Aortic disease and cardiomyopathy in patients with a novel DNMT3A gene variant causing Tatton-Brown-Rahman syndrome.

Tatton-Brown-Rahman syndrome (TBRS) is a rare congenital genetic disorder caused by autosomal dominant pathogenic variants in the DNA methyltransferase DNMT3A gene. Typical TBRS clinical features are overgrowth, intellectual disability, and minor facial anomalies. However, since the syndrome was first described in 2014, a widening spectrum of abnormalities is being described. Cardiovascular abnormalities are less commonly reported but can be a major complication of the syndrome. This article describes a family of three individuals diagnosed with TBRS in adulthood and highlights the variable expression of cardiovascular features. A 34-year-old proband presented with progressive aortic dilatation, mitral valve (MV) regurgitation, left ventricular (LV) dilatation, and ventricular arrhythmias. The affected family members (mother and brother) were diagnosed with MV regurgitation, LV dilatation, and arrhythmias. Exome sequencing and computational protein analysis suggested that the novel familial DNMT3A mutation Ser775Tyr is located in the methyltransferase domain, however, distant from the active site or DNA-binding loops. Nevertheless, this bulky substitution may have a significant effect on DNMT3A protein structure, dynamics, and function. Analysis of peripheral blood cfDNA and transcriptome showed shortened mononucleosome fragments and altered gene expression in a number of genes related to cardiovascular health and of yet undescribed function, including several lncRNAs. This highlights the importance of epigenetic regulation by DNMT3A on cardiovascular system development and function. From the clinical perspective, we suggest that new patients diagnosed with congenital DNMT3A variants and TBRS require close examination and follow-up for aortic dilatation and valvular disease because these conditions can progress rapidly. Moreover, personalized treatments, based on the specific DNMT3A variants and the different pathways of their function loss, can be envisioned in the future.

Novel SETBP1 D874V adjacent to the degron causes canonical schinzel-giedion syndrome: a case report and review of the literature.

Schinzel-Giedion syndrome (SGS) is a severe multisystem disorder characterized by distinctive facial features, profound intellectual disability, refractory epilepsy, cortical visual impairment, hearing loss, and various congenital anomalies. SGS is attributed to gain-of-function (GoF) variants in the SETBP1 gene, with reported variants causing canonical SGS located within a 12 bp hotspot region encoding SETBP1 residues aa868-871 (degron). Here, we describe a case of typical SGS caused by a novel heterozygous missense variant, D874V, adjacent to the degron. The female patient was diagnosed in the neonatal period and presented with characteristic facial phenotype (midface retraction, prominent forehead, and low-set ears), bilateral symmetrical talipes equinovarus, overlapping toes, and severe bilateral hydronephrosis accompanied by congenital heart disease, consistent with canonical SGS. This is the first report of a typical SGS caused by a, SETBP1 non-degron missense variant. This case expands the genetic spectrum of SGS and provides new insights into genotype-phenotype correlations.

Diagnosis of Arboleda-Tham syndrome by whole-exome sequencing in an Asian girl with severe developmental delay.

OBJECTIVE: This study aims to report a severe phenotype of Arboleda-Tham syndrome in a 20-month-old girl, characterized by global developmental delay, distinct facial features, intellectual disability. Arboleda-Tham syndrome is known for its wide phenotypic spectrum and is associated with truncating variants in the KAT6A gene. METHODS: To diagnose this case, a combination of clinical phenotype assessment and whole-exome sequencing technology was employed. The genetic analysis involved whole-exome sequencing, followed by confirmation of the identified variant through Sanger sequencing. RESULTS: The whole-exome sequencing revealed a novel de novo frameshift mutation c.3048del (p.Leu1017Serfs*17) in the KAT6A gene, which is classified as likely pathogenic. This mutation was not found in the ClinVar and HGMD databases and was not present in her parents. The mutation leads to protein truncation or activation of nonsense-mediated mRNA degradation. The mutation is located within exon 16, potentially leading to protein truncation or activation of nonsense-mediated mRNA degradation. Protein modeling suggested that the de novo KAT6A mutation might alter hydrogen bonding and reduce protein stability, potentially damaging the protein structure and function. CONCLUSION: This study expands the understanding of the genetic basis of Arboleda-Tham syndrome, highlighting the importance of whole-exome sequencing in diagnosing cases with varied clinical presentations. The discovery of the novel KAT6A mutation adds to the spectrum of known pathogenic variants and underscores the significance of this gene in the syndrome's pathology.

