De novo variants in SLC12A6 cause sporadic early-onset progressive sensorimotor neuropathy.

BACKGROUND: Charcot-Marie-Tooth disease (CMT) is a clinically and genetically heterogeneous disorder of the peripheral nervous system. Biallelic variants in SLC12A6 have been associated with autosomal-recessive hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC). We identified heterozygous de novo variants in SLC12A6 in three unrelated patients with intermediate CMT. METHODS: We evaluated the clinical reports and electrophysiological data of three patients carrying de novo variants in SLC12A6 identified by diagnostic trio exome sequencing. For functional characterisation of the identified variants, potassium influx of mutated KCC3 cotransporters was measured in Xenopus oocytes. RESULTS: We identified two different de novo missense changes (p.Arg207His and p.Tyr679Cys) in SLC12A6 in three unrelated individuals with early-onset progressive CMT. All presented with axonal/demyelinating sensorimotor neuropathy accompanied by spasticity in one patient. Cognition and brain MRI were normal. Modelling of the mutant KCC3 cotransporter in Xenopus oocytes showed a significant reduction in potassium influx for both changes. CONCLUSION: Our findings expand the genotypic and phenotypic spectrum associated with SLC12A6 variants from autosomal-recessive HMSN/ACC to dominant-acting de novo variants causing a milder clinical presentation with early-onset neuropathy.

Unilateral Hearing Loss Due to Cochlear Nerve Involvement as Isolated Symptom of a Primary Medulloblastoma.

Unilateral sensorineural hearing loss is a common symptom of vestibular schwannomas in adolescent patients with neurofibromatosis type 2 or sporadic vestibular schwannomas and is often the initial clinical feature. While rare cases of sensorineural impairment presenting as vision or hearing loss due to metastatic medulloblastoma are known, hearing loss as an isolated presenting symptom of primary malignant neuroepithelial tumors of the central nervous system has not been reported in the pediatric population so far. We present two adolescents with unilateral hearing loss due to cochlear nerve dysfunction as the only symptom of a primary nonmetastatic medulloblastoma of the WNT signaling pathway family members subgroup.

Cerebro-venous hypertension: a frequent cause of so-called "external hydrocephalus" in infants.

INTRODUCTION: External hydrocephalus (eHC) is commonly defined as a subtype of infant "hydrocephalus" consisting of macrocepahly associated with enlarged subarachnoid space and no or mild ventriculomegaly. This status is thought to be related to impaired CSF absorption because of arachnoid villi immaturity. However, other factors like the venous system might be involved in the development of the clinical picture. METHODS: All patients diagnosed with eHC received prospectively contrast-enhanced 3D MR phlebography. Venous sis abnormalities were graded depending on the number of affected sinus segments and type. External CSF space volume was quantified planimetrically. RESULTS: Seventeen patients with the typical clinical feature of eHC were included. In 15, venous sinus abnormalities were found. There was a significant correlation between the volume of the widened cortical subarachnoid space (CSAS) and the number of venous sinus segments affected. Conversely, ventricular volume was not correlated. CONCLUSION: These results support the hypothesis that impaired venous outflow plays a major role in external hydrocephalus development. Raised venous pressure increases intracranial pressure accelerating head growth, resulting in an enlargement of the cortical subarachnoid space. Increased venous pressure increases the capillary bed pressure and brain turgor preventing ventricular space to enlarge forcing displacement of ventricular CSF to the subarachnoid space. As a result, ventriculomegaly is rarely found. The descriptive term "external hydrocephalus" implying a primary etiology within the CSF system is misleading and this work supports the notion that venous hypertension is the leading cause of the clinical picture.

Congenital left temporal large arachnoid cyst causing intraorbital optic nerve damage in the second decade of life.

AIM: Intracranial sylvian arachnoid cysts are often asymptomatic lesions. We present a 16-year-old female patient with progressive loss of vision together with an unusual visual field defect on the left eye accompanied by headache. METHOD: A left frontotemporal sylvian arachnoid cyst was known since she was 9 months old, but observed ever since in the asymptomatic patient. Now, ophthalmological examination revealed bi-upper quadrant anopia on the left eye. Magnetic resonance imaging (MRI) and computed tomography showed erosion of the lateral orbital wall associated with intraorbital compression of the optic nerve by the cyst at the entrance into the optic canal. Microsurgical cyst fenestration to the basal cisterns was performed using a temporal mini-craniotomy. RESULT: Full improvement of vision and visual field defects was observed in the follow-up. On postoperative MRI, an increase of the tissue surrounding the optic nerve in the conus and better delineation at the entrance of optic canal was noted. CONCLUSION: Long-standing asymptomatic sylvian arachnoid cysts may suddenly produce severe unilateral visual deficits if the cyst erodes the lateral orbital wall. These deficits may rapidly revert to normal if surgical action is not delayed. If surveillance MRIs of sylvian arachnoid cysts show a narrowing of the conus diameter compared to the contralateral side, a yearly ophthalmological surveillance examination seems to be warranted in else wise asymptomatic patients.

Interstitial duplication of chromosome region 1q25.1q25.3: report of a patient with mild cognitive deficits, tall stature and facial dysmorphisms.

