Genetic and clinical characteristics of 24 mainland Chinese patients with CTNNB1 loss-of-function variants

Clinical phenotypic spectrum of CTNNB1 neurodevelopmental disorder

Pathogenic heterozygous loss of function variants in CTNNB1 are associated with CTNNB1 neurodevelopmental disorder. We report the clinical phenotype of individuals with CTNNB1 neurodevelopmental disorder using both caregiver-reported data (medical history, adaptive function, quality of life, and behavior issues) and in-person clinical assessments (neurological, motor, and cognitive function) in 32 individuals with likely pathogenic or pathogenic CTNNB1 variants. Most individuals had truncal hypotonia, muscle weakness, hypertonia, dystonia, microcephaly, and many had a history of tethered cord. Visual problems included strabismus, hyperopia, and familial exudative vitreoretinopathy. Half of individuals walked without an assistive device. The mean Gross Motor Functional Measure-66 score was 56.6 (SD = 14.8). Average time to complete Nine-Hole Peg Test was slower than norms. Mean general conceptual ability composite scores from Differential Ability Scales Second Edition were very low (M = 58.3, SD = 11.3). Fifty-five percent of individuals had low adaptive functioning based on the Vineland Adaptive Behavioral Scales. Based upon the Child Behavior Checklist total problems score, the majority (65%) of individuals had behavioral challenges. The mean overall Quality of Life Inventory-Disability score was 81.7 (SD = 11.9). These data provide a detailed characterization of clinical features in individuals with CTNNB1 neurodevelopmental disorder.

Neurodegeneration-associated protein VAPB regulates proliferation in medulloblastoma

VAMP (Vesicle-associated membrane protein)-associated protein B and C (VAPB) has been widely studied in neurodegenerative diseases such as ALS, but little is known about its role in cancer. Medulloblastoma is a common brain malignancy in children and arises from undifferentiated cells during neuronal development. Therefore, medulloblastoma is an interesting model to investigate the possible relationship between VAPB and tumorigenesis. Here we demonstrate that high VAPB expression in medulloblastoma correlates with decreased overall patient survival. Consistent with this clinical correlation, we find that VAPB is required for normal proliferation rates of medulloblastoma cells in vitro and in vivo. Knockout of VAPB (VAPBKO) delayed cell cycle progression. Furthermore, transcript levels of WNT-related proteins were decreased in the VAPBKO. We conclude that VAPB is required for proliferation of medulloblastoma cells, thus revealing VAPB as a potential therapeutic target for medulloblastoma treatment.

Alopecia areata-like pattern of baldness: the most recent update and the expansion of novel phenotype and genotype in the CTNNB1 gene

Neurodevelopmental disorder with spastic diplegia and visual defects (NEDSDV) is a rare autosomal dominant genetic disorder caused by genetic alterations in the CTNNB1 gene. CTNNB1 is a gene that encodes β-catenin, an effector protein in the canonical Wnt pathway involved in stem cell differentiation and proliferation, synaptogenesis, and a wide range of essential cellular mechanisms. Mutations in this gene are also found in specific malignancies as well as exudative vitreoretinopathy. To date, only a limited number of cases of this disease have been reported, and though they share some phenotypic manifestations such as intellectual disability, developmental delay, microcephaly, behavioral abnormalities, and dystonia, the variety of phenotypic traits of these patients shows extreme heterogeneity. In this study, two cases of NEDSDV with de novo CTNNB1 mutations: c.1420C>T(p.R474X) and c.1377_1378Del(p.Ala460Serfs*29), found with whole exome sequencing (WES) have been reported and the clinical and paraclinical characteristics of these patients have been described. Due to such a wide range of clinical characteristics, the identification of new patients and novel variants is of great importance in order to establish a more complete phenotypic spectrum, as well as to conclude the genotype-phenotype correlations in these cases.

Congenital heart defects in CTNNB1 syndrome: Raising clinical awareness

CTNNB1 [OMIM *116806] encodes β-catenin, an integral part of the cadherin/catenin complex, which functions as effector of Wnt signaling. CTNNB1 is highly expressed in brain as well as in other tissues, including heart. Heterozygous CTNNB1 pathogenic variations are associated with a neurodevelopmental disorder characterized by spastic diplegia and visual defects (NEDSDV) [OMIM #615075], featuring psychomotor delay, intellectual disability, behavioral disturbances, movement disorders, visual defects and subtle facial and somatic features. We report on a new series of 19 NEDSDV patients (mean age 10.3 years), nine of whom bearing novel CTNNB1 variants. Notably, five patients showed congenital heart anomalies including absent pulmonary valve with intact ventricular septum, atrioventricular canal with hypoplastic aortic arch, tetralogy of Fallot, and mitral valve prolapse. We focused on the cardiac phenotype characterizing such cases and reviewed the congenital heart defects in previously reported NEDSDV patients. While congenital heart defects had occasionally been reported so far, the present findings configure a higher rate of cardiac anomalies, suggesting dedicated heart examination to NEDSDV clinical management.