Expanding the phenotype in Pitt-Hopkins syndrome; description of new oral finding and dental management considerations.

BACKGROUND: Pitt-Hopkins syndrome (PTHS) is a rare neurodevelopmental disorder with physical, cognitive, and behavioral characteristics that is caused by heterozygous mutations in the TCF4 gene. Patients with PTHS might present a unique challenge for oral healthcare professionals because of the associated comorbidities. CASE REPORT: Here we describe a new case of PTHS in a 13-year-old girl with particular emphasis on oro-dental findings and oral healthcare management. Observed oro-dental findings in our case included shallow palate, absence of lingual frenum, gingival enlargement, thick lips and relative microdontia. The patient was unable to tolerate dental care under local anesthesia. Therefore, comprehensive dental treatment was performed under general anesthesia after a careful pre-anesthetic cardio-respiratory, neurological, and hematological evaluation. The patient was closely monitored intra-operatively for breathing rhythm, O2 saturation, and signs of respiratory distress. The patient was observed for 24 h post-op for respiratory distress and was discharged then uneventfully. CONCLUSION: Dental treatment under general anesthesia in these patients might be complicated by the abnormal breathing rhythm, and close monitoring and follow up for signs of respiratory distress after general anesthesia is necessary. Recognition of oral and dental findings might help to expand the phenotype and better characterize rare syndromes.

Genetic heterogeneity in epilepsy and comorbidities: insights from Pakistani families.

BACKGROUND: Epilepsy, a challenging neurological condition, is often present with comorbidities that significantly impact diagnosis and management. In the Pakistani population, where financial limitations and geographical challenges hinder access to advanced diagnostic methods, understanding the genetic underpinnings of epilepsy and its associated conditions becomes crucial. METHODS: This study investigated four distinct Pakistani families, each presenting with epilepsy and a spectrum of comorbidities, using a combination of whole exome sequencing (WES) and Sanger sequencing. The epileptic patients were prescribed multiple antiseizure medications (ASMs), yet their seizures persist, indicating the challenging nature of ASM-resistant epilepsy. RESULTS: Identified genetic variants contributed to a diverse range of clinical phenotypes. In the family 1, which presented with epilepsy, developmental delay (DD), sleep disturbance, and aggressive behavior, a homozygous splice site variant, c.1339-6 C > T, in the COL18A1 gene was detected. The family 2 exhibited epilepsy, intellectual disability (ID), DD, and anxiety phenotypes, a homozygous missense variant, c.344T > A (p. Val115Glu), in the UFSP2 gene was identified. In family 3, which displayed epilepsy, ataxia, ID, DD, and speech impediment, a novel homozygous frameshift variant, c.1926_1941del (p. Tyr643MetfsX2), in the ZFYVE26 gene was found. Lastly, family 4 was presented with epilepsy, ID, DD, deafness, drooling, speech impediment, hypotonia, and a weak cry. A homozygous missense variant, c.1208 C > A (p. Ala403Glu), in the ATP13A2 gene was identified. CONCLUSION: This study highlights the genetic heterogeneity in ASM-resistant epilepsy and comorbidities among Pakistani families, emphasizing the importance of genotype-phenotype correlation and the necessity for expanded genetic testing in complex clinical cases.

[Clinical and genetic analysis of a child with X-linked mental retardation due to variant of SLC9A7 gene].

