Missense variants in ANO4 cause sporadic encephalopathic or familial epilepsy with evidence for a dominant-negative effect

Anoctamins are a family of Ca2+-activated proteins that may act as ion channels and/or phospholipid scramblases with limited understanding of function and disease association. Here, we identified five de novo and two inherited missense variants in ANO4 (alias TMEM16D) as a cause of fever-sensitive developmental and epileptic or epileptic encephalopathy (DEE/EE) and generalized epilepsy with febrile seizures plus (GEFS+) or temporal lobe epilepsy. In silico modeling of the ANO4 structure predicted that all identified variants lead to destabilization of the ANO4 structure. Four variants are localized close to the Ca2+ binding sites of ANO4, suggesting impaired protein function. Variant mapping to the protein topology suggests a preliminary genotype-phenotype correlation. Moreover, the observation of a heterozygous ANO4 deletion in a healthy individual suggests a dysfunctional protein as disease mechanism rather than haploinsufficiency. To test this hypothesis, we examined mutant ANO4 functional properties in a heterologous expression system by patch-clamp recordings, immunocytochemistry, and surface expression of annexin A5 as a measure of phosphatidylserine scramblase activity. All ANO4 variants showed severe loss of ion channel function and DEE/EE associated variants presented mild loss of surface expression due to impaired plasma membrane trafficking. Increased levels of Ca2+-independent annexin A5 at the cell surface suggested an increased apoptosis rate in DEE-mutant expressing cells, but no changes in Ca2+-dependent scramblase activity were observed. Co-transfection with ANO4 wild-type suggested a dominant-negative effect. In summary, we expand the genetic base for both encephalopathic sporadic and inherited fever-sensitive epilepsies and link germline variants in ANO4 to a hereditary disease.

Laser interstitial thermal therapy in pediatric cerebellar epilepsy

Cerebellar lesional epilepsy is rare, commonly manifesting in early life and posing diagnostic and treatment challenges. Seizure semiology may be subtle, with repetitive eye blinking, face twitching, and irregular breathing, while EEG commonly remains unremarkable. Pharmacoresistance is the rule, and surgical intervention is the only treatment with the potential for cure. Novel minimally invasive techniques, such as laser interstitial thermal therapy (LITT), are emerging for surgically less accessible, deep-seated epileptogenic lesions. We report the case of a patient who presented with peculiar eye and face movements occurring episodically and stereotypically since the first weeks of life and was later diagnosed with cerebellar epilepsy related to a hamartoma. Refractory daily seizures, unresponsive to antiseizure medication, were followed by increasingly prominent gait ataxia and delayed speech development. Staged LITT was performed in two consecutive sessions at 3 and 4 years, leading to seizure cessation, neurological improvement, and developmental gains over a postsurgical follow-up period of 8 months. Our case highlights cerebellar lesional epilepsy as a rare but important differential diagnosis in children with paroxysmal disorders predominantly involving the face. Furthermore, we illustrate the radiological correlates of neurocognitive deficit related to the cerebellar lesion, manifesting as cerebello-cerebral diaschisis. Most importantly, our observations showcase LITT as a safe and effective therapeutic approach in cerebellar lesional epilepsy and an attractive alternative to open brain surgery, especially for deep-seated lesions in the pediatric population.

The atypical sphingolipid SPB 18:1(14Z);O2 is a biomarker for DEGS1 related hypomyelinating leukodystrophy

