Global developmental delay, progressive relapsing-remitting parkinsonism, and spinal syrinx in a child with SOX6 mutation

Neurodevelopmental disorder with dystonia due to SOX6 mutations

BACKGROUND

Mutations in SOX6 have recently been recognized as a new molecular cause of neurodevelopmental disorders characterized by intellectual disability, behavioral changes, and nonspecific facial and digital skeletal abnormalities. To date, <25 cases have been reported in the literature.

METHODS AND FINDINGS

Here we report a new case of SOX6-associated neurodegeneration and expand the phenotype to include ceratoconus. The clinical picture consisted of early onset mildly reduced intellectual function, facial asymmetry, and dystonic tremor of hands and neck, substantially improved by levodopa. Skeletal abnormalities included scoliosis and hypertrophy of the mandibular coronoid process. A heterozygous de novo loss-of-function variant in SOX6 (c.277 C>T. p.Arg93*) was molecularly confirmed which leads to truncation of the SOX6 protein in its N-terminus, upstream of any known functional domain.

CONCLUSION

SOX6-associated neurodevelopmental delayis ultrarare with less than 25 cases described in the literature. We report a new case who presented with early-onset mildly reduced intellectual function, facial asymmetry, skeletal abnormalities and dystonic tremor of hands and neck, substantially improved by levodopa. Given the therapeutic implications, SOX6 mutations should be considered in patients with complex dystonia parkinsonism.

The Role of Copy Number Variations and FHIT Gene on Phenotypic Characteristics of Cases Diagnosed with Autism Spectrum Disorder

Copy number variations (CNVs) have been implied in the etiology of autism spectrum disorder (ASD), and microarray-based techniques are performed as a first-step genetic test. Our aim was to present clinical features and CNV profiles of patients with ASD and their parents. Array-CGH was applied to detect CNVs. Previously as likely pathogenic reported duplications were detected at 16p13.11 and 11p15.2p15.1. Other variants were found in 16p11.2p11.1, 3p14.2, 15q11.2, 10q11.22, 3p26.3, 4q13.3, 22q13.32q13.33, and 1q44 and were classified as variants of unknown significance. Deletion of the FHIT gene was associated with the regression of language and social skills without mental impairment. Paternal inheritance of difficulty in social skills and the FHIT gene was documented. In addition, varying olfactory receptor family genes were implicated in de novo and hereditary CNVs. In this study, we aimed to present the clinical characteristics of the cases and parents in more detail, especially in pathogenic CNV cases, which enables us to increase our knowledge on inherited CNVs and genotype-phenotype correlation. We suggest that both genetic and psychiatric evaluation of the parents of the cases is important for better understanding the clinical relevance of the CNV results.

De Novo SOX6 Variants Cause a Neurodevelopmental Syndrome Associated with ADHD, Craniosynostosis, and Osteochondromas

SOX6 belongs to a family of 20 SRY-related HMG-box-containing (SOX) genes that encode transcription factors controlling cell fate and differentiation in many developmental and adult processes. For SOX6, these processes include, but are not limited to, neurogenesis and skeletogenesis. Variants in half of the SOX genes have been shown to cause severe developmental and adult syndromes, referred to as SOXopathies. We here provide evidence that SOX6 variants also cause a SOXopathy. Using clinical and genetic data, we identify 19 individuals harboring various types of SOX6 alterations and exhibiting developmental delay and/or intellectual disability; the individuals are from 17 unrelated families. Additional, inconstant features include attention-deficit/hyperactivity disorder (ADHD), autism, mild facial dysmorphism, craniosynostosis, and multiple osteochondromas. All variants are heterozygous. Fourteen are de novo, one is inherited from a mosaic father, and four offspring from two families have a paternally inherited variant. Intragenic microdeletions, balanced structural rearrangements, frameshifts, and nonsense variants are predicted to inactivate the SOX6 variant allele. Four missense variants occur in residues and protein regions highly conserved evolutionarily. These variants are not detected in the gnomAD control cohort, and the amino acid substitutions are predicted to be damaging. Two of these variants are located in the HMG domain and abolish SOX6 transcriptional activity in vitro. No clear genotype-phenotype correlations are found. Taken together, these findings concur that SOX6 haploinsufficiency leads to a neurodevelopmental SOXopathy that often includes ADHD and abnormal skeletal and other features.