OBJECTIVE: To explore the clinical and genetic characteristics of a child with mental retardation, language and motor developmental delay and epilepsy. METHODS: A child who was admitted to the First Affiliated Hospital of Zhengzhou University in March 2020 for intermittent seizures for over two months was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples of the child and his parents were collected and subjected to high throughput sequencing. Candidate variants were verified by Sanger sequencing and bioinformatic analysis. RESULTS: The clinical manifestations of the child have included mental retardation, language and motor developmental delay, and seizures. High-throughput sequencing revealed that he has harbored a hemizygous splice site variant (NM_032591.3: c.1030-1G>C) of the SLC9A7 gene, which was inherited from his mother and unreported previously. CONCLUSION: The hemizygous splice site variant (NM_032591.3: c.1030-1G>C) of the SLC9A7 gene probably underlay the disease in this child. Above finding has provided a basis for clinical diagnosis and genetic counseling.

A Missense Variant in HACE1 Is Associated with Intellectual Disability, Epilepsy, Spasticity, and Psychomotor Impairment in a Pakistani Kindred.

Intellectual disability (ID), which affects around 2% to 3% of the population, accounts for 0.63% of the overall prevalence of neurodevelopmental disorders (NDD). ID is characterized by limitations in a person's intellectual and adaptive functioning, and is caused by pathogenic variants in more than 1000 genes. Here, we report a rare missense variant (c.350T>C; p.(Leu117Ser)) in HACE1 segregating with NDD syndrome with clinical features including ID, epilepsy, spasticity, global developmental delay, and psychomotor impairment in two siblings of a consanguineous Pakistani kindred. HACE1 encodes a HECT domain and ankyrin repeat containing E3 ubiquitin protein ligase 1 (HACE1), which is involved in protein ubiquitination, localization, and cell division. HACE1 is also predicted to interact with several proteins that have been previously implicated in the ID phenotype in humans. The p.(Leu117Ser) variant replaces an evolutionarily conserved residue of HACE1 and is predicted to be deleterious by various in silico algorithms. Previously, eleven protein truncating variants of HACE1 have been reported in individuals with NDD. However, to our knowledge, p.(Leu117Ser) is the second missense variant in HACE1 found in an individual with NDD.

NR4A2 as a Novel Target Gene for Developmental and Epileptic Encephalopathy: A Systematic Review of Related Disorders and Therapeutic Strategies.

The NR4A2 gene encodes an orphan transcription factor of the steroid-thyroid hormone-retinoid receptor superfamily. This review focuses on the clinical findings associated with the pathogenic variants so far reported, including three unreported cases. Also, its role in neurodegenerative diseases, such as Parkinson's or Alzheimer's disease, is examined, as well as a brief exploration on recent proposals to develop novel therapies for these neurological diseases based on small molecules that could modulate NR4A2 transcriptional activity. The main characteristic shared by all patients is mild to severe developmental delay/intellectual disability. Moderate to severe disorder of the expressive and receptive language is present in at least 42%, while neuro-psychiatric issues were reported in 53% of patients. Movement disorders, including dystonia, chorea or ataxia, are described in 37% patients, although probably underestimated because of its frequent onset in late adolescence-young adulthood. Finally, epilepsy was surprisingly present in 42% of patients, being drug-resistant in three of them. The age at onset varied widely, from five months to twenty-six years, as did the classification of epilepsy, which ranged from focal epilepsy to infantile spasms or Lennox-Gastaut syndrome. Accordingly, we propose that NR4A2 should be considered as a first-tier target gene for the genetic diagnosis of developmental and epileptic encephalopathy.

Neuropsychological profile associated with KAT6A syndrome: Emergent genotype-phenotype trends.

