A novel variant in NSUN2 causes intellectual disability in a Chinese family.

NSUN2-intellectual disability syndrome, also known as intellectual disability type 5 (MRT5), is an autosomal recessive disorder that is characterized by intellectual disability (ID), postnatal growth retardation, dysmorphic facies, microcephaly, short stature, developmental delay, language impairment and other congenital abnormalities. The disease is caused by mutations in the NSUN2 gene, which encodes a tRNA cytosine methyltransferase that has an important role in spindle assembly during mitosis and chromosome segregation. In this study, we recruited a family that had two individuals with ID. Whole exome sequencing was performed to identify a homozygous frameshift variant (c.1171_1175delACCAT(p.Thr391fs*18*)) in NSUN2 (NM_017755.5) in the proband. The varint was confirmed as segregating in his affected brother and his parents by Sanger sequencing. The individuals that we described showed a similar dysmorphology profile to that associated with MRT5. To analyze the correlations between genotypes of NSUN2 and phenotypes of individuals with ID, we examined 17 variants and the associated phenotypes from 32 ID individuals in current and previous studies. We concluded that mutations in NSUN2 cause a wide range of phenotypic defects. Although some clinical manifestations were highly variable, the core phenotypes associated with NSUN2 mutations were dysmorphic facies, microcephaly, short stature, ID, growth restriction, language impairment, hypotonia and delayed puberty. Our study expands the genetic spectrum of NSUN2 mutations and helps to further define the genotype-phenotype correlations in MRT5.

Malformations of cortical development: Fetal imaging and genetics.

BACKGROUND: Malformations of cortical development (MCD) are a group of congenital disorders characterized by structural abnormalities in the brain cortex. The clinical manifestations include refractory epilepsy, mental retardation, and cognitive impairment. Genetic factors play a key role in the etiology of MCD. Currently, there is no curative treatment for MCD. Phenotypes such as epilepsy and cerebral palsy cannot be observed in the fetus. Therefore, the diagnosis of MCD is typically based on fetal brain magnetic resonance imaging (MRI), ultrasound, or genetic testing. The recent advances in neuroimaging have enabled the in-utero diagnosis of MCD using fetal ultrasound or MRI. METHODS: The present study retrospectively reviewed 32 cases of fetal MCD diagnosed by ultrasound or MRI. Then, the chromosome karyotype analysis, single nucleotide polymorphism array or copy number variation sequencing, and whole-exome sequencing (WES) findings were presented. RESULTS: Pathogenic copy number variants (CNVs) or single-nucleotide variants (SNVs) were detected in 22 fetuses (three pathogenic CNVs [9.4%, 3/32] and 19 SNVs [59.4%, 19/32]), corresponding to a total detection rate of 68.8% (22/32). CONCLUSION: The results suggest that genetic testing, especially WES, should be performed for fetal MCD, in order to evaluate the outcomes and prognosis, and predict the risk of recurrence in future pregnancies.

A nonsense CC2D1A variant is associated with congenital anomalies, motor delay, hypotonia, and slight deformities.

Background: Autosomal recessive intellectual developmental disorder-3 is caused by homozygous or compound heterozygous mutations in the CC2D1A gene. The disorder is characterized by intellectual disability (ID) and autism spectrum disorder (ASD). To date, 39 patients from 17 families with CC2D1A -related disorders have been reported worldwide, in whom only six pathogenic or likely pathogenic loss-of-function variants and three variants of uncertain significance (VUS) in the CC2D1A gene have been identified in these patients. Methods: We described a patient with ID from a non-consanguineous Chinese family and whole-exome sequencing (WES) was used to identify the causative gene. Results: The patient presented with severe ID and ASD, speech impairment, motor delay, hypotonia, slight facial anomalies, and finger deformities. Threatened abortion and abnormal fetal movements occurred during pregnancy with the proband but not his older healthy sister. WES analysis identified a homozygous nonsense variant, c.736C > T (p.Gln246Ter), in the CC2D1A gene. In addition, six novel likely pathogenic CC2D1A variants were identified by a retrospective review of the in-house database. Conclusions: This study expands the genetic and clinical spectra of CC2D1A-associated disorders, and may aid in increasing awareness of this rare condition. Our findings have provided new insights into the clinical heterogeneity of the disease and further phenotype-genotype correlation, which could help to offer scope for more accurate genetic testing and counseling to affected families.