Overlapping genetic architecture between Parkinson disease and melanoma

Epidemiologic studies have reported inconsistent results regarding an association between Parkinson disease (PD) and cutaneous melanoma (melanoma). Identifying shared genetic architecture between these diseases can support epidemiologic findings and identify common risk genes and biological pathways. Here, we apply polygenic, linkage disequilibrium-informed methods to the largest available case-control, genome-wide association study summary statistic data for melanoma and PD. We identify positive and significant genetic correlation (correlation: 0.17, 95% CI 0.10-0.24; P = 4.09 × 10-06) between melanoma and PD. We further demonstrate melanoma and PD-inferred gene expression to overlap across tissues (correlation: 0.14, 95% CI 0.06 to 0.22; P = 7.87 × 10-04) and highlight seven genes including PIEZO1, TRAPPC2L, and SOX6 as potential mediators of the genetic correlation between melanoma and PD. These findings demonstrate specific, shared genetic architecture between PD and melanoma that manifests at the level of gene expression.

SOX6 suppresses the development of lung adenocarcinoma by regulating expression of p53, p21CIPI , cyclin D1 and β-catenin

The Sry‐related high‐mobility group box6 (SOX6) has been implicated in the development of cancer, but its role in lung cancer is incompletely understood. Here, we report that SOX6 expression is frequently down‐regulated in lung adenocarcinoma tissues. Moreover, SOX6 can inhibit the proliferation and invasion of lung adenocarcinoma cells, which may occur through cell cycle arrest at G1/S due to up‐regulation of p53 and p21^CIPI and down‐regulation of cyclin D1 and β‐catenin. Univariate and multivariate analyses revealed that the expression of SOX6 is significantly associated with patient disease‐related survival and is an independent prognostic factor for lung adenocarcinoma. These data suggest that SOX6 may act as a suppressor of lung adenocarcinoma.

Transcription factors in SOX family: Potent regulators for cancer initiation and development in the human body

Transcription factors (TFs) have a key role in controlling the gene regulatory network that sustains explicit cell states in humans. However, an uncontrolled regulation of these genes potentially results in a wide range of diseases, including cancer. Genes of the SOX family are indeed crucial as deregulation of SOX family TFs can potentially lead to changes in cell fate as well as irregular cell growth. SOX TFs are a conserved group of transcriptional regulators that mediate DNA binding through a highly conserved high-mobility group (HMG) domain. Accumulating evidence demonstrates that cell fate and differentiation in major developmental processes are controlled by SOX TFs. Besides; numerous reports indicate that both up- and down-regulation of SOX TFs may induce cancer progression. In this review, we discuss the involvement of key TFs of SOX family in human cancers.

High expression of microRNA-208 is associated with cardiac hypertrophy via the negative regulation of the sex-determining region Y-box 6 protein