Molecular Subtype Classification of Postmenopausal Osteoporosis and Immune Infiltration Microenvironment Based on Bioinformatics Analysis of Osteoclast-Regulatory Genes

Osteoporosis is common in postmenopausal women but is often asymptomatic until a fracture occurs, highlighting the importance of early screening and preventive interventions. This study aimed to develop molecular subtype risk stratification of postmenopausal osteoporosis and analyze the immune infiltration microenvironment. Microarray data for osteoporosis were downloaded and analyzed. Logistic and least absolute shrinkage and selection operator (LASSO) regression analyses were used to construct the molecular risk model. Circulating blood samples were collected from 10 enrolled participants to validate the key differentially expressed genes, and consistent clustering based on the expression profiles of candidate genes was performed to obtain molecular subtypes. Three key genes, CTNNB1, MITF, and TNFSF11, were obtained as variables and used to construct the risk model. External experimental validation showed substantial differences in the three key genes between patients with osteoporosis and the controls (p < 0.05). Three subtypes were obtained based on dimensionality reduction clustering results. Cluster 3 had significantly more patients with low bone mineral density (BMD), whereas Cluster 2 had significantly more patients with high BMD (p < 0.05). This study introduced a novel molecular risk model and subtype classification system, which is an evidence-based screening strategy that will guide the active prevention, early diagnosis, and treatment of osteoporosis in high-risk postmenopausal women.

From Feeding Challenges to Oral-Motor Dyspraxia: A Comprehensive Description of 10 New Cases with CTNNB1 Syndrome

CTNNB1 syndrome is an autosomal-dominant neurodevelopmental disorder featuring developmental delay; intellectual disability; behavioral disturbances; movement disorders; visual defects; and subtle facial features caused by de novo loss-of-function variants in the CTNNB1 gene. Due to paucity of data, this study intends to describe feeding issues and oral-motor dyspraxia in an unselected cohort of 10 patients with a confirmed molecular diagnosis. Pathogenic variants along with key information regarding oral-motor features were collected. Sialorrhea was quantified using the Drooling Quotient 5. Feeding abilities were screened using the Italian version of the Montreal Children's Hospital Feeding Scale (I-MCH-FS). Mild-to-severe coordination difficulties in single or in a sequence of movements involving the endo-oral and peri-oral muscles were noticed across the entire cohort. Mild-to-profuse drooling was a commonly complained-about issue by 30% of parents. The mean total I-MCH-FS t-score equivalent was 43.1 ± 7.5. These findings contribute to the understanding of the CTNNB1 syndrome highlighting the oral motor phenotype, and correlating specific gene variants with clinical characteristics.

CTNNB1-related neurodevelopmental disorder mimics cerebral palsy: case report

While somatic gain-of-function mutations in the CTNNB1 gene cause diverse malignancies, germline loss-of-function mutations cause neurodevelopmental disorders or familial exudative vitreoretinopathy. In particular, CTNNB1-related neurodevelopmental disorders have various phenotypes, and a genotype-phenotype relationship has not been established. We report two patients with CTNNB1-related neurodevelopmental disorder whose clinical features were similar to those of cerebral palsy, hindering diagnosis.

CTNNB1 in neurodevelopmental disorders

CTNNB1 is the gene that encodes β-catenin which acts as a key player in the Wnt signaling pathway and regulates cellular homeostasis. Most CTNNB1-related studies have been mainly focused on its role in cancer. Recently, CTNNB1 has also been found involved in neurodevelopmental disorders (NDDs), such as intellectual disability, autism, and schizophrenia. Mutations of CTNNB1 lead to the dysfunction of the Wnt signaling pathway that regulates gene transcription and further disturbs synaptic plasticity, neuronal apoptosis, and neurogenesis. In this review, we discuss a wide range of aspects of CTNNB1 and its physiological and pathological functions in the brain. We also provide an overview of the most recent research regarding CTNNB1 expression and its function in NDDs. We propose that CTNNB1 would be one of the top high-risk genes for NDDs. It could also be a potential therapeutic target for the treatment of NDDs.

Genetic and clinical characteristics of 24 mainland Chinese patients with CTNNB1 loss-of-function variants

BACKGROUND

Neurodevelopmental disorder with spastic diplegia and visual defects (NEDSDV) is a rare autosomal dominant syndrome, which is caused by the heterozygous germline loss-of-function variants in CTNNB1.

METHODS

We evaluated the clinical and genetic findings of 24 previously undescribed Chinese patients affected by CTNNB1-related disorders and explored the possible ethnicity-related phenotypic variations.

RESULTS

Twenty-one loss-of-function variants were identified within these 24 NEDSDV patients, including 14 novel CTNNB1 variants and 7 recurrent ones. The prominent clinical manifestations in our cohort are developmental delay/intellectual disability (100%), motor delay (100%), speech impairment (100%), dystonia (87.5%) and microcephaly (69.6%). The common facial dysmorphisms were consistent with previous reports, including wide nasal bridge (58.3%), bulbous nose (45.8%), long philtrum (45.8%) and thin upper lip (45.8%). In addition, 19 patients (79.2%) in our cohort had mild visual defects, while one affected individual (4.2%) had familial exudative vitreoretinopathy. Notably, we discovered that 20 patients (83.3%) exhibited various behavioral abnormalities, which is described in Chinese patients for the first time.

CONCLUSION

We provided the largest known Chinese cohort with pathogenic CTNNB1 variants, which not only helps to expand the variant spectrum of CTNNB1 gene, but further delineates the typical phenotype of this disorder in Chinese population.