BACKGROUND: KAT6A (Arboleda-Tham) syndrome is a Mendelian disorder of the epigenetic machinery caused by pathogenic variants in the lysine acetyltransferase 6 A (KAT6A) gene. Intellectual disability and speech/language impairment (e.g., minimally verbal) are common features of the disorder, with late-truncating variants associated with a more severe form of intellectual disability. However, much of the cognitive phenotype remains elusive given the dearth of research. PARTICIPANTS AND METHODS: This study examined non-verbal and social skills of 15 individuals with molecularly-confirmed diagnoses of KAT6A syndrome (Mean age = 10.32 years, SD = 4.12). Participants completed select subtests from the DAS-II, the NEPSY-II, and the Beery Buktenica Developmental Test of Visual Motor Integration 6th Edition, and their caregivers completed an assortment of behavior rating inventories. RESULTS: Findings suggest global cognitive impairment with nonverbal cognition scores similar to those for receptive language. Autism-related features, particularly restricted interests and repetitive behaviors, and broad adaptive deficits were common in our sample juxtaposed with a relatively strong social drive and low frequency of internalizing and externalizing behavioral problems. A general trend of lower performance scores on nonverbal and receptive language measures was observed among those with protein-truncating variants vs. missense variants; however, no effect was observed on caregiver rating inventories of daily behaviors. Late and early truncating variants yielded comparable neuropsychological profiles. CONCLUSIONS: Overall, study results show the cognitive phenotype of KAT6A syndrome includes equally impaired nonverbal cognition and receptive language functioning, paired with relatively intact social drive and strengths in behavior regulation. Emergent genotype-phenotype correlations suggest cognition may be more affected in protein-truncating than missense mutations although similar neurobehavioral profiles were observed.

Biallelic variants in CSMD1 are implicated in a neurodevelopmental disorder with intellectual disability and variable cortical malformations.

CSMD1 (Cub and Sushi Multiple Domains 1) is a well-recognized regulator of the complement cascade, an important component of the innate immune response. CSMD1 is highly expressed in the central nervous system (CNS) where emergent functions of the complement pathway modulate neural development and synaptic activity. While a genetic risk factor for neuropsychiatric disorders, the role of CSMD1 in neurodevelopmental disorders is unclear. Through international variant sharing, we identified inherited biallelic CSMD1 variants in eight individuals from six families of diverse ancestry who present with global developmental delay, intellectual disability, microcephaly, and polymicrogyria. We modeled CSMD1 loss-of-function (LOF) pathogenesis in early-stage forebrain organoids differentiated from CSMD1 knockout human embryonic stem cells (hESCs). We show that CSMD1 is necessary for neuroepithelial cytoarchitecture and synchronous differentiation. In summary, we identified a critical role for CSMD1 in brain development and biallelic CSMD1 variants as the molecular basis of a previously undefined neurodevelopmental disorder.

Generation of induced pluripotent stem cell lines from two unrelated patients affected by intellectual disability carrying homozygous variants in SGIP1.

Intellectual disability (ID) is a diverse neurodevelopmental condition and almost half of the cases have a genetic etiology. SGIP1 acts as an endocytic protein that influences the signaling of receptors in neuronal systems related to energy homeostasis through its interaction with endophilins. This study focuses on the generation and characterization of induced pluripotent stem cells (iPSC) from two unrelated patients due to a frameshift variant (c.764dupA, NM_032291.4) and a splice donor site variant (c.74 + 1G > A, NM_032291.4) in the SGIP1 gene.

Neuroectoderm phenotypes in a human stem cell model of O-GlcNAc transferase associated with intellectual disability.

Pathogenic variants in the O-GlcNAc transferase gene (OGT) have been associated with a congenital disorder of glycosylation (OGT-CDG), presenting with intellectual disability which may be of neuroectodermal origin. To test the hypothesis that pathology is linked to defects in differentiation during early embryogenesis, we developed an OGT-CDG induced pluripotent stem cell line together with isogenic control generated by CRISPR/Cas9 gene-editing. Although the OGT-CDG variant leads to a significant decrease in OGT and O-GlcNAcase protein levels, there were no changes in differentiation potential or stemness. However, differentiation into ectoderm resulted in significant differences in O-GlcNAc homeostasis. Further differentiation to neuronal stem cells revealed differences in morphology between patient and control lines, accompanied by disruption of the O-GlcNAc pathway. This suggests a critical role for O-GlcNAcylation in early neuroectoderm architecture, with robust compensatory mechanisms in the earliest stages of stem cell differentiation.