Clinical and genetic analysis of trichohepatoneurodevelopmental syndrome caused by a CCDC47 variant.

Trichohepatoneurodevelopmental syndrome is an extremely uncommon autosomal recessive disorder resulting from variants in the CCDC47 gene, which encodes a Ca2+-binding endoplasmic reticulum (ER) transmembrane protein. To date, only four patients with CCDC47 deficiency have been reported, all of them with homozygous truncating CCDC47 variants. For this study, a Chinese family was recruited, which included a patient diagnosed with trichohepatoneurodevelopmental syndrome. Whole exome sequencing (WES) identified the proband's novel homozygous CCDC47 variation (NM_020198: c.634C > T(p.Arg212*). The variant was confirmed to be segregating in the proband and her unaffected relatives through Sanger sequencing. The patient described exhibited a clinical phenotype similar to that of patients with the CCDC47 variant. Compared to reported cases with CCDC47 pathogenic variants, our patients showed a novel complication of hearing impairment. In addition, brain abnormalities, small feet, bilateral hip dislocation, hip dysplasia, overlapping toes, pectus excavatum, scoliosis and narrow chest were not observed in our patient. We also examined five different variations and their corresponding phenotypes from five patients, both in current and previous research. Although some clinical manifestations of trichohepatoneurodevelopmental syndrome were highly variable, the most common phenotypes observed in these patients include microcephaly, profound intellectual disability, severe global development delay, pronounced growth restriction, hypotonia, woolly hair, facial dysmorphism, respiratory and visual abnormalities, gastrointestinal abnormalities, liver dysfunction, pruritus, skeletal and limb abnormalities, congenital heart defects and immunodeficiency. The present report is the first of a Chinese infant with homozygous variant in the CCDC47 gene. We expanded the genetic and phenotypic spectrum associated with trichohepatoneurodevelopmental syndrome.

Single Cell Map of Human Azoospermia Testis Caused by Cyclophosphamide Chemotherapy.

Chemotherapeutic drugs will affect the process of spermatogenesis. However, most current studies on the effects of chemotherapeutic drugs on spermatogenesis are based on mouse models, with a shortage of human body evidence. In addition, the mechanism of chemotherapeutic drugs causing spermatogenesis disorder is not clear. Therefore, we have collected the testicular tissues of an inguinal-lipoma patient whose testes were resected after chemotherapy and a patient who had normal spermatogenesis disorder and underwent single-nucleus RNA sequencing (snRNA-Seq). After quality control, we obtained a total of 27,957 high-quality cells, including 18,612 normal cells and 9,345 drug-treated cells, which were all used in analyzing the mechanism of chemotherapeutic drugs causing spermatogenesis disorder. This study has provided data resources and references for exploring the mechanism of chemotherapeutic drugs causing spermatogenesis disorder with the insight of protecting the spermatogenic abilities of male tumor patients receiving chemotherapy.

Upregulation of CALD1 predicted a poor prognosis for platinum-treated ovarian cancer and revealed it as a potential therapeutic resistance target.

