Appropriateness of array-CGH in the ADHD clinics: A comparative study.

Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorder with a worldwide prevalence of about 5%. The disorder is characterized by inattentive, hyperactive and impulsive behavior and is often comorbid with other neuropsychiatric conditions. Array comparative genomic hybridization (array-CGH) testing has been proved to be useful to detect chromosomal aberrations in several neuropsychiatric conditions including autism spectrum disorders (ASD) and intellectual disability (ID). The usefulness of array-CGH in the ADHD clinics is still debated and no conclusive evidence has been reached to date. We performed array-CGH in 98 children and adolescents divided in two similarly sized groups according to the clinical diagnosis: (a) one group diagnosed with ADHD as primary diagnosis; (b) the other group in which ADHD was co-morbid with ASD and/or ID. We detected pathogenetic and likely pathogenetic copy number variants (CNVs) in 12% subjects in which ADHD was co-morbid with autism and/or intellectual disability and in 8.5% subjects diagnosed with ADHD as primary diagnosis. Detection of CNVs of unknown clinical significance was similar in the two groups being 27% and 32%, respectively. Benign and likely benign CNVs accounted for 61% and 59.5% in the first and second group, respectively. Differences in the diagnostic yield were not statistically significant between the two groups (P > .05). Our data strongly suggest that array-CGH (a) is a valuable diagnostic tool to detect clinically significant CNVs in individuals with ADHD even in the absence of comorbidity with ASD and/or ID and (b) should be implemented routinely in the ADHD clinics.

Xp22.33p22.12 Duplication in a Patient with Intellectual Disability and Dysmorphic Facial Features.

A novel 19.98-Mb duplication in chromosome Xp22.33p22.12 was detected by array CGH in a 30-year-old man affected by intellectual disability, congenital hypotonia and dysmorphic features. The duplication encompasses more than 100 known genes. Many of these genes (such as neuroligin 4, cyclin-dependent kinase like 5, and others) have already correlated with X-linked intellectual disability and/or neurodevelopmental disorders. Due to the high number of potentially pathogenic genes involved in the reported duplication, we cannot correlate the clinical phenotype to a single gene. Indeed, we suggest that the resulting clinical phenotype may have arisen from the overexpression and consequent perturbation of fine gene dosage.

Intractable seizures in tuberous sclerosis complex: from molecular pathogenesis to the rationale for treatment.

Tuberous sclerosis complex is a multisystem autosomal dominant genetic disorder resulting from mutations in one of two genes, TSC1 and TSC2. Pathologically, tuberous sclerosis complex is characterized by abnormal cellular differentiation and proliferation, as well as abnormal neuronal migration. Epilepsy occurs in about 90% of patients, with onset frequently in the first year of life. In a sizable proportion of individuals, seizures tend to be refractory to antiepileptic drug treatment. This article reviews the progress in understanding drug-resistant seizures in tuberous sclerosis complex, from molecular pathogenesis to the pathophysiologic mechanisms of epileptogenesis, and the rationale for appropriate medical and surgical treatment.

Epilepsy surgery for tuberous sclerosis.

Tuberous sclerosis complex is often associated with medically refractory epilepsy secondary to cortical tubers. Previous studies have identified an association between early seizure onset, greater seizure burden, and mental retardation in childhood. Early effective seizure control could therefore significantly reduce the adverse developmental effects of chronic epilepsy in tuberous sclerosis complex. In medically intractable epileptic patients, surgical treatment has been demonstrated to reduce or abolish seizures and the associated burden for the child and its environment. Epilepsy surgery has not been widely used in patients with tuberous sclerosis complex thus far, mostly because of the concern that the multifocal nature of the cortical lesions could be associated with the development of independent epileptogenic zones. Advances in electroencephalographic techniques, functional neuroimaging, and invasive cortical mapping are changing this view and allowing an increased number of tuberous sclerosis complex patients to be evaluated for resective surgery. Additional techniques emerging in the neurosurgical field may add further treatment options to the current state of the art.

