Search

SETD2 belongs to the family of histone methyltransferase proteins and has been associated with three nosologically distinct entities with different clinical and molecular features: Luscan–Lumish syndrome (LLS), intellectual developmental disorder, autosomal dominant 70 (MRD70), and Rabin–Pappas syndrome (RAPAS). LLS [MIM #616831] is an overgrowth disorder with multisystem involvement including intellectual disability, speech delay, autism spectrum disorder (ASD), macrocephaly, tall stature, and motor delay. RAPAS [MIM #6201551] is a recently reported multisystemic disorder characterized by severely impaired global and intellectual development, hypotonia, feeding difficulties with failure to thrive, microcephaly, and dysmorphic facial features. Other neurologic findings may include seizures, hearing loss, ophthalmologic defects, and brain imaging abnormalities. There is variable involvement of other organ systems, including skeletal, genitourinary, cardiac, and potentially endocrine. Three patients who carried the missense variant p.Arg1740Gln in SETD2 were reported with a moderately impaired intellectual disability, speech difficulties, and behavioral abnormalities. More variable findings included hypotonia and dysmorphic features. Due to the differences with the two previous phenotypes, this association was then named intellectual developmental disorder, autosomal dominant 70 [MIM 620157]. These three disorders seem to be allelic and are caused either by loss-of-function, gain-of-function, or missense variants in the SETD2 gene. Here we describe 18 new patients with variants in SETD2, most of them with the LLS phenotype, and reviewed 33 additional patients with variants in SETD2 that have been previously reported in the scientific literature. This article offers an expansion of the number of reported individuals with LLS and highlights the clinical features and the similarities and differences among the three phenotypes associated with SETD2.

The endless debates on Sophocles' Antigone reflect different analytical perspectives as to the multiple and concurrent dualities intertwined in the drama, like legality and legitimacy, lawfulness and morality, expediency and tradition, humans and the divine. Still, subjective perspectives notwithstanding, a conceptually and aesthetically prevalent duality in the Antigone pertains to the head-on conflict between (king Creon's) material power and (Antigone's) moral strength: Adult Creon's reasoning for enforcing his deadly kingly edict on adolescent Antigone is well founded with respect to the imperative need to maintain law and order in his dominion, as a necessary condition for reinstituting socio-political stability and ensuring the security and independence of his polis, especially in extreme conditions of civil warfare; nevertheless his aesthetically hubristic exertion of power leads the monarch's own family to self-destruction. In this mythological twist of fate, the Antigone brings to the fore artistically (and barely disputably) the limitations of the so-called right of the strongest, because the strongest is never strong enough to be always the master, unless he transforms strength into right, and obedience into duty.

PURPOSE CTR9 is a subunit of the PAF1 complex (PAF1C) that plays a crucial role in transcription regulation by binding CTR9 to RNA polymerase II. It is involved in transcription-coupled histone modification through promoting H3K4 and H3K36 methylation. We describe the clinical and molecular studies in 13 probands, harboring likely pathogenic CTR9 missense variants, collected through GeneMatcher. METHODS Exome sequencing was performed in all individuals. CTR9 variants were assessed through 3-dimensional modeling of the activated human transcription complex Pol II-DSIF-PAF-SPT6 and the PAF1/CTR9 complex. H3K4/H3K36 methylation analysis, mitophagy assessment based on tetramethylrhodamine ethyl ester perchlorate immunofluorescence, and RNA-sequencing in skin fibroblasts from 4 patients was performed. RESULTS Common clinical findings were variable degrees of intellectual disability, hypotonia, joint hyperlaxity, speech delay, coordination problems, tremor, and autism spectrum disorder. Mild dysmorphism and cardiac anomalies were less frequent. For 11 CTR9 variants, de novo occurrence was shown. Three-dimensional modeling predicted a likely disruptive effect of the variants on local CTR9 structure and protein interaction. Additional studies in fibroblasts did not unveil the downstream functional consequences of the identified variants. CONCLUSION We describe a neurodevelopmental disorder caused by (mainly) de novo variants in CTR9, likely affecting PAF1C function.

Neddylation has been implicated in various cellular pathways and in the pathophysiology of numerous diseases. We identified four individuals with bi-allelic variants in NAE1, which encodes the neddylation E1 enzyme. Pathogenicity was supported by decreased NAE1 abundance and overlapping clinical and cellular phenotypes. To delineate how cellular consequences of NAE1 deficiency would lead to the clinical phenotype, we focused primarily on the rarest phenotypic features, based on the assumption that these would best reflect the pathophysiology at stake. Two of the rarest features, neuronal loss and lymphopenia worsening during infections, suggest that NAE1 is required during cellular stress caused by infections to protect against cell death. In support, we found that stressing the proteasome system with MG132-requiring upregulation of neddylation to restore proteasomal function and proteasomal stress-led to increased cell death in fibroblasts of individuals with NAE1 genetic variants. Additionally, we found decreased lymphocyte counts after CD3/CD28 stimulation and decreased NF-κB translocation in individuals with NAE1 variants. The rarest phenotypic feature-delayed closure of the ischiopubic rami-correlated with significant downregulation of RUN2X and SOX9 expression in transcriptomic data of fibroblasts. Both genes are involved in the pathophysiology of ischiopubic hypoplasia. Thus, we show that NAE1 plays a major role in (skeletal) development and cellular homeostasis during stress. Our approach suggests that a focus on rare phenotypic features is able to provide significant pathophysiological insights in diseases caused by mutations in genes with pleiotropic effects.