BACKGROUND: Ovarian cancer (OC) has the worst prognosis among gynecological malignancies, most of which are found to be in advanced stage. Cell reduction surgery based on platinum-based chemotherapy is the current standard of treatment for OC, but patients are prone to relapse and develop drug resistance. The objective of this study was to identify a specific molecular target responsible for platinum chemotherapy resistance in OC. RESULTS: We screened the protein-coding gene Caldesmon (CALD1), expressed in cisplatin-resistant OC cells in vitro. The prognostic value of CALD1 was evaluated using survival curve analysis in OC patients treated with platinum therapy. The diagnostic value of CALD1 was verified by drawing a Receiver Operating Characteristic (ROC) curve using clinical samples from OC patients. This study analyzed data from various databases including Gene Expression Omnibus (GEO), Human Protein Atlas (HPA), The Cancer Cell Line Encyclopedia (CCLE), The Cancer Genome Atlas (TCGA), GEPIA 2, UALCAN, Kaplan-Meier (KM) plotter, LinkedOmics database, and String. Different expression genes (DEGs) between cisplatin-sensitive and cisplatin-resistant cells were acquired respectively from 5 different datasets of GEO. CALD1 was selected as a common gene from 5 groups DEGs. Online data analysis of HPA and CCLE showed that CALD1 was highly expressed in both normal ovarian tissue and OC. In TCGA database, high expression of CALD1 was associated with disease stage and venous invasion in OC. Patients with high CALD1 expression levels had a worse prognosis under platinum drug intervention, according to Kaplan-Meier (KM) plotter analysis. Analysis of clinical sample data from GEO showed that CALD1 had superior diagnostic value in distinguishing patients with platinum "resistant" and platinum "sensitive" (AUC = 0.816), as well as patients with worse progression-free survival (AUC = 0.741), and those with primary and omental metastases (AUC = 0.811) in ovarian tumor. At last, CYR61 was identified as a potential predictive molecule that may play an important role alongside CALD1 in the development of platinum resistance in OC. CONCLUSIONS: CALD1, as a member of cytoskeletal protein, was associated with poor prognosis of platinum resistance in OC, and could be used as a target protein for mechanism study of platinum resistance in OC.

Novel germline variants in KMT2C in Chinese patients with Kleefstra syndrome-2.

Kleefstra syndrome (KLEFS) refers to a rare inherited neurodevelopmental disorder characterized by intellectual disability (ID), language and motor delays, behavioral abnormalities, abnormal facial appearance, and other variable clinical features. KLEFS is subdivided into two subtypes: Kleefstra syndrome-1 (KLEFS1, OMIM: 610253), caused by a heterozygous microdeletion encompassing the Euchromatic Histone Lysine Methyltransferase 1 (EHMT1) gene on chromosome 9q34.3 or pathogenic variants in the EHMT1 gene, and Kleefstra syndrome-2 (KLEFS2, OMIM: 617768), caused by pathogenic variants in the KMT2C gene. More than 100 cases of KLEFS1 have been reported with pathogenic variants in the EHMT1 gene. However, only 13 patients with KLEFS2 have been reported to date. In the present study, five unrelated Chinese patients were diagnosed with KLEFS2 caused by KMT2C variants through whole-exome sequencing (WES). We identified five different variants of the KMT2C gene in these patients: c.9166C>T (p.Gln3056*), c.9232_9247delCAGCGATCAGAACCGT (p.Gln3078fs*13), c.5068dupA (p.Arg1690fs*10), c.10815_10819delAAGAA (p.Lys3605fs*7), and c.6911_6912insA (p.Met2304fs*8). All five patients had a clinical profile similar to that of patients with KLEFS2. To analyze the correlation between the genotype and phenotype of KLEFS2, we examined 18 variants and their associated phenotypes in 18 patients with KLEFS2. Patients carrying KMT2C variants presented with a wide range of phenotypic defects and an extremely variable phenotype. We concluded that the core phenotypes associated with KMT2C variants were intellectual disability, facial dysmorphisms, language and motor delays, behavioral abnormalities, hypotonia, short stature, and weight loss. Additionally, sex may be one factor influencing the outcome. Our findings expand the phenotypic and genetic spectrum of KLEFS2 and help to clarify the genotype-phenotype correlation.

Novel variants in TNRC6B cause global developmental delay with speech and behavioral abnormalities, short stature, low body weight, café-au-lait spots, and metabolic abnormality.

