Clinical features and magnesium levels: Novel insights in 15q11.2 BP1-BP2 copy number variants.

BACKGROUND: Investigating copy number variations (CNVs) such as microdeletions or microduplications can significantly contribute to discover the aetiology of neurodevelopmental disorders. 15q11.2 genomic region, including NIPA1 and NIPA2 genes, contains a recurrent but rare CNV, flanked by the break points BP1 and BP2. Both BP1-BP2 microdeletion and microduplication have been associated with intellectual disability (ID), neuropsychiatric/behavioural disturbances and mild clinical features, even if with incomplete penetrance and variable expressivity. The pathogenic role of this CNV is quite unclear though. Unknown variants in other DNA regions and parent-of-origin effect (POE) are some of the mechanisms that have been proposed as an explanation of the wide phenotypic variability. As NIPA1 and NIPA2 encode for proteins that mediate magnesium (Mg2+ ) metabolism, it has been suggested that urinary Mg2+ levels could potentially represent informative and affordable biomarkers for a rapid screening of 15q11.2 duplications or deletions. Furthermore, magnesium supplementation has been proposed as possible therapeutic strategy. METHODS: Thirty one children with ID and/or other neurodevelopmental disorders carrying either a duplication or a deletion in 15q11.2 BP1-BP2 region have been recruited. When available, blood samples from parents have been analysed to identify the CNV origin. All participants underwent family and medical data collection, physical examination and neuropsychiatric assessment. Electroencephalogram (EEG) and brain magnetic resonance imaging (MRI) scan were performed in 15 children. In addition, 11 families agreed to participate to the assessment of blood and urinary Mg2+ levels. RESULTS: We observed a highly variable phenotypic spectrum of developmental issues encompassing ID in most subjects as well as a variety of behavioural disorders such as autism and attention-deficit disorder/attention-deficit hyperactivity disorder. Dysmorphic traits and malformations were detected only in a minority of the participants, and no clear association with growth anomalies was found. Abnormal brain MRI and/or EEG were reported respectively in 64% and 92% of the subjects. Inheritance assessment highlighted an excess of duplication of maternal origin, while cardiac alterations were detected only in children with 15q11.2 CNV inherited from the father. We found great variability in Mg2+ urinary values, without correlation with 15q11.2 copy numbers. However, the variance of urinary Mg2+ levels largely increases in individuals with 15q11.2 deletion/duplication. CONCLUSIONS: This study provides further evidence that 15q11.2 BP1-BP2 CNV is associated with a broad spectrum of neurodevelopmental disorders and POE might be an explanation for clinical variability. However, some issues may question the real impact of 15q11.2 CNV on the phenotype in the carriers: DNA sequencing could be useful to exclude other pathogenic gene mutations. Our results do not support the possibility that urinary Mg2+ levels can be used as biomarkers to screen children with neurodevelopmental disorders for 15q11.2 duplication/deletion. However, there are evidences of correlations between 15q11.2 BP1-BP2 CNV and Mg2+ metabolism and future studies may pave the way to new therapeutic options.

Novel POMGNT1 point mutations and intragenic rearrangements associated with muscle-eye-brain disease.

Congenital muscular dystrophies due to defects in genes encoding proteins involved in α-dystroglycan (α-DG) glycosylation are a heterogeneous group of muscle disorders variably associated with central nervous system and eye abnormalities. One of the more severe is muscle-eye-brain disease (MEB). Mutations in genes coding for proven or putative glycosyltransferases (POMT1, POMT2, POMGnT1, fukutin, FKRP, and LARGE), the DPM3 gene encoding a DOL-P-Man synthase subunit, and the DAG1 gene encoding α-dystroglycan, have been associated with altered α-DG glycosylation. We report new POMGnT1 mutations and evaluate protein expression in 3 patients and 2 foetuses with variably severe MEB features. We identify two new point mutations (c.643C>T, c.1863delC), one new intragenic rearrangement (deletion of exons 2-8), and a new intron retention (between exons 21 and 22) resulting from a known point mutation c.1895+1G>T. Our study provides further evidence that rearrangements of the POMGnT1 gene are relatively common. Importantly, if heterozygous, they can be missed on standard genomic DNA sequencing. POMGNT1 protein analysis in 3 patients showed that the severity of the phenotype does not correlate with protein expression. Cerebral MRI is important for identifying MEB and α-dystroglycanopathy phenotypes in children and foetuses, and hence for directing the genetic analysis.

Congenital muscular dystrophies with cognitive impairment. A population study.