Congenital myasthenic syndrome (CMS) is a heterogeneous condition associated with 34 different genes, including SLC5A7, which encodes the high-affinity choline transporter 1 (CHT1). CHT1 is expressed in presynaptic neurons of the neuromuscular junction where it uses the inward sodium gradient to reuptake choline. Biallelic CHT1 mutations often lead to neonatal lethality, and less commonly to non-lethal motor weakness and developmental delays. Here, we report detailed biochemical characterization of two novel mutations in CHT1, p.I294T and p.D349N, which we identified in an 11-year-old patient with a history of neonatal respiratory distress, and subsequent hypotonia and global developmental delay. Heterologous expression of each CHT1 mutant in human embryonic kidney cells showed two different mechanisms of reduced protein function. The p.I294T CHT1 mutant transporter function was detectable, but its abundance and half-life were significantly reduced. In contrast, the p.D349N CHT1 mutant was abundantly expressed at the cell membrane, but transporter function was absent. The residual function of the p.I294T CHT1 mutant may explain the non-lethal form of CMS in this patient, and the divergent mechanisms of reduced CHT1 function that we identified may guide future functional studies of the CHT1 myasthenic syndrome. Based on these in vitro studies that provided a diagnosis, treatment with cholinesterase inhibitor together with physical and occupational therapy significantly improved the patient’s strength and quality of life.

The study aimed at widening the clinical and genetic spectrum of ASXL3-related syndrome, a neurodevelopmental disorder, caused by truncating variants in the ASXL3 gene. In this international collaborative study, we have undertaken a detailed clinical and molecular analysis of 45 previously unpublished individuals with ASXL3-related syndrome, as well as a review of all previously published individuals. We have reviewed the rather limited functional characterization of pathogenic variants in ASXL3 and discuss current understanding of the consequences of the different ASXL3 variants. In this comprehensive analysis of ASXL3-related syndrome, we define its natural history and clinical evolution occurring with age. We report familial ASXL3 pathogenic variants, characterize the phenotype in mildly affected individuals and discuss nonpenetrance. We also discuss the role of missense variants in ASXL3. We delineate a variable but consistent phenotype. The most characteristic features are neurodevelopmental delay with consistently limited speech, significant neuro-behavioral issues, hypotonia, and feeding difficulties. Distinctive features include downslanting palpebral fissures, hypertelorism, tubular nose with a prominent nasal bridge, and low-hanging columella. The presented data will inform clinical management of individuals with ASXL3-related syndrome and improve interpretation of new ASXL3 sequence variants.

Purpose To expand the recent description of a new neurodevelopmental syndrome related to alterations in CDK19. Methods Individuals were identified through international collaboration. Functional studies included autophosphorylation assays for CDK19 Gly28Arg and Tyr32His variants and in vivo zebrafish assays of the CDK19(G28R) and CDK19(Y32H). Results We describe 11 unrelated individuals (age range: 9 months to 14 years) with de novo missense variants mapped to the kinase domain of CDK19, including two recurrent changes at residues Tyr32 and Gly28. In vitro autophosphorylation and substrate phosphorylation assays revealed that kinase activity of protein was lower for p.Gly28Arg and higher for p.Tyr32His substitutions compared with that of the wild-type protein. Injection of CDK19 messenger RNA (mRNA) with either the Tyr32His or the Gly28Arg variants using in vivo zebrafish model significantly increased fraction of embryos with morphological abnormalities. Overall, the phenotype of the now 14 individuals with CDK19-related disorder includes universal developmental delay and facial dysmorphism, hypotonia (79%), seizures (64%), ophthalmologic anomalies (64%), and autism/autistic traits (56%). Conclusion CDK19 de novo missense variants are responsible for a novel neurodevelopmental disorder. Both kinase assay and zebrafish experiments showed that the pathogenetic mechanism may be more diverse than previously thought.