BACKGROUND: TNRC6B deficiency syndrome, also known as global developmental delay with speech and behavioral abnormalities (MIM 619243), is a rare autosomal dominant genetic disease mainly characterized by facial dysmorphism, developmental delay/intellectual disability (DD/ID), speech and language delay, fine and motor delay, attention deficit and hyperactivity disorder (ADHD), and variable behavioral abnormalities. It is caused by heterozygous variant in the TNRC6B gene (NM_001162501.2, MIM 610740), which encodes the trinucleotide repeat-containing adaptor 6B protein. METHODS: In this study, two Chinese patients with TNRC6B deficiency syndrome were recruited, and genomic DNA extraction from peripheral blood leukocytes of these parents and their family members was extracted for whole-exome sequencing and Sanger sequencing. RESULTS: Here, we report two unrelated Chinese patients diagnosed with TNRC6B deficiency syndrome caused by novel de novo likely pathogenic or pathogenic TNRC6B variants c.335C>T (p.Pro112Leu) and c.1632delC (p.Leu546fs*63), which expands the genetic spectrum of TNRC6B deficiency syndrome. The clinical features of the patients were DD/ID, delayed speech, ADHD, behavioral abnormalities, short stature, low body weight, café-au-lait spots, metabolic abnormalities, and facial dysmorphism including coarse facial features, sparse hair, frontal bossing, hypertelorism, amblyopia, strabismus, and downslanted palpebral fissures, which expands the phenotype spectrum associated with TNRC6B deficiency syndrome. CONCLUSION: This study expands the genotypic and phenotypic spectrum of TNRC6B deficiency syndrome. Our findings indicate that patients with TNRC6B deficiency syndrome should be monitored for growth and metabolic problems and therapeutic strategies should be developed to address these problems. Our report also suggests the clinical diversity of TNRC6B deficiency syndrome.

Compound heterozygous WDR19 variants associated with nephronophthisis, Caroli disease, refractory epilepsy and congenital bilateral central blindness: Case report.

The WDR19 gene has been reported to be involved in nephronophthisis-related ciliopathies such as isolated nephronophthisis 13 (NPHP13), Sensenbrenner syndrome, Jeune syndrome, Senior-Loken syndrome, Caroli disease, retinitis pigmentosa and Asthenoteratospermia. In the present study, we provided the detailed clinical characteristics and genetic analysis of a patient with four variants in WDR19 and TG, reviewed a comprehensive mutation analysis in the WDR19-related ciliopathies, discussed the relationship between genotype and phenotype, and compared the allele frequencies (AFs) of WDR19 variants depending on the ethnic background. We used whole-exome sequencing (WES) combined with bioinformatics analysis to investigate the genetic variants of a 3-year-old boy with common features of WDR19-associated NPHP13 and Caroli disease, bilateral central blindness, refractory epilepsy, and elevated thyroid stimulating hormone. A novel splice-donor variant, c.98+1G > C, and a recurrent missense variant, c.3533G > A, were identified in the WDR19 gene. We used effective mRNA analysis to verify the effects on pre-mRNA processing and to assess the pathogenicity of the splice-site variant. The patient also harbored compound heterozygous variants of the TG gene (c.4889A > G, c.274+2T > G). Of note, using a review of an in-house database, we identified four additional likely pathogenic WDR19 variants and estimated the overall AF of WDR19 mutations to be 0.0025 in the southern Chinese population. Our findings have expanded the allelic spectrum of mutations in the WDR19 gene and broadened the clinical phenotype spectrum of WDR19-related ciliopathies. The results have also provided new insights into the clinical heterogeneity of the disorder, which would be useful in accurate genetic counseling for affected individuals and carrier screening in a general population.

A genetic variant in the MAST1 gene is associated with mega-corpus-callosum syndrome with hypoplastic cerebellar vermis, in a fetus.