The aim of this study was to investigate the expression levels of microRNA-208 (miR-208) and sex-determining region Y-box 6 (SOX6) in patients with progressive cardiac hypertrophy. A total of 50 patients with essential hypertension accompanied by left ventricular hypertrophy, and 30 healthy individuals were enrolled. Peripheral blood samples were collected in order to compare miR-208 expression levels between the cardiac hypertrophy patients and healthy individuals. In addition, an in vitro cellular model of cardiac hypertrophy was established to determine the association between miR-208 and SOX6 expression. Rat cardiomyocytes were treated with phenylephrine (PE) to induce cardiac hypertrophy. Some of the hypertrophic cardiomyocytes were subsequently transfected with antagomiR-208, an miR-208 antagonist, in order to determine the effects of silencing miR-208 expression. Differences between healthy and hypertrophic cardiomyocyte morphology were evaluated using immunofluorescence staining. The mRNA expression levels of the hypertrophy-associated genes β-myosin heavy chain, α-sarcomeric actin and atrial natriuretic peptide were determined using quantitative polymerase chain reaction (qPCR). The mRNA and protein expression levels of miR-208 and SOX6 in peripheral blood and cardiomyocytes were detected using qPCR and western blot analysis, respectively. The expression levels of miR-208 were significantly increased in the peripheral blood of patients with left ventricular hypertrophy (P<0.05). PE-stimulated cardiomyocytes were significantly increased in size compared with normal cardiomyocytes. In the PE-stimulated cardiomyocytes, miR-208 expression levels were significantly increased (P<0.05). However, SOX6 expression levels were significantly decreased compared with those in normal cardiomyocytes (P<0.05). Following transfection with antagomiR-208, SOX6 expression levels in the PE-stimulated cardiomyocytes significantly increased, while the total mRNA and protein expression levels of hypertrophy-associated genes significantly decreased (P<0.05). miR-208 expression levels are increased in the peripheral blood of patients with cardiac hypertrophy. Therefore, the results of this study suggest that the expression levels of miR-208 are associated with cardiac hypertrophy by the negative regulation of SOX6.

Disruption of SOX6 is associated with a rapid-onset dopa-responsive movement disorder, delayed development, and dysmorphic features

BACKGROUND

Sox6 is a transcription factor that is crucial for the differentiation and development of cortical interneurons and dopaminergic neurons of the substantia nigra pars compact. Loss-of-function mutations might thus result in complex paroxysmal diseases such as epilepsy syndromes or movement disorders.

PATIENT

We present a 15-year-old boy with delayed speech development and attention deficit hyperactivity disorder who presented with a rapid-onset generalized dopa-responsive dystonia.

RESULTS

Neurological examination revealed generalized dystonic and frequent athetoid movements of the arms, trunk, and neck. Gait was severely impaired secondary to frequent dystonic postures. Both a resting tremor and action tremors were observed in both hands. Speech was dysarthric but language comprehension was unimpaired. Testing for saccadic dysfunction revealed hypometric horizontal and vertical saccades. Physical examination was otherwise significant for a pectus carinatum and splenomegaly. Laboratory studies, brain magnetic resonance imaging, and electroencephalography were unremarkable. Treatment with levodopa/carbidopa led to a complete and sustained remission of neurological symptoms. Genetic testing revealed a mono-allelic de novo 84-kb deletion on chromosome 11p15.2 encompassing exons 14-16 of the SOX6 gene (chr11: 15944880-16029095, NCBI 37/hg19).

CONCLUSIONS

This is the first report of a dopa-responsive movement disorder associated with SOX6 disruption. SOX6 mutations should be considered in the differential diagnosis of unexplained dopa-responsive dystonia syndromes.

Sox6 and Otx2 control the specification of substantia nigra and ventral tegmental area dopamine neurons

Distinct midbrain dopamine (mDA) neuron subtypes are found in the substantia nigra pars compacta (SNc) and the ventral tegmental area (VTA), but it is mainly SNc neurons that degenerate in Parkinson's disease. Interest in how mDA neurons develop has been stimulated by the potential use of stem cells in therapy or disease modeling. However, very little is known about how specific dopaminergic subtypes are generated. Here, we show that the expression profiles of the transcription factors Sox6, Otx2, and Nolz1 define subpopulations of mDA neurons already at the neural progenitor cell stage. After cell-cycle exit, Sox6 selectively localizes to SNc neurons, while Otx2 and Nolz1 are expressed in a subset of VTA neurons. Importantly, Sox6 ablation leads to decreased expression of SNc markers and a corresponding increase in VTA markers, while Otx2 ablation has the opposite effect. Moreover, deletion of Sox6 affects striatal innervation and dopamine levels. We also find reduced Sox6 levels in Parkinson's disease patients. These findings identify Sox6 as a determinant of SNc neuron development and should facilitate the engineering of relevant mDA neurons for cell therapy and disease modeling.