THG1L-associated autosomal recessive ataxia belongs to a group of disorders that occur due to abnormal mitochondrial tRNA modification. The product of THG1L is the tRNA-histidine guanylyltransferase 1-like enzyme that catalyzes the 3'-5"addition of guanine to the 5"-end of tRNA-histidine in the mitochondrion. To date, five individuals with homozygosity for p.(Val55Ala) in THG1L have been reported and presented with mild delays or normal development and cerebellar dysfunction. We present seven individuals with biallelic variants in THG1L. Three individuals were compound heterozygous for the p.(Cys51Trp) and p.(Val55Ala) variants and presented with profound developmental delays, microcephaly, intractable epilepsy, and cerebellar hypoplasia. Four siblings were homozygous for the p.(Val55Ala) variant and presented with cerebellar ataxia with cerebellar vermis hypoplasia, dysarthria, mild developmental delays, and normal/near-normal cognition. All seven patients were of Ashkenazi Jewish descent. Carrier rates for the two variants were calculated in a cohort of 26,731 Ashkenazi Jewish individuals tested by the Dor Yeshorim screening program. The p.(Cys51Trp) variant is novel and was found in 40 of the Ashkenazi Jewish individuals tested, with a carrier rate of 1 in 668 (0.15%). The p.(Val55Ala) variant was found in 229 of the Ashkenazi Jewish individuals tested, with a carrier rate of 1 in 117 (0.85%). The individuals with compound heterozygosity of the p.(Val55Ala) and p.(Cys51Trp) variants expand the phenotypic spectrum of THG1L-related disorders to include severe epileptic encephalopathy. The individuals with homozygosity of the p.(V55A) variant further establish the associated mild and slowly progressive or nonprogressive neurodevelopmental phenotype.

Nonsyndromic hearing loss is genetically heterogeneous. Despite comprehensive genetic testing, many cases remain unsolved because the clinical significance of identified variants is uncertain or because biallelic pathogenic variants are not identified for presumed autosomal recessive cases. Common synonymous variants are often disregarded. Determining the pathogenicity of synonymous variants may improve genetic diagnosis. We report a synonymous variant c.9861 C > T/p.(Gly3287=) in MYO15A in homozygosity or compound heterozygosity with another pathogenic or likely pathogenic MYO15A variant in 10 unrelated families with nonsyndromic sensorineural hearing loss. Biallelic variants in MYO15A were identified in 21 affected and were absent in 22 unaffected siblings. A mini-gene assay confirms that the synonymous variant leads to abnormal splicing. The variant is enriched in the Ashkenazi Jewish population. Individuals carrying biallelic variants involving c.9861 C > T often exhibit progressive post-lingual hearing loss distinct from the congenital profound deafness typically associated with biallelic loss-of-function MYO15A variants. This study establishes the pathogenicity of the c.9861 C > T variant in MYO15A and expands the phenotypic spectrum of MYO15A-related hearing loss. Our work also highlights the importance of multicenter collaboration and data sharing to establish the pathogenicity of a relatively common synonymous variant for improved diagnosis and management of hearing loss.

The SET domain containing 2, histone lysine methyltransferase encoded by SETD2 is a dual-function methyltransferase for histones and microtubules and plays an important role for transcriptional regulation, genomic stability, and cytoskeletal functions. Specifically, SETD2 is associated with trimethylation of histone H3 at lysine 36 (H3K36me3) and methylation of α-tubulin at lysine 40. Heterozygous loss of function and missense variants have previously been described with Luscan-Lumish syndrome (LLS), which is characterized by overgrowth, neurodevelopmental features, and absence of overt congenital anomalies. We have identified 15 individuals with de novo variants in codon 1740 of SETD2 whose features differ from those with LLS. Group 1 consists of 12 individuals with heterozygous variant c.5218C>T p.(Arg1740Trp) and Group 2 consists of 3 individuals with heterozygous variant c.5219G>A p.(Arg1740Gln). The phenotype of Group 1 includes microcephaly, profound intellectual disability, congenital anomalies affecting several organ systems, and similar facial features. Individuals in Group 2 had moderate to severe intellectual disability, low normal head circumference, and absence of additional major congenital anomalies. While LLS is likely due to loss of function of SETD2, the clinical features seen in individuals with variants affecting codon 1740 are more severe suggesting an alternative mechanism, such as gain of function, effects on epigenetic regulation, or posttranslational modification of the cytoskeleton. Our report is a prime example of different mutations in the same gene causing diverging phenotypes and the features observed in Group 1 suggest a new clinically recognizable syndrome uniquely associated with the heterozygous variant c.5218C>T p.(Arg1740Trp) in SETD2.

MORC2 encodes an ATPase that plays a role in chromatin remodeling, DNA repair, and transcriptional regulation. Heterozygous variants in MORC2 have been reported in individuals with autosomal-dominant Charcot-Marie-Tooth disease type 2Z and spinal muscular atrophy, and the onset of symptoms ranges from infancy to the second decade of life. Here, we present a cohort of 20 individuals referred for exome sequencing who harbor pathogenic variants in the ATPase module of MORC2. Individuals presented with a similar phenotype consisting of developmental delay, intellectual disability, growth retardation, microcephaly, and variable craniofacial dysmorphism. Weakness, hyporeflexia, and electrophysiologic abnormalities suggestive of neuropathy were frequently observed but were not the predominant feature. Five of 18 individuals for whom brain imaging was available had lesions reminiscent of those observed in Leigh syndrome, and five of six individuals who had dilated eye exams had retinal pigmentary abnormalities. Functional assays revealed that these MORC2 variants result in hyperactivation of epigenetic silencing by the HUSH complex, supporting their pathogenicity. The described set of morphological, growth, developmental, and neurological findings and medical concerns expands the spectrum of genetic disorders resulting from pathogenic variants in MORC2.