ALG13-Congenital Disorder of Glycosylation (ALG13-CDG): Updated clinical and molecular review and clinical management guidelines.

ALG13-Congenital Disorder of Glycosylation (CDG), is a rare X-linked CDG caused by pathogenic variants in ALG13 (OMIM 300776) that affects the N-linked glycosylation pathway. Affected individuals present with a predominantly neurological manifestation during infancy. Epileptic spasms are a common presenting symptom of ALG13-CDG. Other common phenotypes include developmental delay, seizures, intellectual disability, microcephaly, and hypotonia. Current management of ALG13-CDG is targeted to address patients' symptoms. To date, less than 100 individuals have been reported with ALG13-CDG. In this article, an international group of experts in CDG reviewed all reported individuals affected with ALG13-CDG and suggested diagnostic and management guidelines for ALG13-CDG. The guidelines are based on the best available data and expert opinion. Neurological symptoms dominate the phenotype of ALG13-CDG where epileptic spasm is confirmed to be the most common presenting symptom of ALG13-CDG in association with hypotonia and developmental delay. We propose that ACTH/prednisolone treatment should be trialed first, followed by vigabatrin, however ketogenic diet has been shown to have promising results in ALG13-CDG. In order to optimize medical management, we also suggest early cardiac, gastrointestinal, skeletal, and behavioral assessments in affected patients.

De novo variation in ARID1B gene causes Coffin-Siris syndrome 1 in a Chinese family with excessive early-onset high myopia.

Coffin-Siris syndrome (CSS) is a rare autosomal dominant inheritance disorder characterized by distinctive facial features, hypoplasia of the distal phalanx or nail of the fifth and additional digits, developmental or cognitive delay of varying degree, hypotonia, hirsutism/hypertrichosis, sparse scalp hair and varying kind of congenital anomalies. CSS can easily be misdiagnosed as other syndromes or disorders with a similar clinical picture because of their genetic and phenotypic heterogeneity. We describde the genotype-phenotype correlation of one patient from a healthy Chinese family with a novel genotype underlying CSS, who was first diagnosed in the ophthalmology department as early-onset high myopia (eoHM). Comprehensive ophthalmic tests as well as other systemic examinations were performed on participants to confirm the phenotype. The genotype was identified using whole exome sequencing, and further verified the results among other family members by Sanger sequencing. Real-time quantitative PCR (RT-qPCR) technology was used to detect the relative mRNA expression levels of candidate genes between proband and normal family members. The pathogenicity of the identified variant was determined by The American College of Medical Genetics and Genomics (ACMG) guidelines. STRING protein-protein interactions (PPIs) network analysis was used to detect the interaction of candidate gene-related proteins with high myopia gene-related proteins. The patient had excessive eoHM, cone-rod dystrophy, coarse face, excessive hair growth on the face, sparse scalp hair, developmental delay, intellectual disability, moderate hearing loss, dental hypoplasia, patent foramen ovale, chronic non-atrophic gastritis, bilateral renal cysts, cisterna magna, and emotional outbursts with aggression. The genetic assessment revealed that the patient carries a de novo heterozygous frameshift insertion variant in the ARID1B c.3981dup (p.Glu1328ArgfsTer5), which are strongly associated with the typical clinical features of CSS patients. The test results of RT-qPCR showed that mRNA expression of the ARID1B gene in the proband was approximately 30% lower than that of the normal control in the family, suggesting that the variant had an impact on the gene function at the level of mRNA expression. The variant was pathogenic as assessed by ACMG guidelines. Analysis of protein interactions in the STRING online database revealed that the ARID1A protein interacts with the high myopia gene-related proteins FGFR3, ASXL1, ERBB3, and SOX4, whereas the ARID1A protein antagonizes the ARID1B protein. Therefore, in this paper, we are the first to report a de novo heterozygous frameshift insertion variant in the ARID1B gene causing CSS with excessive eoHM. Our study extends the genotypic and phenotypic spectrums for ARID1B-CSS and supplies evidence of significant association of eoHM with variant in ARID1B gene. As CSS has high genetic and phenotypic heterogeneity, our findings highlight the importance of molecular genetic testing and an interdisciplinary clinical diagnostic workup to avoid misdiagnosis as some disorders with similar manifestations of CSS.

