Agenesis of the Corpus Callosum with Facial Dysmorphism and Intellectual Disability in Sibs Associated with Compound Heterozygous KDM5B Variants.

We studied a family in which the first-born child, a girl, had developmental delay, facial dysmorphism, and agenesis of the corpus callosum (ACC). The subsequent pregnancy was interrupted as the fetus was found to be also affected by ACC. Both cases were heterozygous for two KDM5B variants predicting p (Ala635Thr) and p (Ser1155AlafsTer4) that were shown to be in trans. KDM5B variants have been previously associated with moderate to severe developmental delay/intellectual disability (DD/ID), autism spectrum disorders (ASD), and dysmorphism in a few individuals, but the pathogenetic mechanisms are not clear yet as patients with both monoallelic and biallelic variants have been observed. Interestingly, one individual has previously been reported with ACC and severe ID in association with biallelic KDM5B variants. Together with the observations in this family, this suggests that agenesis of the corpus callosum may be part of the phenotypic spectrum associated with KDM5B variants and that the KDM5B gene should be included in gene panels to clarify the etiology of ACC both in the prenatal and postnatal setting.

A new family with an SLC9A6 mutation expanding the phenotypic spectrum of Christianson syndrome.

Using targeted next generation sequencing, we have identified a splicing mutation (c.526-9_526-5del) in the SLC9A6 gene in a 9-year-old boy with mild intellectual disability (ID), microcephaly, and social interaction disabilities. This intronic microdeletion leads to the skipping of exon 3 and to an in-frame deletion of 26 amino acids in the TM4 domain. It segregates with cognitive impairment or learning difficulties in other members of the family. Mutations in SLC9A6 have been reported in X-linked Christianson syndrome associating severe to profound intellectual deficiency and an Angelman-like phenotype with microcephaly, absent speech, ataxia with progressive cerebellar atrophy, ophthalmoplegia, epilepsy, and neurological regression. The proband and his maternal uncle both have an attenuated phenotype with mild ID, attention deficit disorder, speech difficulties, and mild asymptomatic cerebellar atrophy. The proband also have microcephaly. The mutation cosegregated with learning disabilities and speech difficulties in the female carriers (mother and three sisters of the proband). Detailed neuropsychological, speech, and occupational therapy investigations in the female carriers revealed impaired oral and written language acquisition, with dissociation between verbal and performance IQ. An abnormal phenotype, ranging from learning disability with predominant speech difficulties to mild intellectual deficiency, has been described previously in a large proportion of female carriers. Besides broadening the clinical spectrum of SLC9A6 gene mutations, we present an example of a monogenic origin of mild learning disability. © 2016 Wiley Periodicals, Inc.

Systematic MRI in NF1 children under six years of age for the diagnosis of optic pathway gliomas. Study and outcome of a French cohort.

BACKGROUND/PURPOSE: Optic pathway glioma (OPG) is the most common central nervous system tumor in children with neurofibromatosis type 1 (NF1), affecting 15-20% of patients. We reviewed the medical records of children systematically screened by ophthalmologic and MRI examinations to determine the influence of screening on the therapeutic management of children with OPG. METHODS: Data were collected on 306 newly diagnosed cases screened with systematic MRI from January 2001 to July 2007. In the OPG group, we distinguished the asymptomatic or symptomatic groups according to their initial status. RESULTS: Forty-five patients had confirmed OPG (14.7%). Thirty-six patients (80%) were asymptomatic and nine (20%) were symptomatic at the time of diagnosis with visual symptoms in six cases. The average age at OPG diagnosis was 3.4 years with six patients (13%) over six years old. Average follow-up was 7.7 years. Progression was observed in 16 cases (35%). Most patient conditions were managed conservatively (87%). Six children (13%) were treated with chemotherapy due to worsening visual function. All of these children had severe or mild visual impairment at the end of follow-up. CONCLUSION: Our study does not support a clear benefit of systematic MRI screening in NF1 children under six years old. Systematic neuroimaging in our study did not influence therapeutic management. Although OPG diagnosis was made early, treatment with chemotherapy did not improve the final visual outcome. If MRI remains the best tool for the diagnosis of cerebral and spinal pathologies in the NF1 population, our current study questions the usefulness of systematic MRI screening for OPG diagnosis. Conversely, this study suggests that the indication of neuroimaging should be dictated by the results of annual clinical and ophthalmological assessments.

Clinical presentation of severe viral encephalitis with known causative agents in children: a retrospective study on 16 patients hospitalized in a pediatric intensive care unit (2008-2011).