We report the case of a 39-year-old woman who presented with generalized malaise; lymphadenopathy; arthritis; dactylitis; ecchymosis; acute onycholysis; and a red, nonpruritic, nonscaly, mottled rash on the right breast 24 hours after the first injections of ixekizumab for psoriasis and psoriatic arthritis. Ixekizumab is a humanized IgG4 monoclonal antibody that binds to IL-17A. Adverse events of ixeki-zumab include infection, inflammatory bowel disease, candidiasis and tinea infections, severe injection-site reactions, arthralgia, headache, infections, neutropenia, and thrombocytopenia. Other biologics, specifically tumor necrosis factor (TNF) inhibitors, have been reported to cause onycholysis attributed to immune dysregulation. We propose that ixekizumab alters the inflammatory cascade that underlies the induction of acute onycholysis and arthritis.

We report the case of a 14 year old Yemenite female diagnosed with autosomal recessive skeletal dysplasia secondary to a novel mutation of CSGALNACT1. She was initially referred to pediatric endocrine for poor linear growth at the age of 11 year 7 months. At that time, her height was well below the growth curve with z-score of -3.51. She had no reported history of intellectual disability. She had a normal MRI of the brain as well as normal growth factors, growth hormone stimulation test, thyroid function, IgA celiac antibodies, and a normal karyotype (46,XX). SHOX and microarray were negative. Her bone age was slightly delayed at 10-11 years with a chronological age of 11y8m. On initial evaluation by genetics, she was normocephalic with no dysmorphic facial features. She had proportionate limbs but was noted to have mild lumbar lordosis, increased joint laxity, and flattened feet with fifth toe clinodactyly. Notably there was a family history of consanguinity (parents are first cousins once removed). A skeletal dysplasia gene panel was not thought to be indicated, and she was referred back to endocrine. She was lost to follow up with endocrine but returned to clinic after 1 year when she was post-menarchal. She continued to have poor linear growth. Upon reevaluation, she was noted to additionally have a high-arched palate and shortened hallux. A panel for skeletal dysplasia was sent which detected a novel homozygous mutation of CSGALNACT1 with autosomal recessive inheritance. CSGALNACT1 encodes chondroitin sulfate N-acetylgalactosaminyl transferase which is crucial for chondroitin sulfate chain biosynthesis and glycosaminoglycan synthesis. Congenital disorders of glycosylation are genetically inherited conditions due to abnormal glycan biosynthesis. Glycosaminoglycans (GAGs) are vital in normal development of cartilage and the brain. We performed a PubMed search and saw four reported cases of individuals with mutations of CSGALNACT1. Clinically these individuals had relative macrocephaly, rhizomelia, hyperlordosis, joint laxity, and mild neurodevelopmental delay. Reported radiographic findings of affected individuals include advanced bone ages, flattened acetabular roofs, and vertebral anomalies. Our patient in contrast did not have overt dysmorphic features on exam nor reported intellectual disability to prompt a more immediate workup for skeletal dysplasia. There have been only a handful of cases with CSGALNACT1 mutations and skeletal dysplasia. These individuals more typically have findings of dysmorphia on exam including macrocephaly, lordosis, and joint laxity. Our patient lacked these typical features that are more normally associated with skeletal dysplasia yet was revealed to have a novel mutation of CSGALNACT1. Based on her initial genetic evaluation, her clinical findings were subtle and did not indicate a workup for skeletal dysplasia. Her case however shows that even in the absence of dysmorphic features, skeletal dysplasia should be considered in individuals with severe short stature. Presentation: No date and time listed

We report 281 individuals carrying a pathogenic recurrent NF1 missense variant at p.Met1149, p.Arg1276, or p.Lys1423, representing three nontruncating NF1 hotspots in the University of Alabama at Birmingham (UAB) cohort, together identified in 1.8% of unrelated NF1 individuals. About 25% (95% confidence interval: 20.5-31.2%) of individuals heterozygous for a pathogenic NF1 p.Met1149, p.Arg1276, or p.Lys1423 missense variant had a Noonan-like phenotype, which is significantly more compared with the "classic" NF1-affected cohorts (all p < .0001). Furthermore, p.Arg1276 and p.Lys1423 pathogenic missense variants were associated with a high prevalence of cardiovascular abnormalities, including pulmonic stenosis (all p < .0001), while p.Arg1276 variants had a high prevalence of symptomatic spinal neurofibromas (p < .0001) compared with "classic" NF1-affected cohorts. However, p.Met1149-positive individuals had a mild phenotype, characterized mainly by pigmentary manifestations without externally visible plexiform neurofibromas, symptomatic spinal neurofibromas or symptomatic optic pathway gliomas. As up to 0.4% of unrelated individuals in the UAB cohort carries a p.Met1149 missense variant, this finding will contribute to more accurate stratification of a significant number of NF1 individuals. Although clinically relevant genotype-phenotype correlations are rare in NF1, each affecting only a small percentage of individuals, together they impact counseling and management of a significant number of the NF1 population.