Sphingolipids (SL) represent a structurally diverse class of lipids that are central to cellular physiology and neuronal development and function. Defects in the sphingolipid metabolism are typically associated with nervous system disorders. The C4-dihydroceramide desaturase (DEGS1) catalyzes the conversion of dihydroceramide to ceramide, the final step in the SL de-novo synthesis. Loss of function mutations in DEGS1 cause a hypomyelinating leukodystrophy, which is associated with increased plasma dihydrosphingolipids (dhSL) and with the formation of an atypical SPB 18:1(14Z);O2 metabolite. Here, we characterize two novel DEGS1 variants of unknown significance (VUS), provide a structural model with a predicted substrate binding site, and propose a regulatory link between DEGS1 and fatty acid desaturase 3 (FADS3). Both VUS involve single amino acid substitutions near the C-terminus within conserved regions of the enzyme. Patient 1 (p.R311K variant) shows severe progressive tetraspasticity, intellectual disability, and epilepsy in combination with brain magnetic resonance imaging (MRI) findings, typical for DEGS1-related leukodystrophy. Patient 2 (p.G270E variant) presents with delayed psychomotor development, oculomotor apraxia, and a normal brain MRI. Plasma from the p.R311K carrier showed a significantly elevated dhSL species and the presence of SPB 18:1(14Z);O2, while the plasma SL profile for the p.G270E variant was not altered. This suggests the p.R331K variant is pathogenic, while the p.G270E appears benign. As an increase in dihydroSL species is also seen in other pathological disorders of the SL metabolism, the SPB 18:1(14Z);O2 seems to be a more specific biomarker to discriminate between pathogenic and benign DEGS1 variants.

Genetic Analysis in a Swiss Cohort of Bilateral Congenital Cataract

Importance

Identification of geographic population-based differences in genotype and phenotype heterogeneity are important for targeted and patient-specific diagnosis and treatment, counseling, and screening strategies.

Objective

To report disease-causing variants and their detailed phenotype in patients with bilateral congenital cataract from a single center in Switzerland and thereby draw a genetic map and perform a genotype-phenotype comparison of this cohort.

Design, Setting, and Participants

This clinical and molecular-genetic cohort study took place through the collaboration of the Department of Ophthalmology at the University Hospital Zurich and the Institute of Medical Molecular Genetics, University of Zurich, Schlieren, Switzerland. Thirty-seven patients from 25 families with different types of bilateral congenital cataract were included. All participating family members received a comprehensive eye examination. Whole exome sequencing was performed in the index patients, followed by a filtering process to detect possible disease-associated variants in genes previously described in association with congenital cataract. Probable disease-causing variants were confirmed by Sanger sequencing in available family members. All data were collected from January 2018 to June 2020, and the molecular-genetic analyses were performed from January 2019 to July 2020.

Main Outcomes and Measures

Identification of the underlying genetic causes of bilateral congenital cataract, including novel disease-causing variants and phenotype correlation.

Results

Among the 37 patients (18 [49%] male and 19 [51%] female; mean [SD] age, 17.3 [15.9] years) from 25 families, pathogenic variants were detected in 20 families (80% detection rate), which included 13 novel variants in the following genes: BCOR, COL4A1, CRYBA2, CRYBB2, CRYGC, CRYGS, GJA3, MAF, NHS, and WFS1. Putative disease-causing variants were identified in 14 of 20 families (70%) as isolated cases and in 6 of 20 families (30%) with syndromic cases. A recessive variant in the CRYBB2 gene in a consanguineous family with 2 affected siblings showing a nuclear and sutural cataract was reported in contrast to previously published reports. In addition, the effect on splicing in a minigene assay of a novel splice site variant in the NHS gene (c.[719-2A>G]) supported the pathogenicity of this variant.

Conclusions and Relevance

This study emphasizes the importance of genetic testing of congenital cataracts. Known dominant genes need to be considered for recessive inheritance patterns. Syndromic types of cataract may be underdiagnosed in patients with mild systemic features.

Heterozygous truncating variants in SUFU cause congenital ocular motor apraxia

Purpose

This study aimed to delineate the genetic basis of congenital ocular motor apraxia (COMA) in patients not otherwise classifiable.

Methods

We compiled clinical and neuroimaging data of individuals from six unrelated families with distinct clinical features of COMA who do not share common diagnostic characteristics of Joubert syndrome or other known genetic conditions associated with COMA. We used exome sequencing to identify pathogenic variants and functional studies in patient-derived fibroblasts.