BACKGROUND: Mega-corpus-callosum syndrome with cerebellar hypoplasia and cortical malformations is a rare neurological disorder that is associated with typical clinical and imaging features. The syndrome is caused by pathogenic variants in the MAST1 gene, which encodes a microtubule-associated protein that is predominantly expressed in postmitotic neurons in the developing nervous system. METHODS: Fetal DNA from umbilical cord blood samples and genomic DNA from peripheral blood lymphocytes were subjected to whole-exome sequencing. The potential causative variants were verified by Sanger sequencing. RESULTS: A 26-year-old primigravid woman was referred to our prenatal center at 25 weeks of gestation due to abnormal ultrasound findings in the brain of the fetus. The brain abnormalities included wide cavum septum pellucidum, shallow and incomplete bilateral lateral fissure cistern, bilateral dilated lateral ventricles, hyperplastic corpus callosum, lissencephaly, and cortical dysplasia. No obvious abnormalities were observed in the brainstem or cerebellum hemispheres, but the cerebellum vermis was small. Whole-exome sequencing identified a de novo, heterozygous missense variant, c.695T>C(p.Leu232Pro), in the MAST1 gene and a genetic diagnosis of mega-corpus-callosum syndrome was considered. CONCLUSION: This study is the first prenatal case of MAST1-related disorder reported in the Chinese population and has expanded the mutation spectrum of the MAST1 gene.

Clinical features and molecular genetic investigation of infantile-onset ascending hereditary spastic paralysis (IAHSP) in two Chinese siblings caused by a novel splice site ALS2 variation.

OBJECTIVE: ALS2-related disorder involves retrograde degeneration of the upper motor neurons of the pyramidal tracts, among which autosomal recessive Infantile-onset ascending hereditary spastic paralysis (IAHSP) is a rare phenotype. In this study, we gathered clinical data from two Chinese siblings who were affected by IAHSP. Our aim was to assess the potential pathogenicity of the identified variants and analyze their clinical and genetic characteristics. METHOD: Here, Whole-exome sequencing (WES) was performed on proband to identify the candidate variants. Subsequently, Sanger sequencing was used to verify identified candidate variants and to assess co-segregation among available family members. Utilizing both silico prediction and 3D protein modeling, an analysis was conducted to evaluate the potential functional implications of the variants on the encoded protein, and minigene assays were performed to unravel the effect of the variants on the cleavage of pre-mRNA. RESULTS: Both patients were characterized by slurred speech, astasia, inability to walk, scoliosis, lower limb hypertonia, ankle clonus, contracture of joint, foot pronation and no psychomotor retardation was found. Genetic analysis revealed a novel homozygous variant of ALS2, c.1815G > T(p.Lys605Asn) in two Chinese siblings. To our knowledge, it is the first confirmed case of a likely pathogenic variant leading to IAHSP in a Chinese patient. CONCLUSION: This study broadens the range of ALS2 variants and has practical implications for prenatal and postnatal screening of IAHSR. Symptom-based diagnosis of IAHSP is frequently difficult for medical practitioners. WES can be a beneficial resource to identify a particular disorder when the diagnosis cannot be determined from the symptoms alone.

Phenotypic and genotypic characterization of NPRL3-related epilepsy: Two case reports and literature review.

Nitrogen permease regulator-like 3 (NPRL3) has been reported to play a role in seizure onset. The principal manifestation of NPRL3-related epilepsy is a range of epilepsy-associated syndromes, such as familial focal epilepsy with variable foci (FFEVF), sleep-related hypermotor epilepsy (SHE), and temporal lobe epilepsy (TLE). The association between phenotype and genotype of NPRL3 mutations remains inadequately described. This study aimed to explore the phenotypic and genotypic spectra of NPRL3-related epilepsy. We reported two novel NPRL3 variants in two unrelated epilepsy cases, including a nonsense (c.1174C > T, p.Gln392*) and a missense variant (c.1322C > T, p.Thr441Met). Following a review of the literature, a total of 116 cases of NPRL3-related epilepsy were assessed, mostly with nonsense and frameshift mutations. Our findings suggest that patients harboring various NPRL3 variants exhibit variable clinical manifestations. In addition, it may be worthwhile to consider the existence of NPRL3 mutations in epilepsy patients with a family history. This study provides useful information for the treatment and prognosis by expanding the phenotypic and genotypic spectrum of NPRL3-related epilepsy. PLAIN LANGUAGE SUMMARY: This study expands the phenotypic and genotypic spectra of NPRL3-related epilepsy by reporting two cases with different novel variants. Following a review of the literature, it was observed that patients harboring various NPRL3 variants exhibited a variability of clinical manifestations. Also, patients carrying nonsense mutations are frequently prone to drug resistance and other severe comorbidities such as developmental delay, but more cases need to be collected to confirm these findings.