Many neuropsychiatric risk genes contribute to epigenetic regulation but little is known about specific chromatin-associated mechanisms governing the formation of neuronal connectivity. Here we show that transcallosal connectivity is critically dependent on C11orf46, a nuclear protein encoded in the chromosome 11p13 WAGR risk locus. C11orf46 haploinsufficiency was associated with hypoplasia of the corpus callosum. C11orf46 knockdown disrupted transcallosal projections and was rescued by wild type C11orf46 but not the C11orf46R236H mutant associated with intellectual disability. Multiple genes encoding key regulators of axonal development, including Sema6a, were hyperexpressed in C11orf46-knockdown neurons. RNA-guided epigenetic editing of Sema6a gene promoters via a dCas9-SunTag system with C11orf46 binding normalized SEMA6A expression and rescued transcallosal dysconnectivity via repressive chromatin remodeling by the SETDB1 repressor complex. Our study demonstrates that interhemispheric communication is sensitive to locus-specific remodeling of neuronal chromatin, revealing the therapeutic potential for shaping the brain’s connectome via gene-targeted designer activators and repressor proteins., Although many neuropsychiatric risk genes are known to contribute to epigenetic regulation of gene expression, very little is known about specific chromatin-associated mechanisms that govern the formation and maintenance of neuronal connectivity. Here, the authors report that transcallosal connectivity is critically dependent on C11orf46/ARL14EP, a nuclear protein encoded in the chromosome 11p13 WAGR risk locus, and that RNA-guided epigenetic editing of hyperexpressed Sema6a gene promoters in C11orf46-knockdown neurons resulted in normalization of expression and rescue of transcallosal dysconnectivity via repressive chromatin remodeling.

International audience; Histone Gene Cluster 1 Member E, HIST1H1E, encodes Histone H1.4, is one of a family of epigenetic regulator genes, acts as a linker histone protein, and is responsible for higher order chromatin structure. HIST1H1E syndrome (also known as Rahman syndrome, OMIM #617537) is a recently described intellectual disability (ID) syndrome. Since the initial description of five unrelated individuals with three different heterozygous protein-truncating variants (PTVs) in the HIST1H1E gene in 2017, we have recruited 30 patients, all with HIST1H1E PTVs that result in the same shift in frame and that cluster to a 94-base pair region in the HIST1H1E carboxy terminal domain. The identification of 30 patients with HIST1H1E variants has allowed the clarification of the HIST1H1E syndrome phenotype. Major findings include an ID and a recognizable facial appearance. ID was reported in all patients and is most frequently of moderate severity. The facial gestalt consists of a high frontal hairline and full lower cheeks in early childhood and, in later childhood and adulthood, affected individuals have a strikingly high frontal hairline, frontal bossing, and deep-set eyes. Other associated clinical features include hypothyroidism, abnormal dentition, behavioral issues, cryptorchidism, skeletal anomalies, and cardiac anomalies. Brain magnetic resonance imaging (MRI) is frequently abnormal with a slender corpus callosum a frequent finding.

Warsaw breakage syndrome (WABS), caused by bi-allelic variants in the DDX11 gene, is a rare cohesinopathy characterized by pre- and postnatal growth retardation, microcephaly, intellectual disability, facial dysmorphia, and sensorineural hearing loss due to cochlear hypoplasia. The DDX11 gene codes for an iron-sulfur DNA helicase in the Superfamily 2 helicases and plays an important role in genomic stability and maintenance. Fourteen individuals with WABS have been previously reported in the medical literature. Affected individuals have been of various ethnic backgrounds with different pathogenic variants. We report two unrelated individuals of Ashkenazi Jewish descent affected with WABS, who are homozygous for the c.1763-1G>C variant in the DDX11 gene. Their phenotype is consistent with previously reported individuals. RNA studies showed that this variant causes an alternative splice acceptor site leading to a frameshift in the open reading frame. Carrier screening of the c.1763-1G>C variant in the Jewish population revealed a high carrier frequency of 1 in 68 in the Ashkenazi Jewish population. Due to the high carrier frequency and the low number of affected individuals, we hypothesize a high rate of miscarriage of homozygous fetuses and/or subfertility for carrier couples. If the carrier frequency is reproducible in additional Ashkenazi Jewish populations, we suggest including DDX11 to Ashkenazi Jewish carrier screening panels.