Results

In 15 individuals, we detected familial as well as de novo heterozygous truncating causative variants in the Suppressor of Fused (SUFU) gene, a negative regulator of the Hedgehog (HH) signaling pathway. Functional studies showed no differences in cilia occurrence, morphology, or localization of ciliary proteins, such as smoothened. However, analysis of expression of HH signaling target genes detected a significant increase in the general signaling activity in COMA patient–derived fibroblasts compared with control cells. We observed higher basal HH signaling activity resulting in increased basal expression levels of GLI1, GLI2, GLI3, and Patched1. Neuroimaging revealed subtle cerebellar changes, but no full-blown molar tooth sign.

Conclusion

Taken together, our data imply that the clinical phenotype associated with heterozygous truncating germline variants in SUFU is a forme fruste of Joubert syndrome.

Epidemiology, Clinical Features, and Use of Early Supportive Measures in PHACE Syndrome: A European Multinational Observational Study

BACKGROUND

PHACE syndrome is a rare inborn condition characterized by large facial hemangiomas and variable malformations of the arterial system, heart, central nervous system, and eyes. According to Orphanet estimates, the prevalence is <1.0 per million. Data from Europe are limited to small case series, and there are no population-based data available.

OBJECTIVES

We conducted the present study to provide population-based estimates of the disease prevalence of PHACE syndrome in children in Germany, Switzerland, and Austria. We compared these first systematic data on PHACE syndrome from Europe to published data from the PHACE Syndrome International Clinical Registry and Genetic Repository (USA). Clinical features in our cohort with PHACE syndrome were assessed in detail, including the need for early supportive measures.

METHODS

We used a population-based approach by means of a previously well-established network of child neurologists from Germany, Switzerland, and Austria ("ESNEK") to identify potential patients. The patients' guardians and child neurologists were asked to fill in questionnaires developed in collaboration with the International PHACE Registry.

RESULTS

We identified 19 patients with PHACE syndrome. Estimated prevalence rates were 6.5 per million in Switzerland, 0.59 per million in Germany, and 0.65 per million in Austria. A subset of 10 patients from Germany and Switzerland participated in our study, providing detailed clinical assessment (median age: 2.5 years; 9 females, 1 male). Cerebrovascular involvement was frequent (80%). Facial hemangioma extent correlated significantly with the number of organs involved (p = 0.011). In 9 out of 10 patients, facial hemangiomas were treated successfully with oral propranolol. Baseline demographic data as well as the rate of cerebrovascular and cardiovascular anomalies were in line with those from the US International PHACE Registry and other published PHACE cohorts.

CONCLUSIONS

Our study provides population-based estimates for PHACE syndrome in 3 German-speaking countries. The data from Switzerland indicate that PHACE syndrome may be more prevalent than demonstrated by previous reports. Underreporting of PHACE syndrome in Germany and Austria likely accounts for the differences in prevalence rates. The clinical observation of a potential association between the size of facial hemangioma and extent of organ involvement warrants further investigation.

[Ocular Phenotype and Complications in Patients with Tuberous Sclerosis Complex (TSC)]

BACKGROUND

Evaluation and comparison of the ocular phenotype in patients diagnosed with tuberous sclerosis complex (TSC). Analysis of ocular complications during follow-up.

PATIENTS AND METHODS

A retrospective chart review was performed of patients with TSC who had received an ocular examination at the eye clinic of the University Hospital Zurich. Data were analysed on visual acuity (VA) assessment, refraction, anterior and posterior eye examination including the distinction of different types of hamartomas and, when available, visual fields. The study was approved by the Cantonal Ethics Committee of Zurich.

