De novo microdeletions and point mutations affecting SOX2 in three individuals with intellectual disability but without major eye malformations

Treatment of Asymmetric Crying Face by Fascia lata Grafting

OBJECTIVE

To evaluate and discuss the plastic surgery treatment of asymmetric crying face.

METHODS

From 2019 to 2022, 60 patients with asymmetric crying face were treated by fascia lata grafting. We evaluated the postoperative improvement, summarized experiences and reviewed literatures about the treatment of asymmetric crying face.

RESULTS

59 patients showed varying degrees of improvement in the movement of the affected corner of mouth, and no complications were found during the follow-up period of 6 months to 24 months.

CONCLUSIONS

The cause of asymmetric crying face is still uncertain. Fascia lata grafting has shown a certain effect in the treatment of asymmetric crying face. This study evaluated this method with quite large sample. More researches are needed to explore the most appropriate treatment for asymmetric crying face.

Deciphering neuronal deficit and protein profile changes in human brain organoids from patients with creatine transporter deficiency

Creatine transporter deficiency (CTD) is an X-linked disease caused by mutations in the SLC6A8 gene. The impaired creatine uptake in the brain results in intellectual disability, behavioral disorders, language delay, and seizures. In this work, we generated human brain organoids from induced pluripotent stem cells of healthy subjects and CTD patients. Brain organoids from CTD donors had reduced creatine uptake compared with those from healthy donors. The expression of neural progenitor cell markers SOX2 and PAX6 was reduced in CTD-derived organoids, while GSK3β, a key regulator of neurogenesis, was up-regulated. Shotgun proteomics combined with integrative bioinformatic and statistical analysis identified changes in the abundance of proteins associated with intellectual disability, epilepsy, and autism. Re-establishment of the expression of a functional SLC6A8 in CTD-derived organoids restored creatine uptake and normalized the expression of SOX2, GSK3β, and other key proteins associated with clinical features of CTD patients. Our brain organoid model opens new avenues for further characterizing the CTD pathophysiology and supports the concept that reinstating creatine levels in patients with CTD could result in therapeutic efficacy.

SOX2 pathogenic variants with normal eyes: Expanding the phenotypic spectrum

SOX2 pathogenic variants, though rare, constitute the most commonly known genetic cause of clinical anophthalmia and microphthalmia. However, patients without major ocular malformation, but with multi-system developmental disorders, have been reported, suggesting that the range of clinical phenotypes is broader than previously appreciated. We detail two patients with bilateral structurally normal eyes along with 11 other previously published patients. Our findings suggest that there is no obvious phenotypic or genotypic pattern that may help set apart patients with normal eyes. Our patients provide further evidence for broadening the phenotypic spectrum of SOX2 mutations and re-appraising the designation of SOX2 disorder as an anophthalmia/microphthalmia syndrome. We emphasize the importance of considering SOX2 pathogenic variants in the differential diagnoses of individuals with normal eyes, who may have varying combinations of features such as developmental delay, urogenital abnormalities, gastro-intestinal anomalies, pituitary dysfunction, midline structural anomalies, and complex movement disorders, seizures or other neurological issues.

Review of 37 patients with SOX2 pathogenic variants collected by the Anophthalmia/Microphthalmia Clinical Registry and DNA research study

SOX2 variants and deletions are a common cause of anophthalmia and microphthalmia (A/M). This article presents data from a cohort of patients with SOX2 variants, some of whom have been followed for 20+ years. Medical records from patients enrolled in the A/M Research Registry and carrying SOX2 variants were reviewed. Thirty-seven patients were identified, ranging in age from infant to 30 years old. Eye anomalies were bilateral in 30 patients (81.1%), unilateral in 5 (13.5%), and absent in 2 (5.4%). Intellectual disability was present in all with data available and ranged from mild to profound. Seizures were noted in 18 of 27 (66.6%) patients, usually with abnormal brain MRIs (10/15, 66.7%). Growth issues were reported in 14 of 21 patients (66.7%) and 14 of 19 (73.7%) had gonadotropin deficiency. Genitourinary anomalies were seen in 15 of 19 (78.9%) male patients and 5 of 15 (33.3%) female patients. Patients with SOX2 nucleotide variants, whole gene deletions or translocations are typically affected with bilateral or unilateral microphthalmia and anophthalmia. Other associated features include intellectual disability, seizures, brain anomalies, growth hormone deficiency, gonadotropin deficiency, and genitourinary anomalies. Recommendations for newly diagnosed patients with SOX2 variants include eye exams, MRI of the brain and orbits, endocrine and neurology examinations. Since the clinical spectrum associated with SOX2 alleles has expanded beyond the originally reported phenotypes, we propose a broader term, SOX2-associated disorder, for this condition.