Congenital diaphragmatic hernia (CDH) in neonates may occur as an isolated finding, in association with other anomalies, or as part of a genetic syndrome. We report the first case of an infant with CDH who presented with hyponatremic seizures due to adrenal hypoplasia congenita (AHC). The patient underwent repair of CDH defect. After an uncomplicated postoperative course while on discharge planning, he developed a seizure episode associated with severe hyponatremia and hyperkalemia. Extensive diagnostic workup revealed an NR0B1 gene variant confirming the diagnosis of X-linked AHC. The patient was eventually discharged home on hydrocortisone, fludrocortisone, and salt supplements. There are a few case reports of adrenal insufficiency in neonates with CDH, manifesting with symptoms before and immediately after reparative surgery. Clinical presentation of our patient was unique in manifesting as neonatal seizure secondary to severe hyponatremia after a stable postoperative phase. The patient’s electrolytes and hemodynamic status remained stable before, during, and after surgery for CDH. This case underlines the importance of taking detailed family history and continued vigilance for signs and symptoms of adrenal insufficiency in infants with repaired CDH by pediatricians and intensivists.

Introduction: M1231 is a first-in-class bispecific antibody drug conjugate (ADC) targeting mucin-1 (MUC1) and epidermal growth factor receptor (EGFR), that is conjugated with a novel hemiasterlin-related microtubule inhibitor payload. Following dose, M1231 binds to EGFR and co-binds to tumor-associated hypoglycosylated MUC1, internalizes into the tumor cell and traffics to lysosomes where the payload is enzymatically released to affect cell viability. Methods: A Multi-scale Systems Pharmacology model was developed to account for the ADC’s disposition and interactions with the underlying physiologic system, resulting in intracellular payload release in tumor cells to drive tumor growth inhibition (TGI). An in vitro model quantified ADC internalization and lysosomal trafficking in the MUC1 and EGFR-expressing cancer cell lines MDA-MB-468 and OVCAR-3. TGI was assessed in mice bearing MUC1-tumors from the squamous NSCLC patient-derived xenograft model, LUX003. Pharmacokinetics in cynomolgus monkeys was modeled using a Target Mediated Drug Disposition model and was allometrically scaled to humans. Data Summary: All preclinical modeling results were integrated and scaled to simulate plasma M1231 concentrations to predict the human dose and corresponding exposures. Tumor stasis was estimated to begin at a dose of 2.4 mg/kg every 3 weeks (Q3W) with a maximum tumor regression achieved at a dose of 4.3 mg/kg Q3W. Conclusions: The quantitative systems pharmacology model-based efficacious dose prediction range of 2.4 mg/kg to 4.3 mg/kg dosed Q3W informed the design of the ongoing M1231 first-in-human trial (NCT04695847). Citation Format: Anup Zutshi, Berend Neuteboom, Seema Kumar, Willem Sloot, Christine Knuehl, Julia Dotterweich, Jianguo Ma, Christiane Amendt, Karthik Venkatakrishnan, Taeshin Park, John Pappas, Kyoung-Ae Kim. Translational PK/PD/efficacy modeling and efficacious human dose prediction for a first-in-class MUC1-EGFR (M1231) bispecific antibody drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5423.

PPP3CA encodes the catalytic subunit of calcineurin, a calcium-calmodulin-regulated serine-threonine phosphatase. Loss-of-function (LoF) variants in the catalytic domain have been associated with epilepsy, while gain-of-function (GoF) variants in the auto-inhibitory domain cause multiple congenital abnormalities. We herein report five new patients with de novo PPP3CA variants. Interestingly, the two frameshift variants in this study and the six truncating variants reported previously are all located within a 26-amino acid region in the regulatory domain (RD). Patients with a truncating variant had more severe earlier onset seizures compared to patients with a LoF missense variant, while autism spectrum disorder was a more frequent feature in the latter. Expression studies of a truncating variant showed apparent RNA expression from the mutant allele, but no detectable mutant protein. Our data suggest that PPP3CA truncating variants clustered in the RD, causing more severe early-onset refractory epilepsy and representing a type of variants distinct from LoF or GoF missense variants.

ARGONAUTE-2 and associated miRNAs form the RNA-induced silencing complex (RISC), which targets mRNAs for translational silencing and degradation as part of the RNA interference pathway. Despite the essential nature of this process for cellular function, there is little information on the role of RISC components in human development and organ function. We identify 13 heterozygous mutations in AGO2 in 21 patients affected by disturbances in neurological development. Each of the identified single amino acid mutations result in impaired shRNA-mediated silencing. We observe either impaired RISC formation or increased binding of AGO2 to mRNA targets as mutation specific functional consequences. The latter is supported by decreased phosphorylation of a C-terminal serine cluster involved in mRNA target release, increased formation of dendritic P-bodies in neurons and global transcriptome alterations in patient-derived primary fibroblasts. Our data emphasize the importance of gene expression regulation through the dynamic AGO2-RNA association for human neuronal development., AGO2 binds to miRNAs to repress expression of cognate target mRNAs. Here the authors report that heterozygous AGO2 mutations result in defects in neurological development and impair RNA interference.