Clinical and molecular analysis of Guangxi patients with Kabuki syndrome and KMT2D mutations.

Kabuki syndrome (KS) is a multiple congenital anomaly syndrome that is characterized by postnatal growth deficiency, hypotonia, short stature, mild-to-moderate intellectual disability, skeletal abnormalities, persistence of fetal fingertip pads, and distinct facial appearance. It is mainly caused by pathogenic/likely pathogenic variants in the KMT2D or KDM6A genes. Here, we described the clinical features of nine sporadic KS patients with considerable phenotypic heterogeneity. In addition to intellectual disability and short stature, our patients presented with a high prevalence of motor retardation and recurrent otitis media. We recommended that KS should be strongly considered in patients with motor delay, short stature, intellectual disability, language disorder and facial deformities. Nine KMT2D variants, four of which were novel, were identified by whole-exome sequencing. The variants included five nonsense variants, two frameshift variants, one missense variant, and one non-canonical splice site variant. In addition, we reviewed the mutation types of the pathogenic KMT2D variants in the ClinVar database. We also indicated that effective mRNA analysis, using biological materials from patients, is helpful in classifying the pathogenicity of atypical splice site variants. Pedigree segregation analysis may also provide valuable information for pathogenicity classification of novel missense variants. These findings extended the mutation spectrum of KMT2D and provided new insights into the understanding of genotype-phenotype correlations, which are helpful for accurate genetic counseling and treatment optimization.

The function and mechanism of lactate and lactylation in tumor metabolism and microenvironment.

Lactate is an end product of glycolysis. Owing to the lactate shuttle concept introduced in the early 1980s, increasing researchers indicate lactate as a critical energy source for mitochondrial respiration and as a precursor of gluconeogenesis. Lactate also acts as a multifunctional signaling molecule through receptors expressed in various cells, resulting in diverse biological consequences including decreased lipolysis, immune regulation, and anti-inflammation wound healing, and enhanced exercise performance in association with the gut microbiome. Furthermore, increasing evidence reveals that lactate contributes to epigenetic gene regulation by lactylating lysine residues of histones, which accounts for its key role in immune modulation and maintenance of homeostasis. Here, we summarize the function and mechanism of lactate and lactylation in tumor metabolism and microenvironment.

Early onset horizontal gaze palsy and progressive scoliosis due to a noncanonical splicing-site variant and a missense variant in the ROBO3 gene.

BACKGROUND: Homozygous or compound heterozygous ROBO3 gene mutations cause horizontal gaze palsy with progressive scoliosis (HGPPS). This is an autosomal recessive disorder that is characterized by congenital absence or severe restriction of horizontal gaze and progressive scoliosis. To date, almost 100 patients with HGPPS have been reported and 55 ROBO3 mutations have been identified. METHODS: We described an HGPPS patient and performed whole-exome sequencing (WES) to identify the causative gene. RESULTS: We identified a missense variant and a splice-site variant in the ROBO3 gene in the proband. Sanger sequencing of cDNA revealed the presence of an aberrant transcript with retention of 700 bp from intron 17, which was caused by a variation in the noncanonical splicing site. We identified five additional ROBO3 variants, which were likely pathogenic, and estimated the overall allele frequency in the southern Chinese population to be 9.44 × 10-4 , by a review of our in-house database. CONCLUSION: This study has broadened the mutation spectrum of the ROBO3 gene and has expanded our knowledge of variants in noncanonical splicing sites. The results could help to provide more accurate genetic counseling to affected families and prospective couples. We suggest that the ROBO3 gene should be included in the local screening strategy.

