoint of an X-autosomal translocation. Bilateral periventricular nodular heterotopia (BPNH) usually presents with sporadic or familial epilepsy with normal intelligence, primarily in females, although we have evaluated two boys with BPNH and severe mental retardation. The gene for BPNH has been mapped to chromosome Xq28 based on linkage studies in multiplex families and observation of a subtle structural abnormality in one of the boys with BPNH and severe mental retardation.

Sleep disorders caused by brainstem tumor: case report.

Few studies concerning sleep disorders in brainstem lesions or tumors have been published. We report the case of a girl who was operated on for a brainstem tumor at the age of 4 years. In postsurgery, she had hemiparesis of the left side, swallowing difficulties, and severe apneas requiring a tracheotomy with nocturnal ventilation. The child's health improved progressively. Two sleep recordings were performed at 7 and 9 years without nocturnal ventilation. These recordings showed sleep disorders with a decrease in total sleep time and rapid eye movement (REM) sleep. Several central apneas were observed. The apneas were more frequent during REM sleep in the first recording and were associated with desaturation and microarousals.

Hot water epilepsy: a benign and unrecognized form.

Hot water epilepsy is a reflex epilepsy. Seizures are provoked by hot water, and result from the association of both cutaneous and heat stimuli. Described mainly in India and Japan, the condition seems to be rare in Europe, where it occurs in young children. We report five infants aged from 6 months to 2 years. They had brief seizures during bathing with activity arrest, hypotonia, and vasoactive modification; clonic movements were observed. A simple treatment-decreasing the bath temperature-can be sufficient. Sometimes an antiepileptic drug is required. Seizure course and psychomotor development are favorable. Hot water epilepsy is a benign form of epilepsy. Its incidence could be underestimated because of confusion with febrile convulsions, vagal fits, or aquagenic urticaria.

So-called 'cryptogenic' partial seizures resulting from a subtle cortical dysgenesis due to a doublecortin gene mutation.

We report the case of a female suffering from resistant partial seizures, which were related to 'cryptogenic' epilepsy, as the cerebral cortex was considered normal on the initial MRI images. As her son is mentally retarded and has a pachygyria, the doublecortin gene, usually involved in band heterotopia or lissencephaly, was screened for mutations. A missense mutation was identified, shared by both the son and his mother, and a subtle discontinuous subcortical heterotopia was subsequently detected on the mother's MRI. The pathophysiology of epilepsy in this woman is discussed in the light of the role of doublecortin, not only in neuronal migration, but also in axonal growth and dendritic connectivity.

[Subcortical laminal heterotopia and lissencephaly: cerebral malformations of X-linked inheritance]. / Hétérotopies laminaires sous-corticales et lissencéphalie: malformations cérébrales d'origine familiale commune, liée à l'X.

Subcortical laminar heterotopia (band heterotopia) is a brain malformation now recognized by MRI. We report 3 families (2 previously described) in which several members had subcortical laminar heterotopia or a more severe malformation (agyria/pachygyria). In these families, subcortical laminar heterotopia were observed in women and were associated with epilepsy or slight mental retardation depending on the extend of heterotopia. Males had lissencephaly with refractory epilepsy and severe mental retardation. The pedigrees of these families demonstrate that these 2 malformations originate from a single genetic origin. A single X-linked dominant gene is postulated. Diagnosis of subcortical laminar heterotopia in a female or lissencephaly in a male (except in the case of Miller-Dieker syndrome) requires appropriate genetic counselling in the family: brain imaging should be performed in relatives.

[GM2-Gangliosidosis variant B1 disclosed during adolescence by an isolated multi-systemic involvement of the central and peripheral nervous systems]. / Gangliosidose à GM2 variant B1. Révélation à l'adolescence par une atteinte isolée et plurisystématisée du système nerveux central et périphérique.

The authors report on a Portuguese family with 3 adult brothers affected with GM2-gangliosidosis (B1 variant) in a sibship of 4, and more specifically on one of these brothers with neurological onset at the age of 17. Psychosis, lower motoneuron involvement and dysarthria were predominant in two of the cases; the third had a cerebellar symptomatology. Hexosaminidase A activity, studied in leukocytes, was profoundly deficient when measured using the specific sulfated substrate, but nearly normal using a conventional assay (non-sulfated substrate). These results established the diagnosis of the unusual enzymological form of GM2-gangliosidosis known as the B1 variant, which had so far not been associated with an adult phenotype. Molecular studies are in progress to study genotype/phenotype correlations in this family in comparison with known mutations in the B1 variant and in adult GM2-gangliosidosis. This report also emphasizes that a metabolic etiology, leading to genetic counselling, should be considered in some familial degenerative neurological disorders.

