Susana Boronat

Tuberous sclerosis complex without tubers and subependymal nodules: a phenotype–genotype study

Tuberous sclerosis complex (TSC) is caused by a mutation in the TSC1 or TSC2 genes. However, 15% of patients have no mutation identified. Tubers and subependymal nodules (SENs) are the typical brain lesions in TSC and are present in 90–95% of patients. The objective of this study is to characterize the specific genotype–phenotype of patients without these lesions. We analyzed the features of 11 patients without typical TSC neuroanatomic features. Ten had TSC1/TSC2 mutational analysis, which was negative. Clinically they had lesions thought to be of neural crest (NC) origin, such as hypomelanotic macules, facial angiofibromas, cardiac rhabdomyomas, angiomyolipomas, and lymphangioleiomyomatosis. We hypothesize that patients without tubers and SENs reflect mosaicism caused by a mutation in TSC1 or TSC2 in a NC cell during embryonic development. This may explain the negative results in TSC1 and TSC2 testing in DNA from peripheral leukocytes.

Hippocampal Abnormalities in Magnetic Resonance Imaging (MRI) of 15q Duplication Syndromes

Patients with 15q duplication syndromes, including isodicentric chromosome 15 and interstitial duplications, usually present with autism spectrum disorder, intellectual disability, and frequently epilepsy. Neuroimaging studies in these patients are typically reported as normal, but nonspecific findings such as thinning of the corpus callosum and increased pericerebral spaces have been reported. A review of brain magnetic resonance imaging (MRI) studies of 11 individuals seen at the Massachusetts General Hospital Dup15q Center was performed. Hippocampus morphology was specifically reviewed, as a recent neuropathologic study has found frequent hippocampal heterotopias and dysplasias in these disorders. Two subjects had unilateral hippocampal sclerosis and 6 had bilateral hippocampal malformations. Hypoplasia of the corpus callosum was present in 2 subjects.

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.

Intracranial Arteriopathy in Tuberous Sclerosis Complex

Arterial aneurysms, mostly aortic and intracranial, have been occasionally reported in patients with tuberous sclerosis complex. Brain magnetic resonance imaging reports of 404 patients with definite and 16 patients with either probable or possible tuberous sclerosis complex were revised for intracranial aneurysms. Among these patients, brain images of 220 patients with definite and 16 with probable or possible tuberous sclerosis complex were reviewed. Intracranial aneurysms were reported in 3 of 404 patients with a definite diagnosis (0.74%) (general population: 0.35%), including 2 children. A fourth intracranial aneurysm was found in a patient with probable tuberous sclerosis complex, who did not have tubers or subependymal nodules but had clinical manifestations related to neural crest derivatives, including lymphangioleiomyomatosis and extrarenal angiomyolipomas. The authors hypothesize that neural crest dysfunction can have a major role in intracranial arteriopathy in tuberous sclerosis complex, as smooth muscle cells in the forebrain vessels are of neural crest origin.

Absence of subependymal nodules in patients with tubers suggests possible neuroectodermal mosaicism in tuberous sclerosis complex

Patients with tuberous sclerosis complex (TSC) with brain involvement usually have both tubers and subependymal nodules (SENs) and the occurrence of one lesion without the other seems to be rare. The aim of this study was to assess the specific clinical manifestations and genotype of patients with one type of lesion or the other but not both.

Lymphedema in tuberous sclerosis complex.

Congenital lymphedema has been described as a possible rare association of tuberous sclerosis complex (TSC), with only six previous cases reported in the literature. TSC is an autosomal dominant, multisystem disorder connected to aberrant regulation of the mammalian target of rapamycin (mTOR) pathway. The aim of this study is to review cases of lymphedema in a large cohort of TSC patients. The medical records of 268 patients seen at The Herscot Center for Children and Adults with Tuberous Sclerosis Complex at the Massachusetts General Hospital from 2002 to 2012 were retrospectively reviewed for reports of lymphedema or edema of unknown etiology. Genotypic and phenotypic data were collected in accordance with institutional review board (IRB) approval. This cohort presents two new cases of congenital lymphedema in TSC patients and acquired lymphedema was found in eight additional cases. Thus, we report 10 new cases of lymphedema in TSC (4%). The two patients with congenital lymphedema were female, as were the previous six reported cases. The frequency of lymphedema reported here (4%) is higher than the estimated prevalence in the general population (0.133–0.144%), suggesting a higher frequency of lymphedema in TSC. This study shows that patients with TSC and lymphedema are more likely to be females with renal AMLs and suggests that congenital lymphedema is a gender‐specific (female) manifestation of TSC. Exploration of the potential role of mTOR antagonists may be important in treatment of lymphedema in TSC patients.