Isolated interstitial duplications of chromosome band 1q25 are apparently very rare; no patients with detailed molecular and clinical characterization of duplications restricted to this region have been published to date. We report on a 9-year-old girl with mild cognitive deficits, tall stature, macrocephaly and discrete dysmorphic features in whom a de novo interstitial 7.5 Mb duplication of 1q25.1q25.3 was detected by SNP array analysis (arr[hg19] 1q25.1q25.3(173,925,505-181,381,242)x3 dn). The duplicated region was inversely inserted into chromosome band 1q42.2: 46,XX,der(1)(pter→q42.2::q25.3→q25.1::q42.2→qter). Overexpression of one or several of the 87 genes in the duplicated interval was presumably the major causative factor for the clinical manifestations. Reports of additional patients with overlapping duplications will be needed to establish detailed karyotype-phenotype correlations and to gain a better understanding of the underlying pathomechanisms.

CASPR2 autoimmunity in children expanding to mild encephalopathy with hypertension.

OBJECTIVE: To delineate autoimmune disease in association with contactin-associated protein 2 (CASPR2) antibodies in childhood, we reviewed the clinical phenotype of children with CASPR2 antibodies. METHODS: Retrospective assessment of patients recruited through laboratories specialized in autoimmune CNS disease. RESULTS: Ten children with serum CASPR2 antibodies were identified (age at manifestation 18 months to 17 years). Eight children with CASPR2 antibody titers from ≥1:160 to 1:5,120 had complex autoimmune diseases with an age-dependent clinical phenotype. Two children with structural epilepsy due to CNS malformations harbored nonspecific low-titer CASPR2 antibodies (serum titers 1:80). The clinical symptoms of the 8 children with high-titer CASPR2 antibodies were general weakness (8/8), sleep dysregulation (8/8), dysautonomia (8/8) encephalopathy (7/8), neuropathic pain (7/8), neuromyotonia (3/8), and flaccid paresis (3/8). Adolescents (3/8) showed pain, neuromyotonia, and encephalopathy, whereas younger children (5/8) displayed severe hypertension, encephalopathy, and hormonal dysfunction mimicking a systemic disease. No tumors were identified. Motor symptoms remitted with immunotherapy. Mild behavioral changes persisted in 1 child, and autism spectrum disorder was diagnosed during follow-up in a young boy. CONCLUSION: High-titer CASPR2 antibodies are associated with Morvan syndrome in children as young as 2 years. However, CASPR2 autoimmunity mimics systemic disease and hypertensive encephalopathy in children younger than 7 years. The outcome following immunotherapy was mostly favorable; long-term behavioral impairment may occur in younger children.

Changes of third ventricle diameter (TVD) mirror changes of the entire ventricular system after initial therapy and during follow-up in pediatric hydrocephalus.

PURPOSE: Regular measurement of ventricular size is important in children with hydrocephalus. After closure of the fontanelle this is currently addressed by repetitive cranial MRI or CT imaging, coming along with risks of anaesthesia or radiation. As the third ventricle is accessible via the temporal bone window using ultrasound, determination of its diameter might be an easy and radiation-free alternative to assess the ventricular system. An essential precondition is that changes of the third ventricle diameter (TVD) mirror changes of the whole ventricular system. This study compares changes of TVD with changes of ventricular indices before and after initial treatment of hydrocephalus and during the following evolution. METHODS: MRT/CT images from 117 children with hydrocephalus were evaluated at time of diagnosis, after initial therapy and during follow-up with functional shunts. Measurements included axial TVD and three standard linear measures of the lateral ventricles (Evans Index - EI, fronto-occipital horn ratio - FOHR Index, and Cella Media Index - CMI). Furthermore, a correlation within subjects was calculated in 8 patients over the entire available follow-up. RESULTS: Relative changes of TVD were significantly correlated to relative changes of all ventricular indices (r = 0.48, r = 0.68 and r = 0.701 for EI, FOHR and CMI, respectively, p < 0.01). The correlation within subjects was outstanding for EI (r = 0.988), FOHR (r = 0.99) and CMI (r = 0.99). CONCLUSION: TVD showed a significant correlation with all three linear indices at the time of diagnosis and during follow-up changes independently of age, aetiology and ventricular width. TVD and its changes are therefore a reliable surrogate of changes in ventricular size in pediatric hydrocephalus undergoing treatment.

A highly polymorphic poly-glutamine stretch in the potassium channel KCNN3 in migraine.

OBJECTIVE: The present study is designed to further elucidate the molecular genetic basis of migraine with and without aura. BACKGROUND: Migraine is a common disease of as yet unknown etiology. Interest in ion channels in migraine has been spurred by molecular genetic findings in familial hemiplegic migraine, since familial hemiplegic migraine type 1 is caused by mutations in the calcium channel gene CACNA1A. METHODS: Given this role of ion channels in migraine, we assessed the potassium channel KCNN3 as a candidate gene for common migraine. We analyzed the highly polymorphic repeat region coding for a poly-glutamine stretch, which constitutes part of the cytoplasmic tail of the channel protein. RESULTS: We found an excess of the allele coding for 15 poly-glutamines in migraine patients. CONCLUSIONS: The potassium channel KCNN3 may thus be of pathophysiological importance in migraine with and without aura.