RESULTS

A total of 30 patients who were diagnosed with TSC (19 female, 11 male) were included in the analysis. The age at first examination varied from 7 months to 44 years (mean 13.3 years, standard deviation 11.31). 17/30 patients received a follow-up examination between 4 months and 19 years (mean 4.3 years, standard deviation 5.24). Data of VA were available in 26/30 patients, of whom 22 had normal vision in both eyes. The causes of reduced VA in the 4 patients were: complications of a subependymal giant cell astrocytoma followed by a bilateral optic nerve atrophy; vigabatrin-associated optic atrophy; anterior segment dysgenesis; unilateral amblyopia. Adequate VA testing was not possible in 4 patients because of intellectual disabilities. Retinal hamartomas were described in 15/30 patients: 8 unilateral, 7 bilateral. The flat hamartoma type was described in 10/15 patients, the multinodular type in 6/15 patients.

CONCLUSIONS

The ocular phenotype in our patient cohort shows similar TSC involvement to that described in the literature. Patients diagnosed with TSC require regular ophthalmic examinations to diagnose secondary ocular complications, such as papilloedema, severe vision loss or visual field constriction.

Infantile Basal Ganglia Stroke after Mild Head Trauma Associated with Mineralizing Angiopathy of Lenticulostriate Arteries: An Under Recognized Entity

Basal ganglia infarction in young children, mostly after mild head trauma, has been repeatedly reported. The pathogenesis and the risk factors are not fully understood. Lenticulostriate vasculopathy, usually referred to as basal ganglia calcification, is discussed as one of them. We describe five young (7-13 months old on presentation) male children who suffered from hemiparesis due to ischemic stroke of the basal ganglia, four of them after minor head trauma. All of them had calcification in the basal ganglia visible on computed tomography or cranial ultrasound but not on magnetic resonance imaging. Follow-up care was remarkable for recurrent infarction in three patients. One patient had a second symptomatic stroke on the contralateral side, and two patients showed new asymptomatic infarctions in the contralateral basal ganglia on imaging. In view of the scant literature, this clinic-radiologic entity seems under recognized. We review the published cases and hypothesize that male sex and iron deficiency anemia are risk factors for basal ganglia stroke after minor trauma in the context of basal ganglia calcification in infants. We suggest to perform appropriate targeted neuroimaging in case of infantile basal ganglia stroke, and to consider prophylactic medical treatment, although its value in this context is not proven.

Nosological delineation of congenital ocular motor apraxia type Cogan: an observational study

Background

The nosological assignment of congenital ocular motor apraxia type Cogan (COMA) is still controversial. While regarded as a distinct entity by some authorities including the Online Mendelian Inheritance in Man catalog of genetic disorders, others consider COMA merely a clinical symptom.

Methods

We performed a retrospective multicenter data collection study with re-evaluation of clinical and neuroimaging data of 21 previously unreported patients (8 female, 13 male, ages ranging from 2 to 24 years) diagnosed as having COMA.

Results

Ocular motor apraxia (OMA) was recognized during the first year of life and confined to horizontal pursuit in all patients. OMA attenuated over the years in most cases, regressed completely in two siblings, and persisted unimproved in one individual. Accompanying clinical features included early onset ataxia in most patients and cognitive impairment with learning disability (n = 6) or intellectual disability (n = 4). Re-evaluation of MRI data sets revealed a hitherto unrecognized molar tooth sign diagnostic for Joubert syndrome in 11 patients, neuroimaging features of Poretti-Boltshauser syndrome in one case and cerebral malformation suspicious of a tubulinopathy in another subject. In the remainder, MRI showed vermian hypo-/dysplasia in 4 and no abnormalities in another 4 patients. There was a strong trend to more severe cognitive impairment in patients with Joubert syndrome compared to those with inconclusive MRI, but otherwise no significant difference in clinical phenotypes between these two groups.