Novel compound heterozygous variants in the RPL3L gene causing dilated cardiomyopathy type-2D: a case report and literature review.

BACKGROUND: Dilated cardiomyopathy type-2D (CMD2D) is a rare heart disease causing a severe cardiomyopathy with neonatal onset and rapid progression to cardiac decompensation and death in untreated patients. CMD2D is an autosomal recessive disease resulting from variants in the RPL3L gene, which encodes the 60 S ribosomal protein exclusively expressed in skeletal and cardiac muscle and plays an essential role in myoblast growth and fusion. Previous reports have only associated CMD2D with a small duplication and seven nucleotide substitution in the RPL3L gene. CASE PRESENTATION: In this study, we report the case of a 31 days old Chinese infant patient with severe dilated cardiomyopathy (DCM) and rapid decompensation along with other cardiac malformations. In addition to previously reported clinical features, the patient showed the previously unreported complication of occasional premature atrial contractions and a first-degree atrioventricular block. Whole-exome sequencing (WES) revealed compound heterozygous variants (c.80G > A (p.Gly27Asp) and c.1074dupA (p.Ala359fs*6)) in RPL3L (NM_005061.3). The latter novel variant may result in the absence of protein production with a significant decrease in mRNA level, suggesting it is a loss-of-function mutation. CONCLUSIONS: This is the first case report of RPL3L-associated neonatal dilated cardiomyopathy in China. The molecular confirmation of the patient expands the genetic spectrum of CMD2D, and the clinical manifestation of CMD2D in the patient provides additional clinical information regarding this disease.

Haplotype-specific MAPK3 expression in 16p11.2 deletion contributes to variable neurodevelopment.

Recurrent proximal 16p11.2 deletion (16p11.2del) is a risk factor for diverse neurodevelopmental disorders with incomplete penetrance and variable expressivity. Although investigation with human induced pluripotent stem cell models has confirmed disruption of neuronal development in 16p11.2del neuronal cells, which genes are responsible for abnormal cellular phenotypes and what determines the penetrance of neurodevelopmental abnormalities are unknown. We performed haplotype phasing of the 16p11.2 region in a 16p11.2del neurodevelopmental disorders cohort and generated human induced pluripotent stem cells for two 16p11.2del families with distinct residual haplotypes and variable neurodevelopmental disorder phenotypes. Using transcriptomic profiles and cellular phenotypes of the human induced pluripotent stem cell-differentiated cortex neuronal cells, we revealed MAPK3 to be a contributor to dysfunction in multiple pathways related to early neuronal development, with altered soma and electrophysiological properties in mature neuronal cells. Notably, MAPK3 expression in 16p11.2del neuronal cells varied on the basis of a 132 kb 58 single nucleotide polymorphism (SNP) residual haplotype, with the version composed entirely of minor alleles associated with reduced MAPK3 expression. Ten SNPs on the residual haplotype were mapped to enhancers of MAPK3. We functionally validated six of these SNPs by luciferase assay, implicating them in the residual haplotype-specific differences in MAPK3 expression via cis-regulation. Finally, the analysis of three different cohorts of 16p11.2del subjects showed that this minor residual haplotype is associated with neurodevelopmental disorder phenotypes in 16p11.2del carriers.

Phenotypic Spectrum of Trisomy 18 Mosaicism: a New Patient and Literature Review.