Background Over half of children with rare genetic diseases remain undiagnosed despite maximal clinical evaluation and DNA‐based genetic testing. As part of an Undiagnosed Diseases Program applying transcriptome (RNA) sequencing to identify the causes of these unsolved cases, we studied a child with severe infantile osteopetrosis leading to cranial nerve palsies, bone deformities, and bone marrow failure, for whom whole‐genome sequencing was nondiagnostic. Methods We performed transcriptome (RNA) sequencing of whole blood followed by analysis of aberrant transcript isoforms and osteoclast functional studies. Results We identified a pathogenic deep intronic variant in CLCN7 creating an unexpected, frameshifting pseudoexon causing complete loss of function. Functional studies, including osteoclastogenesis and bone resorption assays, confirmed normal osteoclast differentiation but loss of osteoclast function. Conclusion This is the first report of a pathogenic deep intronic variant in CLCN7, and our approach provides a model for systematic identification of noncoding variants causing osteopetrosis—a disease for which molecular‐genetic diagnosis can be pivotal for potentially curative hematopoietic stem cell transplantation. Our work illustrates that cryptic splice variants may elude DNA‐only sequencing and supports broad first‐line use of transcriptome sequencing for children with undiagnosed diseases., Over half of children with rare genetic diseases remain undiagnosed despite maximal DNA‐based genetic testing. Using transcriptome (RNA) sequencing, we identified a deep intronic variant in CLCN7 as the cause of a child's previously undiagnosed severe osteopetrosis syndrome. This work illustrates that cryptic splice variants may elude DNA‐only sequencing and supports first‐line use of transcriptome sequencing for undiagnosed diseases.

The GATA zing finger domain-containing protein 2B (GATAD2B) gene encodes the p66beta protein, a subunit of the MeCP1-Mi2/ nucleosome remodeling and deacetylase complex, which is involved in transcription regulation and chromatin remodeling. Pathogenic variants in the GATAD2B gene have recently been associated with a recognizable neurodevelopmental syndrome, characterized by intellectual disability, limited speech, childhood hypotonia, and dysmorphic features. The majority of reported patients resulted from de novo loss of function (LOF) variants. We report a patient identified through whole exome sequencing analysis where a healthy mother was found to be low level mosaic for the pathogenic LOF variant found in her child, who is affected with GATAD2B-associated neurodevelopmental disorder (GAND). This variant was only found with the use of next generation sequencing technology in the mother and confirmed by digital droplet PCR. We summarize additional patients with GATAD2B LOF variants from a literature review and with our patient we contribute to delineate the phenotypic spectrum of GAND. We highlight the importance of detailed genetic testing, testing method, and counseling for cases of somatic mosaicism in an unaffected parent of children with GAND. This inheritance may be underreported and has a direct impact on reproductive planning and prenatal diagnosis.

Acid sphingomyelinase deficiency (ASMD) is a rare lysosomal storage disorder with heterogeneous clinical manifestations, including hepatosplenomegaly and infiltrative pulmonary disease, and is associated with significant morbidity and mortality. Olipudase alfa (recombinant human acid sphingomyelinase) is an enzyme replacement therapy under development for the non-neurological manifestations of ASMD. We present a quantitative systems pharmacology (QSP) model supporting the clinical development of olipudase alfa. The model is multiscale and mechanistic, linking the enzymatic deficiency driving the disease to molecular-level, cellular-level, and organ-level effects. Model development was informed by natural history, and preclinical and clinical studies. By considering patient-specific pharmacokinetic (PK) profiles and indicators of disease severity, the model describes pharmacodynamic (PD) and clinical end points for individual patients. The ASMD QSP model provides a platform for quantitatively assessing systemic pharmacological effects in adult and pediatric patients, and explaining variability within and across these patient populations, thereby supporting the extrapolation of treatment response from adults to pediatrics.

Heterozygous variants in the arginine-glutamic acid dipeptide repeats gene (RERE) have been shown to cause neurodevelopmental disorder with or without anomalies of the brain, eye, or heart (NEDBEH). Here, we report nine individuals with NEDBEH who carry partial deletions or deleterious sequence variants in RERE. These variants were found to be de novo in all cases in which parental samples were available. An analysis of data from individuals with NEDBEH suggests that point mutations affecting the Atrophin-1 domain of RERE are associated with an increased risk of structural eye defects, congenital heart defects, renal anomalies, and sensorineural hearing loss when compared with loss-of-function variants that are likely to lead to haploinsufficiency. A high percentage of RERE pathogenic variants affect a histidine-rich region in the Atrophin-1 domain. We have also identified a recurrent two-amino-acid duplication in this region that is associated with the development of a CHARGE syndrome-like phenotype. We conclude that mutations affecting RERE result in a spectrum of clinical phenotypes. Genotype–phenotype correlations exist and can be used to guide medical decision making. Consideration should also be given to screening for RERE variants in individuals who fulfill diagnostic criteria for CHARGE syndrome but do not carry pathogenic variants in CHD7.