Gait disturbance in a patient with de novo 1.0-kb SOX2 microdeletion

BACKGROUND

Sex-determining region Y-box 2 (SOX2) plays an important role in the early embryogenesis of the eye, forebrain, and hypothalamic-pituitary axis. Anophthalmia, microphthalmia, and hormonal abnormalities are commonly observed in patients with SOX2-related disorders. Although gait disturbance, particularly ataxic gait, has recently been observed in several cases, detailed data regarding the clinical course of gait disturbance in SOX2-related disorders are limited.

CASE REPORT

A 9-year-old Japanese boy presented with focal dyskinesia only during walking and running after he started walking at the age of 3 years. He also exhibited intellectual disability and mild dysmorphic features, including microcephaly, micropenis, and short stature associated with hormonal abnormalities. Gait disturbance with involuntary extremity movements only during walking and running was indicative of choreoathetosis and dystonia. Genetic analysis detected a de novo heterozygous 1.0-kb deletion including SOX2 at 3q26.32, as described in a previous technical paper.

CONCLUSIONS

SOX2-related disorders should be considered in patients with some anomalies having a differential diagnosis of dyskinesia. Focal dyskinesia only during walking and running may be a characteristic feature of SOX2-related disorders.

Clinical diagnosis of presumed SOX2 gonadosomatic mosaicism

Purpose:

To describe a family with presumed SOX2 gonadosomatic mosaicism diagnosed upon ophthalmic examination of the proband’s mother.

Methods:

The family underwent comprehensive ophthalmic and physical examination. Variant detection was performed using trio exome analysis on peripheral leukocyte DNA from blood and saliva samples. Variant segregation analysis was performed using a custom panel NGS sequencing. An identified variant in the SOX2 gene was confirmed in the proband by Sanger sequencing.

Results:

We report an individual with bilateral microphthalmia, developmental delay, hearing loss, and dysmorphic features. Her mother was found to have asymptomatic forme fruste uveal coloboma affecting her anterior segment. Her father, aunt, and sisters were unaffected. Trio exome sequence analysis showed an apparent de novo heterozygous deletion in the proband, NM_003106.3:c.70_89del, NP_003097.1:p. (Asn24Argfs*65), classified as pathogenic. Testing of the other family members’ peripheral blood and saliva was negative for this variant. The iris transillumination abnormalities in the proband’s mother supports a gonadosomatic mosaicism scenario.

Conclusions:

The results from this family underscore the importance of performing detailed evaluations of the parents of apparently sporadically affected individuals with heritable ophthalmic disorders. The identification of mildly affected individuals could substantially alter recurrence risks.

Dynamic expression of NR2F1 and SOX2 in developing and adult human cortex: comparison with cortical malformations

The neocortex, the most recently evolved brain region in mammals, is characterized by its unique areal and laminar organization. Distinct cortical layers and areas can be identified by the presence of graded expression of transcription factors and molecular determinants defining neuronal identity. However, little is known about the expression of key master genes orchestrating human cortical development. In this study, we explored the expression dynamics of NR2F1 and SOX2, key cortical genes whose mutations in human patients cause severe neurodevelopmental syndromes. We focused on physiological conditions, spanning from mid-late gestational ages to adulthood in unaffected specimens, but also investigated gene expression in a pathological context, a developmental cortical malformation termed focal cortical dysplasia (FCD). We found that NR2F1 follows an antero-dorsal^low to postero-ventral^high gradient as in the murine cortex, suggesting high evolutionary conservation. While SOX2 is mainly expressed in neural progenitors next to the ventricular surface, NR2F1 is found in both mitotic progenitors and post-mitotic neurons at GW18. Interestingly, both proteins are highly co-expressed in basal radial glia progenitors of the outer sub-ventricular zone (OSVZ), a proliferative region known to contribute to cortical expansion and complexity in humans. Later on, SOX2 becomes largely restricted to astrocytes and oligodendrocytes although it is also detected in scattered mature interneurons. Differently, NR2F1 maintains its distinct neuronal expression during the whole process of cortical development. Notably, we report here high levels of NR2F1 in dysmorphic neurons and NR2F1 and SOX2 in balloon cells of surgical samples from patients with FCD, suggesting their potential use in the histopathological characterization of this dysplasia.