BACKGROUND: Trisomy 18 syndrome, also called Edwards syndrome, is the second most common autosomal trisomy after trisomy 21 that is caused by the presence of an extra copy of chromosome 18. Approximately 50% of infants with trisomy 18 cannot survive for more than 1 week and about 5 - 10% of children die within 1 year after birth. The aim of this study is to describe a 4-year-old female patient of mosaic trisomy 18 with normal prenatal ultrasound findings and maternal serum markers and to investigate the relationship between the percentage of trisomic cells and the major clinical phenotypes combined with other nine patients through a review of the literature. METHODS: The patient's peripheral blood was examined by cytogenetic G-banding technique. RESULTS: The cytogenetics results reported following the ISCN 2020 guideline as mos 47,XX,+18[87]/46,XX[13]. CONCLUSIONS: There is little correlation between various phenotypes of mosaic trisomy 18 and the percentage of trisomy cells in the patient's peripheral leukocytes. Although most of fetuses with mosaic trisomy 18 have abnormal ultrasound findings, it is necessary to highlight the possibility of normal findings during the pregnancy.

Characteristics of Allan-Herndon-Dudley Syndrome in Chinese children: Identification of two novel pathogenic variants of the SLC16A2 gene.

Objective: The aim of this study was to identify causative variants associated with Allan-Herndon-Dudley syndrome (AHDS) in two unrelated Chinese families, and to determine their potential pathogenicity. We also summarized the core clinical symptoms of AHDS by reviewing the related literature. Methods: Genomic DNA was isolated from the peripheral blood of AHDS patients and their family members. Whole exome sequencing (WES) was performed on the proband from each family to identify the candidate variants. Subsequently, Sanger sequencing was used to verify the identified candidate variants and to assess co-segregation among the available family members. In silico prediction combined with 3D protein modeling was conducted to predict the functional effects of the variants on the encoded protein. Results: Two novel hemizygous variants of SLC16A2, c.1111_1112insGTCTTGT (Gly375fs*6) and c.942delA (Val315fs*28), were detected in two patients. We compared the clinical symptoms of the patients with all patients with AHDS reported in China and those reported in the literature. While both our patients presented symptoms mostly consistent with AHDS, Patient 1 had no abnormal brain structure and thyroid function, and yet showed other symptoms including lactic aciduria, conjunctival hyperemia, vomiting, laryngeal stridor, low immunoglobulin and iron levels. Conclusions: This study expands the mutation spectrum of AHDS and has clinical value for variant-based prenatal and postnatal screening for this condition. Doctors often have difficulty identifying AHDS by using clinical symptoms. WES can help to identify specific disorder when diagnosis cannot be made based on symptoms alone.

Novel Synonymous and Frameshift Variants in the TRIP12 Gene Identified in 2 Chinese Patients With Intellectual Disability.

Background and Objectives: Clark-Baraitser syndrome is characterized by intellectual disability with or without autism spectrum disorders, speech delay, motor delay, behavioral abnormalities, and facial dysmorphism. It is caused by a heterozygous pathogenic variant in the thyroid hormone receptor interactor 12 (TRIP12) gene. However, loss of function and haploinsufficiency are the pathogenic mechanisms behind the TRIP12-related disorder. Methods: We conducted an exome sequencing analysis for 2 unrelated patients with moderate intellectual disability, speech delay, and motor delay. Results: We identified 2 de novo TRIP12 mutations in these 2 patients. One patient had a frameshift duplication, whereas the other had a synonymous variant. Both patients presented with common features of the syndrome, but clinical heterogeneity has been also observed between them. For the synonymous variant, reverse transcription PCR in RNA extracted from leukocytes demonstrated the presence of a truncated messenger RNA (mRNA) transcript that skipped exon 12. This transcript escapes degradation at the mRNA level. To assess the effect of the synonymous substitute on TRIP12 proteolytic activity, the expression of 9 known responsive genes at the mRNA level was measured, of which 3 genes were upregulated at least 2-fold in the patient. Discussion: We reported 2 patients with Clark-Baraitser syndrome caused by novel synonymous and frameshift variants in the TRIP12 gene, and our study expands the mutation spectrum of the TRIP12 gene. This study will help to improve our understanding of variable phenotypic presentations in TRIP12-related disorders.