Agnies M. van Eeghen

Understanding relationships between autism, intelligence, and epilepsy: a cross-disorder approach

Aim  As relationships between autistic traits, epilepsy, and cognitive functioning remain poorly understood, these associations were explored in the biologically related disorders tuberous sclerosis complex (TSC), neurofibromatosis type 1 (NF1), and epilepsy.

Genotype and cognitive phenotype of patients with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant, multisystem disorder, which affects 1 in 6000 people. About half of these patients are affected by mental retardation, which has been associated with TSC2 mutations, epilepsy severity and tuber burden. The bimodal intelligence distribution in TSC populations suggests the existence of subgroups with distinct pathophysiologies, which remain to be identified. Furthermore, it is unknown if heterozygous germline mutations in TSC2 can produce the neurocognitive phenotype of TSC independent of epilepsy and tubers. Genotype–phenotype correlations may help to determine risk profiles and select patients for targeted treatments. A retrospective chart review was performed, including a large cohort of 137 TSC patients who received intelligence assessment and genetic mutation analysis. The distribution of intellectual outcomes was investigated for selected genotypes. Genotype–neurocognitive phenotype correlations were performed and associations between specific germline mutations and intellectual outcomes were compared. Results showed that TSC1 mutations in the tuberin interaction domain were significantly associated with lower intellectual outcomes (P<0.03), which was also the case for TSC2 protein-truncating and hamartin interaction domain mutations (both P<0.05). TSC2 missense mutations and small in-frame deletions were significantly associated with higher IQ/DQs (P<0.05). Effects related to the mutation location within the TSC2 gene were found. These findings suggest that TSC2 protein-truncating mutations and small in-frame mutations are associated with distinctly different intelligence profiles, providing further evidence that different types and locations of TSC germline mutations may be associated with distinct neurocognitive phenotypes.

Functional Assessment of TSC2 Variants Identified in Individuals with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in the TSC1 or TSC2 genes. The TSC1 and TSC2 gene products, TSC1 and TSC2, form a complex that inhibits the mammalian target of rapamycin (mTOR) complex 1 (TORC1). Here, we investigate the effects of 78 TSC2 variants identified in individuals suspected of TSC, on the function of the TSC1–TSC2 complex. According to our functional assessment, 40 variants disrupted the TSC1–TSC2‐dependent inhibition of TORC1. We classified 34 of these as pathogenic, three as probably pathogenic and three as possibly pathogenic. In one case, a likely effect on splicing as well as an effect on function was noted. In 15 cases, our functional assessment did not agree with the predictions of the SIFT amino acid substitution analysis software. Our data support the notion that different, nonterminating TSC2 mutations can have distinct effects on TSC1–TSC2 function, and therefore, on TSC pathology.

The neuroanatomical phenotype of tuberous sclerosis complex: focus on radial migration lines

IntroductionThe contribution of radial migration lines (RMLs) to the neuroanatomical and neurocognitive phenotype of tuberous sclerosis complex (TSC) is unclear. The aim of this study was to perform a comprehensive evaluation of the neuroradiological phenotype of TSC, distinguishing RMLs from normal-appearing white matter (NAWM) using diffusion tensor imaging (DTI) and volumetric fluid-attenuated inversion recovery imaging.MethodsMagnetic resonance images of 30 patients with TSC were evaluated. The frequencies of RMLs, tubers, and subependymal nodules (SENs) were determined for every hemispheric lobe. Cerebellar lesions and subependymal giant cell tumors were counted. DTI metrics were obtained from the NAWM of every hemispheric lobe and from the largest RML and tuber. Analyses of variance and correlations were performed to investigate the associations between neuroanatomical characteristics and relationships between RML frequency and neurocognitive outcomes. NAWM DTI metrics were compared with measurements of 16 control patients.ResultsA mean of 47 RMLs, 27 tubers, and 10 SENs were found per patient, and the frequencies of these lesions were strongly correlated (p < 0.001). RML fractional anisotropy and mean diffusivity were strongly inversely correlated (p = 0.003). NAWM DTI metrics were similar to the controls (p = 0.26). RML frequency was strongly associated with age of seizure onset (p = 0.003), intelligence outcomes (p = 0.01), and level of autistic features (p = 0.007).ConclusionA detailed neuroradiological phenotype is presented, showing that RMLs are the most frequent neuroanatomical lesion, are responsible for white matter DTI abnormalities, and are strongly associated with age of seizure onset, intelligence outcomes, and level of autistic features.

Central TSC2 missense mutations are associated with a reduced risk of infantile spasms

Tuberous sclerosis complex (TSC) is an autosomal dominant syndrome with a variable neurocognitive phenotype. Recently, different intelligence profiles were observed for distinct mutation types and locations, suggesting that individuals with missense mutations represent a subgroup with milder neurocognitive outcomes. We applied these recent insights to the analysis of the epilepsy phenotype in a large cohort of patients with TSC. Associations between genotype and a history of epilepsy and/or infantile spasms (IS) were explored retrospectively, using data from 478 TSC patients from the databases of the Tuberous Sclerosis Alliance and the Herscot Center at Massachusetts General Hospital. Absolute and relative risks for IS and other types of epilepsy were calculated for various mutation classes, selected according to type and location. As expected, TSC2 mutations were associated with a significantly higher occurrence of IS and other epilepsy types. However, missense mutations located in the central region of TSC2 (exons 23-33) were associated with a significantly reduced incidence of IS. Our study further delineates the epilepsy phenotype in TSC patients. Identifying distinct epilepsy phenotypes for specific mutation subgroups may help identify relevant biomarkers and assist clinicians in making treatment decisions.