Recent developments in genetic/genomic medicine

Advances in genetic technology are having a major impact in the clinic, and mean that many perceptions of the role and scope of genetic testing are having to change. Genomic testing brings with it a greater opportunity for diagnosis, or predictions of future diagnoses, but also an increased chance of uncertain or unexpected findings, many of which may have impacts for multiple members of a person's family. In the past, genetic testing was rarely able to provide rapid results, but the increasing speed and availability of genomic testing is changing this, meaning that genomic information is increasingly influencing decisions around patient care in the acute inpatient setting. The landscape of treatment options for genetic conditions is shifting, which has evolving implications for clinical discussions around previously untreatable disorders. Furthermore, the point of access to testing is changing with increasing provision direct to the consumer outside the formal healthcare setting. This review outlines the ways in which genetic medicine is developing in light of technological advances.

Genetics of anophthalmia and microphthalmia. Part 1: Non-syndromic anophthalmia/microphthalmia

Eye formation is the result of coordinated induction and differentiation processes during embryogenesis. Disruption of any one of these events has the potential to cause ocular growth and structural defects, such as anophthalmia and microphthalmia (A/M). A/M can be isolated or occur with systemic anomalies, when they may form part of a recognizable syndrome. Their etiology includes genetic and environmental factors; several hundred genes involved in ocular development have been identified in humans or animal models. In humans, around 30 genes have been repeatedly implicated in A/M families, although many other genes have been described in single cases or families, and some genetic syndromes include eye anomalies occasionally as part of a wider phenotype. As a result of this broad genetic heterogeneity, with one or two notable exceptions, each gene explains only a small percentage of cases. Given the overlapping phenotypes, these genes can be most efficiently tested on panels or by whole exome/genome sequencing for the purposes of molecular diagnosis. However, despite whole exome/genome testing more than half of patients currently remain without a molecular diagnosis. The proportion of undiagnosed cases is even higher in those individuals with unilateral or milder phenotypes. Furthermore, even when a strong gene candidate is available for a patient, issues of incomplete penetrance and germinal mosaicism make diagnosis and genetic counseling challenging. In this review, we present the main genes implicated in non-syndromic human A/M phenotypes and, for practical purposes, classify them according to the most frequent or predominant phenotype each is associated with. Our intention is that this will allow clinicians to rank and prioritize their molecular analyses and interpretations according to the phenotypes of their patients.

Extension of the mutational and clinical spectrum of SOX2 related disorders: Description of six new cases and a novel association with suprasellar teratoma

SOX2 is a transcription factor that is essential for maintenance of pluripotency and has several conserved roles in early embryonic development. Heterozygous loss-of-function variants in SOX2 are identified in approximately 40% of all cases of bilateral anophthalmia/micropthalmia (A/M). Increasingly SOX2 mutation-positive patients without major eye findings, but with a range of other developmental disorders including autism, mild to moderate intellectual disability with or without structural brain changes, esophageal atresia, urogenital anomalies, and endocrinopathy are being reported, suggesting that the clinical phenotype associated with SOX2 loss is much broader than previously appreciated. In this report we describe six new cases, four of which carry novel pathogenic SOX2 variants. Four cases presented with bilateral anophthalmia in addition to extraocular involvement. Another individual presented with only unilateral anophthalmia. One individual did not have any eye findings but presented with a suprasellar teratoma in infancy and was found to have the recurrent c.70del20 mutation in SOX2 (c.70_89del, p.Asn24Argfs*65). This is this first time this tumor type has been reported in the context of a de novo SOX2 mutation. Notably, individuals with hypothalamic hamartomas and slow-growing hypothalamo-pituitary tumors have been reported previously, but it is still unclear how SOX2 loss contributes to their formation.