Conclusions

Systematical renewed analysis of neuroimaging data resulted in a diagnostic reappraisal in the majority of patients with early-onset OMA in the cohort reported here. This finding poses a further challenge to the notion of COMA constituting a separate entity and underlines the need for an expert assessment of neuroimaging in children with COMA, especially if they show cognitive impairment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-016-0486-z) contains supplementary material, which is available to authorized users.

Pseudotumoral hemicerebellitis as a mimicker of Lhermitte-Duclos disease in children: does neuroimaging help to differentiate them?

The clinical presentation and neuroimaging findings of children with pseudotumoral hemicerebellitis (PTHC) and Lhermitte-Duclos disease (LDD) may be very similar. The differentiation between these entities, however, is important because their management and prognosis are different. We report on three children with PTHC. For all three children, in the acute situation, the differentiation between PTHC and LDD was challenging. A review of the literature shows that a detailed evaluation of conventional and neuroimaging data may help to differentiate between these two entities. A striated folial pattern, brainstem involvement, and prominent veins surrounding the thickened cerebellar foliae on susceptibility weighted imaging favor LDD, while post-contrast enhancement and an increased choline peak on (1)H-Magnetic resonance spectroscopy suggest PTHC.

The distribution pattern of segmental vitiligo: clues for somatic mosaicism

BACKGROUND

Segmental vitiligo is characterized by a unilateral and localized distribution. So far, the underlying mechanism is still an enigma.

OBJECTIVES

 To get an insight into the aetiopathogenesis of segmental vitiligo by comparison with the distribution pattern of dermatoses with a possible mosaic or neurogenic background.

METHODS

In this retrospective observational study the distribution pattern of 724 unilateral, linear or band-shaped control lesions was compared with 181 segmental vitiligo lesions. Clinical photographs were used to score similarities according to a defined grading system (scale ranging from 0 for no similarities to 4 for complete similarity). Control lesions were evaluated both individually and after grouping into different cell types.

RESULTS

In general, only a minority of cases (36·9%), showed similarities (grade 1-4) between control lesions and segmental vitiligo. Grade 2-4 similarities were seen mainly in segmental lentiginosis (73·7%, P < 0·001). The best grade for correspondence (grade 3-4) was observed significantly more only in segmental lentiginosis (36·8% vs. 3·5%, P<0·001) and epidermal naevus verrucosus (12·5% vs. 3·7%, P=0·008) compared with the other control lesions. The distribution pattern of segmental vitiligo significantly overlapped those of other disorders originating from melanocytes.

CONCLUSIONS

 Our results demonstrate that the distribution pattern of segmental vitiligo is not entirely similar to any other skin disease, although some mosaic skin disorders have more overlap with segmental vitiligo than others. The remarkable clinical similarity with several cases of mosaic diseases involving melanocytes supports the hypothesis that cutaneous mosaicism may be involved in segmental vitiligo.

Phacomatosis pigmentovascularis and extensive venous malformation of brain vessels: an unknown association or a new vascular neurocutaneous syndrome?

We report on a 16-year-old intelligent and sportive boy with the cutaneous findings of phacomatosis pigmentovascularis unclassifiable type.The skin anomaly was lateralised to his left body side since birth, fading over the years. Because of headache and dizziness, brain magnetic resonance imaging was performed, which revealed an impressive enlargement of subependymal, deep and superficial medullary veins on the right side combined with a mild atrophy of the ipsilateral parietal region. We propose to investigate patients with phacomatosis pigmentovascularis for associated venous brain malformations with adequate imaging techniques.

Association of lentiginous mosaicism and congenital cataract in a girl

Partial unilateral lentiginosis (PUL) is a rare pigmentary disorder characterized by multiple lentigines on otherwise normal skin affecting one side of the body. We report on a girl with an extensive form of bilateral lentiginosis with systematized segmental distribution and a unilateral congenital cataract. The arrangement of the lentigines is reminiscent of a checkerboard pattern. The benign condition is discussed in the context of systemic diseases with lentigines.