BACKGROUND: Cognitive impairment has been reported in a significant proportion of patients with congenital muscular dystrophies (CMD), generally associated with brain changes. OBJECTIVES: The aim of this study was to establish 1) the overall prevalence of CMD and cognitive impairment in the Italian population; 2) the frequency of individual genetically defined forms; and 3) the presence of distinct phenotypes not associated with mutations in the known genes. METHODS: We included all patients with CMD and cognitive impairment followed in all the Italian tertiary neuromuscular centers. Clinical, brain MRI, and morphologic data were collected. Genetic screening of the known genes was performed according to clinical and muscle biopsy findings. RESULTS: Ninety-two of the 160 (58%) patients with CMD followed in our centers had cognitive impairment. alpha-Dystroglycan (alpha-DG) reduction on muscle biopsy was found in 73/92 (79%), with 42/73 carrying mutations in the known genes. Another 6/92 (7%) showed a laminin alpha2 deficiency on muscle biopsy and 5 of the 6 carried mutations in LAMA2. The remaining 13/92 (14%) patients had normal alpha-DG and laminin alpha2 expression on muscle. CONCLUSIONS: This is the first population study establishing the prevalence of CMD and cognitive impairment and providing a classification on the basis of clinical, MRI, and genetic findings. We also showed that cognitive impairment was not always associated with alpha-DG or laminin alpha2 reduction or with structural brain changes.

Cognitive and behavioural effects of migraine in childhood and adolescence.

Since cognitive and behavioural characteristics of paediatric migraine sufferers have yet to be adequately defined, in this study we assessed the effect of migraine on the interictal functioning of children and adolescents by comparing the performance of two patient groups, 17 migraine sufferers with aura (MA) and 31 without aura (MoA) and by correlating the duration of the disorder, the frequency of attacks and interictal period with neuropsychological and behavioural findings. Both patient groups had cognitive performance within normal range except for a significant delay in the reaction time (RT) task. Both MA and MoA revealed a behavioural phenotype characterized by internalizing problems on Child Behaviour Check List (CBCL) scales. Slower RT to simple visual stimuli may be an early sign of a subclinical neuropsychological dysfunction, significantly correlated with the frequency of headache attacks and interictal period. The lack of a control group and other methodological limitations, such as patient selection bias and unadjusted P-value for multiple testing, make it difficult to give this finding a clearcut meaning. Further studies are needed on larger samples compared with a control group.

Unilateral frontal lobe epilepsy affects executive functions in children.

Very few studies to date have investigated the neuropsychological changes detectable in children suffering from frontal lobe epilepsy (FLE). The aim of the present study was to assess the effects of FLE on cognitive and executive functions in childhood. The sample includes 17 children with a frontal epileptogenic focus (10 right and 7 left), with no evidence of anatomical brain damage. These subjects were assessed by means of a battery of tests to investigate executive functioning. The results emphasised the presence of selective impairments of frontal lobe functions without evidence of deficits in global intellectual functioning. No side-specific deficits were detected, while an earlier onset of epilepsy and the duration of the disorder, but not the seizures frequency, were found to correspond with more severe deficits in some specific frontal lobe functions.

Mutation analysis of the NSD1 gene in a group of 59 patients with congenital overgrowth.

Sotos syndrome is characterized by pre- and post-natal overgrowth, typical craniofacial features, advanced bone age, and developmental delay. Some degree of phenotypic overlap exists with other overgrowth syndromes, in particular with Weaver syndrome. Sotos syndrome is caused by haploinsufficiency of the NSD1 (nuclear receptor SET domain containing gene 1) gene. Microdeletions involving the gene are the major cause of the syndrome in Japanese patients, whereas intragenic mutations are more frequent in non-Japanese patients. NSD1 aberrations have also been described in some patients diagnosed as Weaver syndrome. Some authors have suggested a certain degree of genotype-phenotype correlation, with a milder degree of overgrowth, a more severe mental retardation, and a higher frequency of congenital anomalies in microdeleted patients. Data on larger series are needed to confirm this suggestion. We report here on microdeletion and mutation analysis of NSD1 in 59 patients with congenital overgrowth. Fourteen novel mutations, two previously described and one microdeletion were identified. All patients with a NSD1 mutation had been clinically classified as "classical Sotos," although their phenotype analysis demonstrated that some major criteria, such as overgrowth and macrocephaly, could be absent. All patients with confirmed mutations shared the typical Sotos facial gestalt. A high frequency of congenital heart defects was present in patients with intragenic mutations, supporting the relevance of the NSD1 gene in the pathogenesis of this particular defect.