Rib and vertebral bone fibrous dysplasia in a child with tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder characterized by benign hamartomas in multiple organ systems, primarily the skin, brain, heart, kidneys, lungs, and eyes. The skeletal system is commonly affected in patients with TSC, but these bone lesions are generally asymptomatic and have not been well characterized. We present clinically significant bone growth in two ribs and vertebrae in an 8‐year‐old male patient with TSC and discuss the effects of mammalian target of rapamycin (mTOR) inhibitors as a possible treatment for these osseous abnormalities. This report suggests that skeletal lesions may hold more clinical significance than previously assumed and that further research should be directed toward understanding bone involvement in TSC.

Cerebellar lesions are associated with TSC2 mutations in tuberous sclerosis complex: a retrospective record review study

Cerebellar lesions are present in approximately 30% of patients with tuberous sclerosis complex. Although several prior studies have characterized these lesions, our study provides the first description of the specific distribution of these lesions within the cerebellum and the first genotype–phenotype correlation yet to be published.

Sclerotic bone lesions at abdominal magnetic resonance imaging in children with tuberous sclerosis complex

BackgroundSclerotic bone lesions are often seen on chest CT in adults with tuberous sclerosis complex.ObjectiveTo characterize bone lesions at abdominal MRI in children with tuberous sclerosis complex.Materials and methodsThis retrospective review included 70 children with tuberous sclerosis complex who had undergone abdominal MRI for renal imaging. An additional longitudinal study was performed in 50 children who had had two or more MRI scans. Abdominal CT (eight children) and radiographs (three children) were reviewed and compared with MRI.ResultsA total of 173 sclerotic bone lesions were detected in 51/70 children (73%; 95% confidence interval: 0.61–0.82) chiefly affecting vertebral pedicles. New lesions appeared in 20 children and growth of previous sclerotic bone lesions was documented in 14 children. Sclerotic bone lesions were more frequent in girls and in children with more extensive renal involvement.ConclusionSclerotic bone lesions are commonly detected by abdominal MRI in children with tuberous sclerosis complex. They usually affect posterior vertebral elements and their number and size increase with age. As current recommendations for tuberous sclerosis complex surveillance include renal MR performed in childhood, recognition of these lesions is useful.

Gastrointestinal problems in 15q duplication syndrome

Chromosome 15q duplication syndrome (Dup15q syndrome) is a neurodevelopmental disorder involving copy number gains of the maternal chromosome 15q11.2-q13 region, characterized by intellectual disability, developmental delay, autism spectrum disorder (ASD), and epilepsy. Gastrointestinal (GI) problems in Dup15q syndrome have been reported only rarely, mostly focused on neonatal feeding difficulties. A retrospective review of the medical records of 46 patients with Dup15q syndrome was conducted to assess GI issues and their treatments in this population. GI symptoms were present in 76.7% of subjects with an isodicentric duplication and 87.5% with an interstitial duplication. There was no clear association between GI issues and ASD, with symptoms occurring in 78.9% of all subjects and 78.2% of ASD subjects. The most commonly reported symptoms were gastroesophageal reflux (56.7%) and constipation (60%), with 30% of subjects reporting both. The most common treatments were polyethylene glycol for constipation and proton pump inhibitors for reflux. Behaviors such as irritability and aggressiveness improved with treatment of GI symptoms in several subjects. The results indicate that GI symptoms are common in Dup15q syndrome and may have an atypical presentation. Diagnosis may be difficult, especially in individuals who are nonverbal or minimally verbal, so increased awareness is critical for early diagnosis and treatment.