Marchiafava-Bignami-like injury of the corpus callosum in an infant

We report on a 16-month-old boy who presented with truncal ataxia and intermittent nystagmus. Magnetic resonance imaging (MRI) at 19 months showed a T (2)-hyperintensity of the splenium and the genu of the corpus callosum with extension into the adjacent frontal white matter. Diffusion tensor imaging (DTI) revealed a corresponding area of restricted diffusion, suggesting cytotoxic oedema. The extent and localisation of the signal abnormalities mimic tissue injury as seen in Marchiafava-Bignami disease (MBD). Metabolic investigations were normal. Follow-up imaging at 24 months showed a similar T (2)-hyperintensity of the corpus callosum and white matter while on DTI the cytotoxic oedema had resolved. Clinically a remaining truncal and gait ataxia, clumsiness and a developmental delay is seen. Goal of this case report is (a) to present a rare case of Marchiafava-Bignami-like injury of the corpus callosum in an infant and (b) to discuss the neuroradiological imaging findings including MRI and DTI.

Severe neurological impairment in hereditary methaemoglobinaemia type 2

Recessive congenital methaemoglobinaemia (RCM) due to NADH-cytochrome b5 reductase (cytb5r) deficiency is a very rare disorder. We report on two unrelated patients (4 and 2.5 years old) with RCM type 2. Developmental delay was obvious at the age of 4 months. On follow-up, both children showed severe tetraspastic cerebral palsy, profound cognitive impairment, strabismus, impressive secondary microcephaly and failure to thrive. One novel mutation in the DIA1gene was identified. Prenatal diagnosis was successfully done in both families by mutation analysis in chorionic villi or measurement of cytb5r in fetal amniotic cells.

CONCLUSION

Due to the severity of this disease and its 25% recurrence risk, prenatal diagnosis should be made available to all affected families.

Rhombencephalosynapsis: clinical findings and neuroimaging in 9 children

Rhombencephalosynapsis is a rare congenital abnormality characterised by dorsal fusion of the cerebellar hemispheres, agenesis or hypogenesis of the vermis, fusion of dentate nuclei and superior cerebellar peduncles. We describe 9 children, aged 1.5 to 6 years, with rhombencephalosynapsis. Isolated rhombencephalosynapsis was found in 2 patients, hydrocephalus in 3 children and another 3 children had ventriculomegaly. Additional supratentorial abnormalities were documented in 5 patients. Clinical findings ranged from mild truncal ataxia and normal cognitive abilities to severe cerebral palsy and mental retardation. No correlation between clinical findings and magnetic resonance imaging could be established so far.

Trichothiodystrophy with severe cardiac and neurological involvement in two sisters

Trichothiodystrophy or sulphur-deficient brittle hair is a clinical marker for several autosomal recessive neurocutaneous syndromes. The typical hair abnormality is frequently associated with many alterations affecting the skin, nervous system, eyes and bones as well as the immune, gonadal and endocrine systems. We report the first cases of dilated cardiomyopathy in two sisters with trichothiodystrophy, leading to cerebral infarction in the younger one. In addition, both suffer from severe hearing impairment, osteosclerosis, and psychomotor retardation with central hypomyelination.

CONCLUSION

Severe cardiac involvement and stroke may be associated features of trichothiodystrophy.

Long-term outcome in children with congenital unilateral facial nerve palsy

During a 20-year period (1980 - 1999) 12 children with isolated congenital unilateral facial nerve palsy were seen at our hospital. The only child delivered by forceps made a full recovery from his palsy within two months, whereas functional improvement in patients with non-traumatic delivery was generally poor. In two patients the palsy affected predominantly the upper periocular region. In 10 children the lower facial region seemed to be mainly involved. Cognitive outcome was within normal limits, with one exception. Conventional neuroimaging was not contributory to the understanding of the pathogenetic mechanisms. We conclude that the majority of congenital unilateral facial nerve palsies are not of traumatic origin and carry a poor functional prognosis.