Intrathecal methotrexate affects cognitive function in children with medulloblastoma.

BACKGROUND: Cognitive impairment occurs after malignant brain tumor treatment in children, following brain radiotherapy and systemic and intrathecal chemotherapy. OBJECTIVES: 1) To compare two groups of children who underwent surgery for cerebellar medulloblastoma with their cousins and siblings, assessing intelligence, executive function, attention, visual perception, and short-term memory. Both groups were treated with the same combined radiotherapy-chemotherapy, but differed in that only one group received intrathecal methotrexate (MTX+). 2) To relate these measures to MRI findings (leukomalacia). RESULTS: The two groups performed worse than their control subjects in all tests. The MTX+ group younger than 10 years performed significantly worse in all tests, particularly executive ones. The group older than 10 years performed significantly worse only in short-term memory. Younger patients without MTX performed significantly worse than controls only in some neuropsychological measures; there were no differences between older patients and control subjects. Only in the MTX+ group was there a direct correlation between extent of leukomalacia and performance in some tests. CONCLUSIONS: The administration of intrathecal methotrexate to children with medulloblastoma worsens the cognitive deficits induced by chemotherapy and radiotherapy. The use of intrathecal methotrexate in the treatment of medulloblastoma and other malignancies should be reassessed.

Papillitis as an onset sign of Leber's hereditary optic neuropathy: a case report.

Leber's hereditary optic neuropathy is a maternally transmitted disease resulting from a point mutation in mitochondrial (mt) DNA. In this report we describe a case of Leber's disease with typical clinical findings but atypical ophthalmoscopic presentation. A 14-year-old boy developed severe loss of vision acuity in the left eye, with only partial recovery, followed 4 months later by the same symptoms in the right eye. Fundoscopic examination showed hyperemic papilla on the right eye and optic disc pallor on the left eye. Polymerase chain reaction analysis of lymphocytic mt-DNA revealed a point mutation at 11778. Leber's disease should be considered in young patients (not always male) with sudden visual loss and simple papillary involvement at fundoscopic examination but without the typical telangiectatic microangiopathy.

A case of 3-methylglutaconic aciduria misdiagnosed as cerebral palsy.

3-Methylglutaconic aciduria is a rare hereditary metabolic disorder characterized by increased urinary excretion of 3-methylglutaconic and 3-methylglutaric acids. Four clinical forms are recognized. This study presents the case of a 5-year-old male with type IV 3-methylglutaconic aciduria, initially diagnosed as "static encephalopathy." The slow evolution and other clinical characteristics, together with cerebral magnetic resonance imaging (MRI) findings, eventually directed the diagnosis to organic aciduria that was confirmed by urine test. This study proposes that the clinical criteria for childhood cerebral palsy should be rigorously respected; neuroimaging studies, particularly MRI, should be conducted to confirm the diagnosis, especially in atypical cases.

Late neuropsychological and behavioural outcome of children surgically treated for craniopharyngioma.

Late outcome in 12 children treated by radical surgery for craniopharyngioma is presented. None of the patients presented underwent fractionated traditional or stereotactic radiotherapy. The results show no neurological (except visual dysfunction in 6 subjects), cognitive or short-term memory deficits. Three children were found to have a minor attention deficit. In 5 cases "frontal lobe" malfunctioning was disclosed, and in 5 there were bursts of unpredictable anger. Three children showed worsening of functioning at school: a combination of various causes is suggested to explain the worsening of academic performances. The size of the sample calls for a careful evaluation of results, with due consideration for the influence of various factors on outcome. Multicentre studies are required to increase the sample size and achieve more general conclusions.

Congenital muscular dystrophy with merosin deficiency: MRI findings in five patients.

We present the MRI findings in five patients with congenital muscular dystrophy (CMD) and merosin (laminin alpha2) deficiency, which was total in one and partial in four. In one patient with partial merosin deficiency, MRI was normal. The other four patients had supratentorial white matter abnormalities. In three, T2-weighted images revealed subcortical, deep lobar and periventricular high signal in white matter, while in the other there were only small peritrigonal areas of increased signal. On T1-weighted images, there was slightly low signal. Cortical abnormalities were absent. None of these changes were accompanied by symptoms or signs of central nervous system involvement. White matter abnormalities in a patient with CMD should prompt investigation of merosin.

Radiosurgery for cerebral AVMs in children and adolescents: the neurobehavioral outcome.