A retrospective analysis was conducted in a French pediatric hospital in Lyon. Subjects were 16 patients diagnosed with acute viral encephalitis with identified causative agents who were admitted to the pediatric intensive care unit from 2008 to 2011. The median length of stay was 6 days. The outcome was favorable for 77% of the patients. Analysis of biological and clinical findings based on causative agents did not reveal clinical patterns or neurological findings specific to the causal viruses. Nevertheless, uncommon clinical pictures and severe neurological complications were highlighted, in particular for children with influenza-related encephalitis and herpes simplex encephalitis. This case series exemplifies the difficulties, even pitfalls, in establishing a diagnosis of encephalitis, especially in neonates. It points out significant differences in the clinical presentation of encephalitis in children compared with clinical pictures described in previously published large-scale studies on encephalitis mainly conducted in adults.

A proposed diagnostic approach for infantile spasms based on a spectrum of variable aetiology.

AIM: To identify the aetiology of patients with infantile spasms and propose practical guidelines for diagnostic strategies. METHOD: We performed a retrospective study of children with West syndrome. Prenatal and birth medical history, characteristics of epilepsy, psychomotor development, biological and genetic screening, and aetiology were reported. Brain MRI was performed at least once and was repeated after two years of age if no aetiology was identified. RESULTS: Eighty children were included. Aetiology was identified in 40 children: 17 with acquired cause (seven with stroke and six with hypoxic-ischaemic encephalopathy) and 23 with developmental pathology (seven with tuberous sclerosis, eight with cerebral malformations, and eight with various genetic abnormalities). The yield of brain imaging was high, providing a diagnosis for 32 patients. Two subtle brain lesions were detected only after two years of age, based on subsequent MRI. Genetic testing provided a diagnosis for the remaining eight patients. INTERPRETATION: Although this is a retrospective study, the results provide a basis to review the aetiology of infantile spasms and confirm the role of cerebral MRI in first-line diagnosis. Cases with a genetic aetiology have been diagnosed with increasing frequency due to better diagnostic capabilities. We propose guidelines for a practical diagnostic approach and discuss the relevant use of genetics in the future.

Pre- and postnatal imaging of early cerebral damage in Sturge-Weber syndrome.

A case of prenatal diagnosis of Sturge-Weber syndrome associated with polymicrogyria is reported. The diagnosis was based on a unique association with unilateral hemispheric gyriform calcification, focal hemispheric atrophy and white matter changes on prenatal imaging including ultrasound and MRI. Polymicrogyria, which is exceptionally associated with Sturge-Weber syndrome, is suggestive of and reinforces the hypothesis of early impairment of the cerebral microvasculature related to leptomeningeal angioma, which may lead to abnormal cerebral development as early as the second trimester of pregnancy.

Similar early characteristics but variable neurological outcome of patients with a de novo mutation of KCNQ2.

BACKGROUND: Early onset epileptic encephalopathies (EOEEs) are dramatic heterogeneous conditions in which aetiology, seizures and/or interictal EEG have a negative impact on neurological development. Several genes have been associated with EOEE and a molecular diagnosis workup is challenging since similar phenotypes are associated with mutations in different genes and since mutations in one given gene can be associated with very different phenotypes. Recently, de novo mutations in KCNQ2, have been found in about 10% of EOEE patients. Our objective was to confirm that KCNQ2 was an important gene to include in the diagnosis workup of EOEEs and to fully describe the clinical and EEG features of mutated patients. METHODS: We have screened KCNQ2 in a cohort of 71 patients with an EOEE, without any brain structural abnormality. To be included in the cohort, patient's epilepsy should begin before three months of age and be associated with abnormal interictal EEG and neurological impairment. Brain MRI should not show any structural abnormality that could account for the epilepsy. RESULTS: Out of those 71 patients, 16 had a de novo mutation in KCNQ2 (23%). Interestingly, in the majority of the cases, the initial epileptic features of these patients were comparable to those previously described in the case of benign familial neonatal epilepsy (BFNE) also caused by KCNQ2 mutations. However, in contrast to BFNE, the interictal background EEG was altered and displayed multifocal spikes or a suppression-burst pattern. The ongoing epilepsy and development were highly variable but overall severe: 15/16 had obvious cognitive impairment, half of the patients became seizure-free, 5/16 could walk before the age of 3 and only 2/16 patient acquired the ability to speak. CONCLUSION: This study confirms that KCNQ2 is frequently mutated de novo in neonatal onset epileptic encephalopathy. We show here that despite a relatively stereotyped beginning of the condition, the neurological and epileptic evolution is variable.

Hashimoto's encephalopathy: identification and long-term outcome in children.