[Idiopathic peri-cerebral enlargement in infants: simple anatomical variant or hemorrhagic risk factor?]. / Epanchement péricérébral idiopathique du nourrisson: simple variante anatomique ou facteur de risque hémorragique?

BACKGROUND: Idiopathic subarachnoid space enlargement (ISSE) is usually regarded as a benign lesion. CASE REPORTS: Two infants, 6 and 8 months old respectively, were hospitalized for neurological disorders revealing subdural hematoma. The first one was drowsy after an apparent life threatening event. The CT scan showed a recent subdural hematoma with ISSE. The outcome was spontaneously uneventful. The second patient presented a febrile hemiconvulsion preceding a status epilepticus. The diagnosis of empyema complicating subdural hematoma with ISSE was done on MRI. Recovery occurred after a 3 week course of parenteral antibiotics and 1 year of antiepileptic treatment. In these two cases, there was no history of head injury and the retrospective study of cranial perimeter growth curves showed acceleration before the acute event. CONCLUSION: The reputation of benignity is not usurped regarding the ISSE. Nevertheless, it must be recognized as a factor furthering emergence of subdural hematoma, even in absence of injury context.

[Leigh syndrome and leukodystrophy due to partial succinate dehydrogenase deficiency: regression with riboflavin]. / Syndrome de Leigh et leucodystrophie par déficit partiel en succinate déshydrogénase: régression sous riboflavine.

UNLABELLED: Succinate dehydrogenase (SDH) deficiency is rare. Clinical manifestations can appear in infancy with a marked impairment of psychomotor development with pyramidal signs and extrapyramidal rigidity. CASE REPORT: A 10-month-old boy developed severe neurological features, evoking a Leigh syndrome; magnetic resonance imaging showed features of leukodystrophy. A deficiency in the complex II respiratory chain (succinate dehydrogenase [SDH]) was shown. The course was remarkable by the regression of neurological impairment under treatment by riboflavin. The delay of psychomotor development, mainly involving language, was moderate at the age of 5 years. CONCLUSION: The relatively good prognosis of this patient, despite severe initial neurological impairment, may be due to the partial enzyme deficiency and/or riboflavin administration.

[Problems related to neurosurgical treatment of epilepsy in children]. / Problèmes posés par la neurochirurgie de l'épilepsie de l'enfant.

Neurosurgery of epilepsy in children has undergone rapid development during the past decade. This was justified by the high incidence of intractable epilepsy and its consequences on cognitive development. Any decision in the area of surgery must take in account specific etiology and the rapid maturation of the infant's brain. As in adulthood, both the epileptogenic and the functional zones must be identified, but this is a challenge when the brain is not mature and the functions not yet developed. In addition, the ability to recover must be determined. At the present time no precise methodology can be advised for presurgical work-up and surgical indications.

[Hot water epilepsy: a benign and underestimated form]. / L'épilepsie à l'eau chaude: une forme bénigne et méconnue.

BACKGROUND: Hot water epilepsy belongs to the group of reflex epilepsies. Seizures are provoked by hot water, due to the association of both cutaneous and heat stimuli. Described mainly in India and Japan, it seems to be rare in Europe where it occurs in young children. CASE REPORTS: Five infants aged between 6 months to 2 years had seizures during bathing with activity arrest, hypotonia and vasoactive modification. Sometimes clonic movements could be observed. The diagnosis was confirmed by EEG recorded during bath in the fives cases, with video for two of them. The course of the seizures and of the psychomotor development were favorable. CONCLUSION: Hot water epilepsy is a benign epilepsy. Its incidence could be underestimated because seizures can be confused with febrile convulsions or vagal fits.

[Surgery and epilepsy]. / Chirurgie et épilepsie.

Corpus callosotmy was introduced in 1940 as a palliative treatment for generalized epilepsies. The improvement of the surgical technique, and the simplification of the initial "total commissurotomy" made that procedure proposed in order to decrease the frequency and the severity of the seizures occurring in the secondary geralzed epilepsies. However the indication criteria remain unclear, due to the difficulty for analysing the results and the feterogenity of the series. A careful selection requiring a comprehensive epilepsy team remains mandatory despite the relative simplicity of the procedure.