Eight patients, ranging in age from 9 to 18 years, were treated for arteriovenous malformations using gamma knife radiosurgery and were evaluated an average of 6 years after treatment to record potential effects of radiosurgery on cognitive and neuropsychological performance. Tests for general intelligence, nonverbal intelligence, memory and its components, and attention performance were administered to patients and compared with test results of age-matched siblings or first cousins. No statistically significant difference was found between the performance of patients and controls in any of the tests administered. Additionally, a specially designed questionnaire completed by the patients, their parents, and their teachers revealed that the patients' emotional and relational behavior was stable and unchanged after treatment. No correlation was found between the neurocognitive test performance and the lesion volumes irradiated, but the lesion site was found to contribute to the type of deficit recorded after treatment. The less invasive nature of the radiosurgical approach, combined with the brevity or absence of hospitalization, presumably contributed to the patients successful physical, mental, and emotional recovery.

Intelligence outcome in children with shunted hydrocephalus of different etiology.

Children with shunted hydrocephalus of differing etiologies were assessed. There was a more selective loss of non-verbal than of verbal intelligence. The verbal and visuo-perceptual abilities were affected by different sets of variables. Variables related to the hydrocephalus had no effects, while associated supratentorial malformations significantly affected non-verbal functions.

Hemispheric specialization in children with unilateral epileptic focus, with and without computed tomography-demonstrated lesion.

We evaluated 24 testable children with unilateral epileptic foci, with and without radiologically demonstrable lesions, to determine if the normal pattern of cerebral dominance is changed by the presence of an epileptic focus. Verbal and figural stimuli were presented tachistoscopically to the right and left visual hemifields to investigate the specific abilities of the two hemispheres. Three blocks of stimuli consisting of two-letter patterns, three-letter patterns, and meaningful two-syllable words were used as verbal stimuli to assess the abilities of the left hemisphere. A test consisting of localizing a dot on a 3 x 3 matrix was used to assess the abilities of the right hemisphere. Six normal children were chosen as controls. In all groups, specialization of the epileptic hemisphere was lost. The presence or absence of a radiologically demonstrable lesion did not influence this pattern.

Combined treatment modality for medulloblastoma in childhood: effects on neuropsychological functioning.

8 long-surviving children, treated for medulloblastoma with combination radiotherapy and chemotherapy after surgery were examined in order to assess general intelligence, immediate attention and prolonged attention. Their siblings or first cousins were selected as controls. The children with medulloblastoma performed significantly worse than their peers, both in intelligence tests and attention tests. A trend towards a positive correlation between age at the start of treatment and IQs was confirmed in our study, while there was no evidence of a correlation between IQs and time elapsed from therapy. The role of chemotherapy, radiotherapy and their combination effect in producing neuropsychological sequelae is discussed.

Impairment of neuropsychological functions in children with medulloblastomas and astrocytomas in the posterior fossa.

Neuropsychological impairment after removal of posterior fossa tumors is a recurrent issue in child neuropsychology and neurosurgery. The aim of this study was to assess verbal and performance intelligence, as well as immediate and sustained attention, in children with medulloblastoma or astrocytoma operated on for total removal of the lesion. Surgical treatment of medulloblastoma was always followed by chemoradiotherapy. Siblings of both tumor groups (without a history of neurological disease, even suspected) were examined as controls. The results were as follows: the cognitive performances were significantly poorer than the controls in both groups; the children with medulloblastoma scored below normal. Attention deficits were present in both groups as well when the usual clinical tests were used. When assessed by means of computerized methodology, the same function was normal. Considering that both groups of children underwent the same surgical treatment and all had hydrocephalus, the severe intellectual impairment reported only in patients with medulloblastoma can be ascribed to chemoradiotherapy. In contrast, the attention deficits present in both groups could be ascribed to the proximity of lesions to the ascending activating system. Malfunctioning of the activating system seems to be bypassed by the computerized administration of stimuli, which supplies motivation and kindles attention.

Development of hemisphere specialization for spatial skills in children from six to twelve years of age.

208 children, male and female, aged 6 to 12 years, grouped in 6-month steps, were tested for three spatial skills: two basic abilities, recognition of two lines of differing slope and of one line of differing slope in a frame and with no frame, and one more complex skill, route-finding by means of maps. The results support the hypotheses of neuropsychological development according to which the hemisphere strategies used in the course of cognitive development for the handling of spatial tasks differ by sex and may change before and after the age of ten.