OBJECTIVE: To identify the clinical findings of Hashimoto's encephalopathy (HE) in children and assess their neurological outcome. METHODS: In this retrospective observational study of 42 children with encephalitis dominated by acute neuro-behavioral features, eight met the diagnostic criteria of HE. Their biological, EEG and brain MRI characteristics were compared to those of the other 34 children. Their clinical outcome was also compared to that of 14 children with Hashimoto's thyroiditis (HT). RESULTS: All eight HE children were girls and had high levels of anti-thyroid peroxidase (TPO) antibodies at onset (4043.3 ± 2969.8 IU/mL, inclusion criteria: TPO > 60 IU/mL) despite normal T4 and TSH levels in six of them. All HE children had abnormal EEG and brain MRI was abnormal in four of them. Relapses were observed in five children with a second relapse, despite steroid therapy, occurring sooner after the previous episode (median 18 days (range 17-188) vs 213 days (range 14-518)). Immunosuppressive therapy was started in all five children and two developed sequelae by the last follow-up visit (after 4 ± 1.3 years). Mean anti-TPO antibody titers were significantly higher in HE children than in those with Hashimoto's thyroiditis (HT) (4043.3 ± 2969.8 IU/mL vs 1980.9 ± 3449.9 IU/mL, p = 0.03). Four HE children subsequently developed hypothyroidism whereas only one HT patient presented encephalitis. CONCLUSION: HE is characterized by suggestive clinical symptoms with high levels of anti-TPO antibodies and, in most cases, normal T4 and TSH titers. Despite steroid treatment, relapses and sequelae are frequent. HE may evolve toward HT, but the reverse appears to be rare.

Mosaic 18q21.2 deletions including the TCF4 gene: a clinical report.

Pitt-Hopkins syndrome (PTHS) is characterized by distinctive facial dysmorphism, profound intellectual disability, and the possible occurrence of epilepsy and breathing anomalies. It is caused by haploinsufficiency of the TCF4 gene. No significant difference in clinical severity has been reported to date between PTHS patients carrying 18q21 deletions including the TCF4 gene, and those harboring TCF4 point mutations, suggesting a lack of genotype/phenotype correlation. Moreover, the size of 18q21 deletions including the TCF4 gene does not appear to have a significant effect on the phenotypic severity, suggesting that TCF4 haploinsufficiency is the most important prognostic factor in 18q deletions. We describe two unrelated patients presenting with clinical features reminiscent of PTHS and carrying mosaic interstitial 18q21 deletions characterized by array comparative genomic hybridization. One of the patients presented the lowest level of mosaic 18q21 deletion reported to date (5-10%). Our report and a review of the literature show that the mosaic status does not appear to have a significant effect on the clinical severity of 18q21 deletions, which are associated with a poor neurological outcome, whereas a mosaic TCF4 point mutation can result in a significantly milder phenotype. Malformations of internal organs are currently considered to be rare in PTHS. The patients described here had visceral anomalies, suggesting that a full morphological assessment, including heart and abdominal ultrasound scans, should be performed systematically in PTHS patients.

Familial nephrogenic syndrome of inappropriate antidiuresis: dissociation between aquaporin-2 and vasopressin excretion.

CONTEXT: Nephrogenic syndrome of inappropriate antidiuresis (NSIAD), the X-linked disease resulting from activating mutation of the vasopressin V2 receptor gene (AVPR2), is a recently described condition causative of episodes of hyponatremia in boys and male and female adults. OBJECTIVE: The objective of the study was the pathophysiological characterization of NSIAD. DESIGN: A family with NSIAD was identified and investigated for hyponatremic episodes and degrees of urine dilution defects. For the first time, the impact of the mutated V2R on aquaporin 2 (AQP2) excretion is reported. SETTING: The study was conducted at a referral center. PATIENTS: Five patients of seven carriers (two young brothers and their mother and her two sisters) were investigated together with age-matched controls. INTERVENTIONS: There were no interventions. RESULTS: In NSIAD patients, urinary AQP2 excretion occurred independently of concomitant vasopressin excretion and strongly correlated with urine osmolality, confirming direct AQP2 involvement in urine concentration. Water loading was followed by a very slow and incomplete elimination in the asymptomatic hemizygous boy with no suppression of AQP2 excretion and a delayed elimination in the heterozygous women because of an incomplete suppression of AQP2, and it induced hyponatremia in all NSIAD patients. Two hemizygous carriers presented with severe hyponatremia-induced seizures, and the repetition in one of them led to mental retardation. CONCLUSIONS: Hyponatremia was a constant and characteristic aspect of the abnormal response to even mild water-loading tests in an asymptomatic hemizygous child as well as heterozygous adults. We confirm the phenotypic variability of NSIAD, a disease that should be regarded in pediatric intensive care units in presence of severe and/or recurrent hyponatremia, and also in adults, because carriers are prone to hyponatremia.