Non-Specific Epileptic Activity, EEG, and Brain Imaging in Loss of Function Variants in SATB1: A New Case Report and Review of the Literature.

SATB1 (MIM #602075) is a relatively new gene reported only in recent years in association with neurodevelopmental disorders characterized by variable facial dysmorphisms, global developmental delay, poor or absent speech, altered electroencephalogram (EEG), and brain abnormalities on imaging. To date about thirty variants in forty-four patients/children have been described, with a heterogeneous spectrum of clinical manifestations. In the present study, we describe a new patient affected by mild intellectual disability, speech disorder, and non-specific abnormalities on EEG and neuroimaging. Family studies identified a new de novo frameshift variant c.1818delG (p.(Gln606Hisfs*101)) in SATB1. To better define genotype-phenotype associations in the different types of reported SATB1 variants, we reviewed clinical data from our patient and from the literature and compared manifestations (epileptic activity, EEG abnormalities and abnormal brain imaging) due to missense variants versus those attributable to loss-of-function/premature termination variants. Our analyses showed that the latter variants are associated with less severe, non-specific clinical features when compared with the more severe phenotypes due to missense variants. These findings provide new insights into SATB1-related disorders.

Variant-specific pathophysiological mechanisms of AFF3 differently influence transcriptome profiles.

BACKGROUND: We previously described the KINSSHIP syndrome, an autosomal dominant disorder associated with intellectual disability (ID), mesomelic dysplasia and horseshoe kidney, caused by de novo variants in the degron of AFF3. Mouse knock-ins and overexpression in zebrafish provided evidence for a dominant-negative mode of action, wherein an increased level of AFF3 resulted in pathological effects. METHODS: Evolutionary constraints suggest that other modes-of-inheritance could be at play. We challenged this hypothesis by screening ID cohorts for individuals with predicted-to-be damaging variants in AFF3. We used both animal and cellular models to assess the deleteriousness of the identified variants. RESULTS: We identified an individual with a KINSSHIP-like phenotype carrying a de novo partial duplication of AFF3 further strengthening the hypothesis that an increased level of AFF3 is pathological. We also detected seventeen individuals displaying a milder syndrome with either heterozygous Loss-of-Function (LoF) or biallelic missense variants in AFF3. Consistent with semi-dominance, we discovered three patients with homozygous LoF and one compound heterozygote for a LoF and a missense variant, who presented more severe phenotypes than their heterozygous parents. Matching zebrafish knockdowns exhibit neurological defects that could be rescued by expressing human AFF3 mRNA, confirming their association with the ablation of aff3. Conversely, some of the human AFF3 mRNAs carrying missense variants identified in affected individuals did not rescue these phenotypes. Overexpression of mutated AFF3 mRNAs in zebrafish embryos produced a significant increase of abnormal larvae compared to wild-type overexpression further demonstrating deleteriousness. To further assess the effect of AFF3 variation, we profiled the transcriptome of fibroblasts from affected individuals and engineered isogenic cells harboring + / + , KINSSHIP/KINSSHIP, LoF/ + , LoF/LoF or KINSSHIP/LoF AFF3 genotypes. The expression of more than a third of the AFF3 bound loci is modified in either the KINSSHIP/KINSSHIP or the LoF/LoF lines. While the same pathways are affected, only about one third of the differentially expressed genes are common to the homozygote datasets, indicating that AFF3 LoF and KINSSHIP variants largely modulate transcriptomes differently, e.g. the DNA repair pathway displayed opposite modulation. CONCLUSIONS: Our results and the high pleiotropy shown by variation at this locus suggest that minute changes in AFF3 function are deleterious.