Association between presenilin-1 -48C/T polymorphism and Down's syndrome.

Individuals with Down's syndrome (DS), i.e., trisomy 21, over 40 years of age, are likely to develop neuropathological changes characteristic of Alzheimer's disease (AD). The involvement of chromosome 21 both in DS and AD suggests a shared genetic susceptibility to these disorders, but genetic determinants are still undefined. The -48C/T polymorphism in the PSEN1 promoter is a possible candidate, since it has recently been associated with an increased risk of early onset AD. Based on the assumption that the excess of dementia in DS might be a consequence of a different distribution of the -48C/T polymorphism, we investigated the association between DS and this polymorphism in patients with trisomy 21 and controls. Overall, 260 DS patients and 197 controls were recruited at the Department of Neurosciences, Tor Vergata University of Rome. Cases and controls had similar age and gender distribution. High molecular weight DNA was extracted from whole blood samples collected in EDTANa(2) and -48C/T genotypes were determined. Genotype and allele frequencies were compared between cases and controls. Cases were less likely than controls to have the CC genotype ( P = 0.05). A significant difference for allele distribution between DS cases and controls was found, with DS showing a lower frequency of the allele C compared with the control population (OR: 0.57; 95% CI: 0.35-0.91; P = 0.01). No significant interaction of PSEN1 with age, gender, ApoE and -850 TNF-alpha polymorphisms was found. The association found suggests that the -48C/T polymorphism in the PSN1 gene promoter, which is involved in the modulation of amyloid beta load in human AD, is associated with DS. However, the biological role of this polymorphism in DS-related dementia remains unclear and merits further investigation.

The role of -850 tumor necrosis factor-alpha and apolipoprotein E genetic polymorphism in patients with Down's syndrome-related dementia.

Down's syndrome (DS) is a disease with a complex etiology. It is likely that other factors besides genes located on chromosome 21 may play a role in clinical features of affected patients. Tumor necrosis factor-alpha (TNF-alpha) (6p21.3) and apolipoprotein E (APOE) (19q13.2) are candidate genes as they interact with the brain deposition of Abeta, one of the neuropathological hallmarks in DS. We examined 136 DS patients and 113 controls for -850 TNF-alpha and APOE polymorphisms. The -850T frequency in DS was significantly higher than in controls (P<0.005, OR 2.05, 95% CI 1.22-3.49) while the APOE E4 allele was negatively selected in patients compared to normal subjects (P<0.005, OR 0.38, 95% CI 0.20-0.71). Our findings suggest that the -850T allele, which is more common among patients at high risk of dementia such as those with DS, might eventually play a role in the development of dementia; no inference on the role of the allele APOE E4 in DS-related dementia may be derived from our results.

Tuberous sclerosis complex: a review of neurological aspects.

Tuberous sclerosis complex is characterized by hamartomatous lesions involving skin, brain, kidneys, eyes and heart. Pathologically, tuberous sclerosis is a disorder of cell migration, proliferation and differentiation. Cell lineage and cell migration disorders in the developing cortex of tuberous sclerosis complex patients might produce very different neurological phenotypes including epilepsy, cognitive impairment and autism. Cortical tubers constitute the hallmark of the disease and are pathognomonic of cerebral tuberous sclerosis. Epilepsy is the most common neurological feature, occurring in 96% of patients. Seizures often begin in the first months of life and are frequently severe and intractable. The treatment of seizures has recently benefited from the advent of the new anti-epileptic drugs. Selected drug-resistant patients with tuberous sclerosis complex could be considered for surgical treatment. Clear localization of the most active epileptogenic focus and the zone of the cortical abnormality may lead to tuberectomy and improved seizure control in selective drug-resistant patients. The finding of multiple areas of cerebral involvement should not automatically preclude epilepsy surgery in a child with intractable seizures and a well defined seizure origin.