Electroclinical phenotype in Rubinstein-Taybi syndrome

Thyrotoxic Myopathy with Nonspecific Ophthalmopathy in a Two-Year-Old Child: Case Report and Literature Review

Background: Myopathies encompass a wide range of diseases with diverse etiologies, courses, and prognoses, and can be either genetic or acquired in nature. One of the rare causes of acquired myopathies in children is hyperthyroidism. Ocular manifestations of hyperthyroidism include proptosis (exophthalmos) and widening of the palpebral fissure. Conversely, ptosis may indicate co-existing myasthenia or primary or secondary myopathy. Methods: This study presents a case of a 2-year-old child exhibiting both ocular disorders-each in one eye-along with features of proximal myopathy associated with undiagnosed thyrotoxicosis. Results: To our knowledge, this unique presentation of thyrotoxicosis in a young child has not been previously reported. After appropriate treatment for thyrotoxicosis, the child's ocular and muscular symptoms showed improvement. Conclusions: Given that thyroid disorders can be a rare cause of both myopathy and ocular disorders in children, it is recommended that any child presenting with such symptoms undergo thyroid function screening tests.

Diagnosis and management in Rubinstein-Taybi syndrome: first international consensus statement

Rubinstein-Taybi syndrome (RTS) is an archetypical genetic syndrome that is characterised by intellectual disability, well-defined facial features, distal limb anomalies and atypical growth, among numerous other signs and symptoms. It is caused by variants in either of two genes (CREBBP, EP300) which encode for the proteins CBP and p300, which both have a function in transcription regulation and histone acetylation. As a group of international experts and national support groups dedicated to the syndrome, we realised that marked heterogeneity currently exists in clinical and molecular diagnostic approaches and care practices in various parts of the world. Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria for types of RTS (RTS1: CREBBP; RTS2: EP300), molecular investigations, long-term management of various particular physical and behavioural issues and care planning. The recommendations as presented here will need to be evaluated for improvements to allow for continued optimisation of diagnostics and care.

Genotype and phenotype characteristics of West syndrome in 20 Vietnamese children: Two novel variants detected by next-generation sequencing

BACKGROUND

In children with West syndrome (WS), whose treatment is challenging due to drug resistance and poor prognosis, investigation of genetic etiology and genotype-phenotype characteristics might assist in treatment optimization and genetic counseling.

OBJECTIVE

In this study, we aimed to present the results of genetic analysis and the corresponding phenotypes in a cohort of twenty children with WS in Vietnam.

METHODS

Our study was designed as a single-institution retrospective case series, in which consecutive sampling was used to select WS children having undergone genetic testing. Identified variants were investigated individually or as a variant combination by bioinformatics platforms. Clinical data were used to establish the genotype-phenotype correlation and compare clinical characteristics between groups of genetic causes and unknown causes.

RESULTS

Genetic testing identified at least one variant in 17/20 children. According to ACMG 2015, of all variants, one variant (3.9%) was classified as a benign variant, 16 variants (61.5%) were variants of uncertain significance, 4 (15.4%) were likely pathogenic variants, and 5 (19.2%) were pathogenic variants. These 26 variants belonged to 21 genes, of which eight candidate genes were CREBBP, MED25, HDAC8, SCN3A, ABCD1, TSC2, COL4A1, and NDUFA10. Two novel variants of SCN3A and TSC2 were found. Predicted pathogenic variant combinations were identified in two cases. Compared to three children of unknown etiology, five children with genetic causes had a higher rate of abnormal brain structures, developmental delay, and treatment resistance.

CONCLUSIONS

WS has a genetically heterogeneous etiology, and some cases might be polygenically susceptible. Our findings expand the disease's genotype-phenotype spectrum and support previous literature results that genetic etiology poses an unfavorable outcome in WS.

The behavioral phenotype of Rubinstein-Taybi syndrome: A scoping review of the literature

Rubinstein-Taybi syndrome (RTS) is a rare genetic syndrome associated with growth delay, phenotypic facial characteristics, microcephaly, developmental delay, broad thumbs, and big toes. Most research on RTS has focused on the genotype and physical phenotype; however, several studies have described behavioral, cognitive, social, and emotional characteristics, elucidating the behavioral phenotype of RTS. The reporting of this review was informed by PRISMA guidelines. A systematic search of CINAHL, Medline, and PsychINFO was carried out in March 2021 to identify group studies describing behavioral, cognitive, emotional, psychiatric, and social characteristics in RTS. The studies were quality appraised. Characteristics reported include repetitive behavior, behaviors that challenge, intellectual disability, mental health difficulties, autism characteristics, and heightened sociability. Findings were largely consistent across studies, indicating that many characteristics are likely to form part of the behavioral phenotype of RTS. However, methodological limitations, such as a lack of appropriate comparison groups and inconsistency in measurement weaken these conclusions. There is a need for multi-disciplinary studies, combining genetic and psychological measurement expertise within single research studies. Recommendations are made for future research studies in RTS.