[X-linked intellectual disability syndrome with macrocephaly due to BRWD3 gene deletion]. / Síndrome de discapacidad intelectual ligada a X con macrocefalia por deleción del gen BRWD3.

INTRODUCTION: Pathogenic variants in BRWD3 gene have been described as a rare cause of syndromic X-linked intellectual disability. Its phenotype shows neurodevelopmental delay with intellectual disability in all reported patients, facial dysmorphic features, macrocephaly, overgrowth and obesity. The great majority of cases yield point variants in the gene, only three large deletions including only the BRWD3 gene have been reported. The BRWD3 protein is an epigenetic reader that regulates chromatin remodeling. We report a boy with a compatible phenotype and a deletion including only this gene. CASE REPORT: Boy, without family and perinatal pathological background, with neurodevelopmental delay: psychomotor delay, speech delay and intellectual disability, macrocephaly (p > 99) and obesity. Phenotype with facial dysmorphic features: wide forehead, deep set eyes, bulbous nose, prominent ears and pointed chin. The array-CGH analysis showed a 586 kb deletion at Xq21.1 including only one gene with associated disorder, BRWD3. Afterwards, the deletion was also identified in his asymptomatic mother and sister. CONCLUSIONS: Our patient confirms that the haploinsufficiency due to BRWD3 deletion is a causal genetic mechanism of the BRWD3-related syndromic X-linked intellectual disability. It is important to recognize the phenotype for the diagnosis and follow up of the patients, and also to carry out the family genetic analysis in order to identify and give genetic counselling to the women who also have the genetic defect, because the majority of them are asymptomatic, as the mother and sister of our patient.

TITLE: Síndrome de discapacidad intelectual ligada a X con macrocefalia por deleción del gen BRWD3.Introducción. Variantes patógenas en el gen BRWD3 son la causa de un tipo poco frecuente de discapacidad intelectual sindrómica ligada a X. Su fenotipo se asocia a la alteración neuroconductual con discapacidad intelectual, dismorfia facial, macrocefalia, sobrecrecimiento y obesidad. La gran mayoría de los pacientes presenta variantes puntuales en el gen y sólo se han descrito tres casos con deleciones parciales que incluyen únicamente al gen BRWD3. Funcionalmente es un lector epigenético que regula la remodelación de la cromatina. Presentamos un varón con fenotipo compatible con una deleción que incluye sólo este gen asociado a patología. Caso clínico. Varón sin antecedentes familiares ni perinatales de interés con alteración en el neurodesarrollo: retraso psicomotor, retraso del lenguaje y discapacidad cognitiva, macrocefalia (p > 99) y obesidad. Fenotipo con dismorfia facial: frente amplia, ojos hundidos, nariz bulbosa, pabellones auriculares despegados y mentón afilado. Array de hibridación genómica comparada con deleción de 586 kb en Xq21.1, que incluye un único gen asociado a la patología, BRWD3. Posteriormente se realizó un estudio a la madre y a la hermana, asintomáticas, y ambas portan la deleción. Conclusiones. Nuestro caso confirma que la haploinsuficiencia debida a la deleción del gen BRWD3 es un mecanismo genético causal de la discapacidad intelectual sindrómica ligada a X asociada al gen BRWD3. Es importante reconocer el fenotipo para el diagnóstico y el seguimiento, así como la realización del estudio familiar para asesoramiento genético a las mujeres que porten la alteración, puesto que en la mayoría de los casos son asintomáticas, como la madre y la hermana de este paciente.

Could the 14q23.2 microdeletion or AKAP5 haploinsufficiency be a potential cause of intellectual disability?