Genetics of anophthalmia and microphthalmia. Part 2: Syndromes associated with anophthalmia-microphthalmia

As new genes for A/M are identified in the genomic era, the number of syndromes associated with A/M has greatly expanded. In this review, we provide a brief synopsis of the clinical presentation and molecular genetic etiology of previously characterized pathways involved in A/M, including the Sex-determining region Y-box 2 (SOX2), Orthodenticle Homeobox 2 (OTX2) and Paired box protein-6 (PAX6) genes, and the Stimulated by retinoic acid gene 6 homolog (STRA6), Aldehyde Dehydrogenase 1 Family Member A3 (ALDH1A3), and RA Receptor Beta (RARβ) genes that are involved in retinoic acid synthesis. Less common genetic causes of A/M, including genes involved in BMP signaling [Bone Morphogenetic Protein 4 (BMP4), Bone Morphogenetic Protein 7 (BMP7) and SPARC-related modular calcium-binding protein 1 (SMOC1)], genes involved in the mitochondrial respiratory chain complex [Holocytochrome c-type synthase (HCCS), Cytochrome C Oxidase Subunit 7B (COX7B), and NADH:Ubiquinone Oxidoreductase subunit B11 (NDUFB11)], the BCL-6 corepressor gene (BCOR), Yes-Associated Protein 1 (YAP1) and Transcription Factor AP-2 Alpha (TFAP2α), are more briefly discussed. We also review several recently described genes and pathways associated with A/M, including Smoothened (SMO) that is involved in Sonic hedgehog (SHH) signaling, Structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1) and Solute carrier family 25 member 24 (SLC25A24), emphasizing phenotype-genotype correlations and shared pathways where relevant.

Sox2 conditional mutation in mouse causes ataxic symptoms, cerebellar vermis hypoplasia, and postnatal defects of Bergmann glia

Sox2 is a transcription factor active in the nervous system, within different cell types, ranging from radial glia neural stem cells to a few specific types of differentiated glia and neurons. Mutations in the human SOX2 transcription factor gene cause various central nervous system (CNS) abnormalities, involving hippocampus and eye defects, as well as ataxia. Conditional Sox2 mutation in mouse, with different Cre transgenes, previously recapitulated different essential features of the disease, such as hippocampus and eye defects. In the cerebellum, Sox2 is active from early embryogenesis in the neural progenitors of the cerebellar primordium; Sox2 expression is maintained, postnatally, within Bergmann glia (BG), a differentiated cell type essential for Purkinje neurons functionality and correct motor control. By performing Sox2 Cre-mediated ablation in the developing and postnatal mouse cerebellum, we reproduced ataxia features. Embryonic Sox2 deletion (with Wnt1Cre) leads to reduction of the cerebellar vermis, known to be commonly related to ataxia, preceded by deregulation of Otx2 and Gbx2, critical regulators of vermis development. Postnatally, BG is progressively disorganized, mislocalized, and reduced in mutants. Sox2 postnatal deletion, specifically induced in glia (with GLAST-CreERT2), reproduces the BG defect, and causes (milder) ataxic features. Our results define a role for Sox2 in cerebellar function and development, and identify a functional requirement for Sox2 within postnatal BG, of potential relevance for ataxia in mouse mutants, and in human patients.

SOX2: Not always eye malformations. Severe genital but no major ocular anomalies in a female patient with the recurrent c.70del20 variant

SOX2 variants have been identified in multiple patients with severe ocular anomalies and pituitary dysfunction, in addition to various systemic features. We investigated a 26-year-old female patient suffering from spastic paraparesis, hypoplasia of corpus callosum, hypogonadotropic hypogonadism (HH) and intellectual disability, who was monitored for over 20 years, allowing a detailed genotype-phenotype correlation along time. Whole exome sequencing on the patient and her relatives identified a de novo SOX2 c.70del20 variant, which has been frequently reported in individuals with SOX2-related anophthalmia. Importantly, our patient lacked major ocular phenotype but showed vaginal agenesis, a feature never reported before. Although the involvement of male urogenital tract (cryptorchidism, hypospadias, small penis), is a well known consequence of SOX2 variants, their effect on the female genitalia has never been properly addressed, even considering the paradoxical female excess of SOX2 cases in the literature. Our findings emphasize the importance of testing for SOX2 variants in individuals with HH and genital anomalies even though anophthalmia or microphthalmia are not observed. Moreover, our case strengthens the role of SOX2 as a master regulator of female gonadal differentiation, as widely demonstrated for other SOX genes related to 46, XX sex reversal, such as SOX3 and SOX9.