Rubinstein-Taybi Syndrome: A Model of Epigenetic Disorder

The Rubinstein-Taybi syndrome (RSTS) is a rare congenital developmental disorder characterized by a typical facial dysmorphism, distal limb abnormalities, intellectual disability, and many additional phenotypical features. It occurs at between 1/100,000 and 1/125,000 births. Two genes are currently known to cause RSTS, CREBBP and EP300, mutated in around 55% and 8% of clinically diagnosed cases, respectively. To date, 500 pathogenic variants have been reported for the CREBBP gene and 118 for EP300. These two genes encode paralogs acting as lysine acetyltransferase involved in transcriptional regulation and chromatin remodeling with a key role in neuronal plasticity and cognition. Because of the clinical heterogeneity of this syndrome ranging from the typical clinical diagnosis to features overlapping with other Mendelian disorders of the epigenetic machinery, phenotype/genotype correlations remain difficult to establish. In this context, the deciphering of the patho-physiological process underlying these diseases and the definition of a specific episignature will likely improve the diagnostic efficiency but also open novel therapeutic perspectives. This review summarizes the current clinical and molecular knowledge and highlights the epigenetic regulation of RSTS as a model of chromatinopathy.

Rubinstein-Taybi syndrome: New neuroradiological and neuropsychiatric insights from a multidisciplinary approach

Rubinstein-Taybi syndrome is a rare, autosomal dominant, plurimalformative disorder that is clinically characterized by intellectual disability and a wide spectrum of congenital anomalies; facial dysmorphisms are typical, and broad thumbs and great toes are particularly distinctive. Its genetic basis is only partially known, with a detection rate of approximately 65-70%; specifically, microdeletions or mutations in the CREBBP or EP300 genes can be found. Much is known about its clinical features and health-care protocols, but some areas of clinical knowledge are currently unsolved. In particular, few efforts have been made until now to understand the variability in the neuropsychological and neurobehavioral profile and to deepen knowledge of the neuroradiological malformative pattern. Consequently, little is known about the possible genotype-phenotype correlations of these issues. Here, we report clinical and genetic data from a cohort of 23 RSTS Italian patients. The most common features in brain magnetic resonance imaging (MRI) were dysmorphic aspects of the corpus callosum (73.6%) with or without minor dysmorphisms of cerebellar vermis, periventricular posterior white matter hyperintensity, and other less common anomalies. The most interesting feature on the whole spine MRI scans was the tendency for a low-lying conus medullaris without terminal filum thickening. These data will help to improve neuropsychiatric and neuroradiological knowledge and highlight specific genotype-phenotype correlations.

Prospective longitudinal overnight video-EEG evaluation in Phelan-McDermid Syndrome

OBJECTIVE

Phelan-McDermid Syndrome (PMS) is a rare genetic condition associated with loss of function mutations, including deletions, in the chromosome 22q13 region. This PMS phenotype includes intellectual disability, often minimal to absent verbal skills, and other neurologic features including autism spectrum disorder and seizures. Reports indicate seizures and abnormal electroencephalograms (EEGs) in this population, but previous studies do not describe EEG findings during sleep or prognostic value of abnormal EEG over any time period.

METHODS

During a natural history study, 16 consecutively enrolled participants (mean age 10years) with PMS underwent both routine (approximately 25min) and overnight (average 9.65h) video-EEG, in addition to genetic testing, neurodevelopmental assessment, neurological examination, and epilepsy phenotyping. Over 240h of EEG, data was recorded. Comparison of findings from the routine EEG was made with prolonged EEG acquired during awake and sleep the same night. In a subset of nine participants, the overnight EEG was repeated one or more years later to observe the natural evolution and prognostic value of any abnormalities noted at baseline.

RESULTS

A history of epilepsy, with multiple seizure types, was confirmed in seven of the 16 participants, giving a prevalence of 43.8% in this cohort. All but one EEG was abnormal (15 of 16), and 75% (12 of 16) showed epileptiform activity. Of these, only 25% of participants (3 of 12) showed definitive epileptiform discharges during the routine study. Overnight EEGs (sleep included) did not show any clinical events consistent with seizures or electrophic seizures, however, overnight EEG showed either more frequent and/or more definitive epileptiform activity in 68.75% (11 of 16) participants. All seven of the 16 participants who had previously been diagnosed with epilepsy showed epileptiform abnormalities. In addition to a wide range of epileptiform activity observed, generalized slowing with poor background organization was frequently noted. Follow-up EEG confirmed persistence of abnormal discharges, but none of the abnormal EEGs showed evolution to electrographic seizures. Clinically, there was no emergence of epilepsy or significant developmental regression noted in the time frame observed.

CONCLUSIONS

This is the first and most abundant prolonged awake and sleep video-EEG data recorded in a PMS cohort to date. The importance of overnight prolonged EEGs is highlighted by findings from this study, as they can be used to document the varied topographies of EEG abnormalities in conditions such as PMS, which are often missed during routine EEG studies. While the long-term significance of the EEG abnormalities found (beyond 1year) remains uncertain despite their persistence over time, these findings do underscore the current clinical recommendation that overnight prolonged EEG studies (with sleep) should be conducted in individuals with PMS.