Intellectual disability is characterized by impairment in at least two of the following areas: social skills, communication skills, self-care tasks, and academic skills. These impairments are evaluated in relation to the expected standards based on the individual's age and cultural levels. Additionally, intellectual disability is typically defined by a measurable level of intellectual functioning, represented by an intelligence quotients core of 70 or below. Autism spectrum disorder is a developmental disability resulting from differences in the brain, often characterized by problems in social communication and interaction, and limited or repetitive behaviors or interests. Hereditary spherocytosis is a disease characterized by anemia, jaundice, and splenomegaly as a result of increased tendency to hemolysis with morphological transformation of erythrocytes from biconcave disc-shaped cells with central pallor to spherocytes lacking central pallor due to hereditary injury of cellular membrane proteins. An 11-year-old female patient was referred to Pediatric Genetics Subdivision due to the presence of growth retardation and a diagnosis of hereditary spherocytosis. Since she also had dysmorphic facial features, such as frontal bossing, broad and prominent forehead, tubular nasal structure, and thin vermillion, genetic tests were performed. Chromosomal microarray analysis revealed a 2.5 Mb deletion in the 14q23.2q23.3 region. Deletion was also identified in the same region in her father, who had the same phenotypic characteristics, including hereditary spherocytosis and learning difficulties. We propose that the PLEKHG3 and AKAP5 genes, which are located in this region, may contribute to the development of intellectual disability.

Genetic analysis of a child with severe intellectual disability caused by a novel variant in the FERM domain of the FRMPD4 protein.

Intellectual developmental disorder, X-linked 104 (XLID104), caused by the FRMPD4 gene variant, is a rare X-linked genetic disease that primarily manifests as intellectual disability (ID) and language delay, and may be accompanied by behavioural abnormalities. Currently, only 11 patients from four families have been reported to carry FRMPD4 gene variants. Here, we report a rare case of a Chinese patient with XLID104 who was presented with severe ID and language impairment. Genetic testing results showed that the patient had a novel hemizygous variant on FRMPD4 inherited from the heterozygous variant NM_001368397: c.1772A>C (p.Glu591Ala) carried by his mother. To our knowledge, this variant has not been reported previously. Western blot results for the recombinant plasmid constructed in vitro indicated that the expression of the mutant protein may be reduced. Using molecular dynamics simulations, we predicted that the mutant protein may affect the interaction of the FRMPD4 protein with DLG4. In this study, we expand the spectrum of FRMPD4 variants and suggest that the clinical awareness of the genetic diagnosis of nonsyndromic ID should be strengthened.

Increasing histone acetylation improves sociability and restores learning and memory in KAT6B-haploinsufficient mice.

Mutations in genes encoding chromatin modifiers are enriched among mutations causing intellectual disability. The continuing development of the brain postnatally, coupled with the inherent reversibility of chromatin modifications, may afford an opportunity for therapeutic intervention following a genetic diagnosis. Development of treatments requires an understanding of protein function and models of the disease. Here, we provide a mouse model of Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) (OMIM 603736) and demonstrate proof-of-principle efficacy of postnatal treatment. SBBYSS results from heterozygous mutations in the KAT6B (MYST4/MORF/QFK) gene and is characterized by intellectual disability and autism-like behaviors. Using human cells carrying SBBYSS-specific KAT6B mutations and Kat6b heterozygous mice (Kat6b+/-), we showed that KAT6B deficiency caused a reduction in histone H3 lysine 9 acetylation. Kat6b+/- mice displayed learning, memory, and social deficits, mirroring SBBYSS individuals. Treatment with a histone deacetylase inhibitor, valproic acid, or an acetyl donor, acetyl-carnitine (ALCAR), elevated histone acetylation levels in the human cells with SBBYSS mutations and in brain and blood cells of Kat6b+/- mice and partially reversed gene expression changes in Kat6b+/- cortical neurons. Both compounds improved sociability in Kat6b+/- mice, and ALCAR treatment restored learning and memory. These data suggest that a subset of SBBYSS individuals may benefit from postnatal therapeutic interventions.