We describe unrelated individuals with ichthyosis, failure to thrive, thrombocytopenia, photophobia, and progressive hearing loss. Each have bi-allelic mutations in AP1B1, the gene encoding the β subunit of heterotetrameric adaptor protein 1 (AP-1) complexes, which mediate endomembrane polarization, sorting, and transport. In affected keratinocytes the AP-1 β subunit is lost, and the γ subunit is greatly reduced, demonstrating destabilization of the AP-1 complex. Affected cells and tissue contain an abundance of abnormal vesicles and show hyperproliferation, abnormal epidermal differentiation, and derangement of intercellular junction proteins. Transduction of affected cells with wild-type AP1B1 rescues the vesicular phenotype, conclusively establishing that loss of AP1B1 function causes this disorder.

Background While individual access to health records has traditionally been through paper and other physical media, there has been a recent push toward digitizing this process. Direct patient access to health data through application programming interfaces (APIs) is an important part of current United States policy initiatives, and Apple has created the product “Health Records on iPhone” to leverage APIs for this purpose. Objective The objective of this study was to examine the characteristics of patients at our institution who connected their personal iPhone devices to our electronic health records (EHRs) system through “Health Records on iPhone”, as compared to patients at our institution who used our patient portal but did not connect a personal device to our system. Methods We examined adult patients at our institution who had authorized an iPhone device to download their health data from the Partners HealthCare EHR via APIs through “Health Records on iPhone” from February 18, 2018 (the date this feature was enabled at our health system) until February 17, 2019. We compared these patients to adult patients who used our portal at least once during this period but did not authorize an iPhone device to download their data via APIs. Results Variables associated with an increased likelihood of using “Health Records on iPhone” included male gender (adjusted OR 3.36; 95% CI 3.11-3.62; P Conclusions Early results from the implementation of patient-facing APIs at a single institution suggest that there are opportunities for expanding these technologies to ensure all patients are aware of, and have access to, their health data on their personal devices. More work is needed on expanding these technologies to different patient populations.

Background: Sudden unexplained death in childhood (SUDC) is an understudied public health issue with multiple potential risk factors, including undiagnosed cardiac and seizure disorders, for which genetic risk factors can contribute. Methods: We studied whole exome sequence data from 124 consecutively ascertained trios (decedent child and unaffected parents) to test for excessive de novo mutations in cardiac, epilepsy and other genes. Findings: Among SUDC decedents, nonsynonymous mutations were enriched in genes associated with cardiac and seizure disorders relative to non-sudden death controls (odds ratio=9.76, p=2.15x10-4). Beyond these genes there was a trend for excess loss-of-function mutations in genes that are loss-of-function intolerant (odds ratio=2.34, p=0.08). In our cohort, two genes had recurrent missense mutations, RYR2 and CACNA1C. Both RYR2 mutations are known as pathogenic (p=1.7x10-7). Both CACNA1C mutations are within a short (104 nucleotide) exon (p=1.0x10-7). We found evidence for over-transmission of loss-of-function or pathogenic variants within cardiac and seizure disorder genes (11/14 transmitted, p=0.03). Interpretation: Eleven of 124 (8.9%) decedents carried likely pathogenic or pathogenic variants associated with sudden death via a lethal cardiac or seizure disorder. Of these, 7 were de novo in origin, 1 was a transmitted parental mosaic mutation, and 3 were transmitted from heterozygous parents. Funding Statement: This study was supported by funding from the SUDC Foundation and Finding A Cure for Epilepsy and Seizures (NYU). RWT was supported by NIH grants R01 DA040484 and R01 MH71739. MJA and DJT were supported by the Mayo Clinic Windland Smith Rice Comprehensive Sudden Cardiac Death Program. Declaration of Interests: MJA is a consultant for Audentes Therapeutics, Boston Scientific, Gilead Sciences, Invitae, Medtronic, Myokardia, and St. Jude Medical. MJA and Mayo Clinic have an equity/royalty relationship with AliveCor, Blue Ox Health, and StemoniX. However, none of these entities are related to study. DG reports he is cofounder and holds equity in Q State – Pairnomix and Praxis Therapeutics, and equity in Apostle Inc. He receives personal fees from AstraZeneca, outside the submitted work. RT reports his participation on the Scientific Advisory boards of Howard Hughes Medical Institute, the Institute of Neuroscience (Shanghai), and the Institute of Science and Technology (Vienna). RT also reports his participation in the Actelion Scientific Advisory Board (Basel) with no compensation during 3 year span. OD reports equity interest in Empatica and receive funding from NINDS on SUDEP research. MJA, OD and PL are members of the SUDC Foundation’s scientific advisory board. LGC is President of the SUDC Foundation. MJA, OD, PL and LGC do not participate in grant funding decisions or negotiations by the SUDC Foundation to NYU Langone Health. PL, DMH, RR, XW, JP have no declarations of interests. Ethics Approval Statement: Parental consent was obtained in this NYU Institutional Review Board approved study (# S14-01061).