Characterizing sleep disorders of adults with tuberous sclerosis complex: A questionnaire-based study and review

An adult cohort with tuberous sclerosis complex was investigated for the prevalence of sleep disturbances and the relationship with seizure variables, medication, and psychological functioning. Information on 35 adults was gathered using four questionnaires: Epworth Sleepiness Scale (ESS), Sleep and Epilepsy Questionnaire (SEQ), Sleep Diagnosis List (SDL), and Adult Self-Report Scale (ASR). In addition, clinical, genetic and electrophysiological data were collected. Of 35 respondents, 25 had a history of epilepsy. A subjective sleep disorder was found in 31% of the cohort. Insomnia scores showed a significant positive correlation with obstructive sleep apnea syndrome and restless legs syndrome scores. Significant correlations were found between daytime sleepiness and scores on depression, antisocial behavior, and use of mental health medication. A subgroup using antiepileptic medication showed high correlations between daytime sleepiness, attention deficits, and anxiety scores.

Cognitive and adaptive development of patients with tuberous sclerosis complex: A retrospective, longitudinal investigation

OBJECTIVE The aim of the work described here was to systematically analyze the developmental trajectory of patients with tuberous sclerosis complex (TSC). METHODS A retrospective longitudinal chart review was performed, selecting patients who received multiple neuropsychological assessments. Intellectual/Developmental Quotients, Adaptive Behavior Composite scores, and clinical data were collected. On available EEGs, interictal epileptiform discharges were counted. RESULTS Sixty-six (18%) patients with TSC received multiple cognitive and adaptive development assessments. The mean intelligence of this study group remained relatively stable, albeit variable. Significant decline in adaptive functioning was observed, associated with lower age at seizure onset. Patients who underwent neurosurgery prior to baseline testing showed cognitive improvement. Developmental declines were significantly associated with increased numbers of antiepileptic drugs, with a trend toward association with mutation type and interictal epileptiform discharges. CONCLUSION This study suggests that the developmental course of patients with TSC may be altered by epilepsy comorbidity and neurosurgery, underlining the need for early and effective interventions in this population.

Arachnoid cysts in tuberous sclerosis complex

OBJECTIVE Some clinical findings in tuberous sclerosis complex (TSC), such as hypomelanotic macules or angiofibromas are related to problems in development of the neural crest, which is also the origin of cranial leptomeninges. Arachnoid cysts have been reported in two TSC patients to date. The purpose of this study was to assess the prevalence and characteristics of arachnoid cysts in a large cohort of TSC. MATERIALS AND METHOD We performed a review of brain MRIs of 220 TSC patients searching for arachnoid cysts. RESULTS Arachnoid cysts were found in 12 (5.5%) (general population: 0.5%), including ten males (83.3%). Four patients (33.3%) had also autosomal dominant polycystic kidney disease (ADPKD) due to a contiguous deletion of the TSC2-PKD1 genes. Three patients (25%) had two or more arachnoid cysts, of whom two also had ADPKD. One patient with an arachnoid cyst did not have tubers, subependymal nodules or white matter migration lines. CONCLUSION Our study suggests that arachnoid cysts are part of the clinical spectrum of TSC and may be also present in TSC patients without other typical TSC brain lesions.

Clobazam therapy of refractory epilepsy in tuberous sclerosis complex

Clobazam (CLB) was recently approved by the FDA, but has not been evaluated in tuberous sclerosis complex (TSC). We retrospectively reviewed a cohort of patients with TSC and refractory epilepsy who started CLB over a 5-year period. Clinical characteristics and number of tubers on MRI were assessed. Duration of therapy, therapeutic response and adverse events were recorded. CLB was prescribed in 29 adults and children of whom 72% were cognitively impaired, with a median age at seizure onset of 5 months. Mean duration of CLB therapy was 17.3 months with a 12 and 24-month estimated retention rate of 82% and 68%, respectively. Twenty patients (69%) reported a good response (>50% seizure reduction) at the end of the titration, and six patients (21%) remained good responders after 12 months of CLB therapy. Adverse events occurred in 13 patients, predominantly somnolence and behavioral disorders. One quarter of the responders reported improvement in behavior. No predictive factor for a good response could be identified. CLB appears to be a well-tolerated and valuable option for treatment of refractory epilepsy in TSC.

Tuberous sclerosis complex: Concerns and needs of patients and parents from the transitional period to adulthood

INTRODUCTION Transitioning into adulthood and from pediatric services to adult healthcare are both challenging processes for young adults with rare chronic disorders such as tuberous sclerosis complex (TSC) and their parents. Adult healthcare systems are often less family-oriented and lack multidisciplinary care and experience with TSC, which can result in increased health risks and morbidity. Patient-driven data on care needs are necessary to optimize support for this vulnerable patient group. AIM The aim of this study was to explore the concerns and care needs of young adult patients with TSC in medical, psychological, and socioeconomical domains. METHOD A qualitative study was performed using semistructured interviews with 16 patients (median age: 21years; range: 17 to 30) and 12 parents. Concerns and care needs were organized using the International Classification of Functioning, Disability, and Health (ICF). RESULTS Main concerns involved mental and physical health, participation, self-management skills, family planning, and side effects of medications. Patients expressed the need for multidisciplinary care that is well-informed, easily accessible, and focused on the patient as a whole, including his/her family. Parents reported high stress levels. CONCLUSION The current study provides patient-driven information, allowing recommendations to facilitate the (transition of) care for young adults with TSC. In addition to seizures, tumor growth, and TSC-associated neuropsychiatric disorders (TAND), more attention is needed for concerns and care needs specific to the transitional period, participation, and environmental factors. Adult healthcare providers should offer expert multidisciplinary care for adult patients with TSC, including attention for parental stress.