Bi-allelic variants in INTS11 are associated with a complex neurological disorder.

The Integrator complex is a multi-subunit protein complex that regulates the processing of nascent RNAs transcribed by RNA polymerase II (RNAPII), including small nuclear RNAs, enhancer RNAs, telomeric RNAs, viral RNAs, and protein-coding mRNAs. Integrator subunit 11 (INTS11) is the catalytic subunit that cleaves nascent RNAs, but, to date, mutations in this subunit have not been linked to human disease. Here, we describe 15 individuals from 10 unrelated families with bi-allelic variants in INTS11 who present with global developmental and language delay, intellectual disability, impaired motor development, and brain atrophy. Consistent with human observations, we find that the fly ortholog of INTS11, dIntS11, is essential and expressed in the central nervous systems in a subset of neurons and most glia in larval and adult stages. Using Drosophila as a model, we investigated the effect of seven variants. We found that two (p.Arg17Leu and p.His414Tyr) fail to rescue the lethality of null mutants, indicating that they are strong loss-of-function variants. Furthermore, we found that five variants (p.Gly55Ser, p.Leu138Phe, p.Lys396Glu, p.Val517Met, and p.Ile553Glu) rescue lethality but cause a shortened lifespan and bang sensitivity and affect locomotor activity, indicating that they are partial loss-of-function variants. Altogether, our results provide compelling evidence that integrity of the Integrator RNA endonuclease is critical for brain development.

TRIM71 mutations cause a neurodevelopmental syndrome featuring ventriculomegaly and hydrocephalus.

Congenital hydrocephalus (CH), characterized by cerebral ventriculomegaly, is one of the most common reasons for pediatric brain surgery. Recent studies have implicated lin-41 (lineage variant 41)/TRIM71 (tripartite motif 71) as a candidate CH risk gene, however, TRIM71 variants have not been systematically examined in a large patient cohort or conclusively linked with an OMIM syndrome. Through cross-sectional analysis of the largest assembled cohort of patients with cerebral ventriculomegaly, including neurosurgically-treated CH (totaling 2,697 parent-proband trios and 8,091 total exomes), we identified 13 protein-altering de novo variants (DNVs) in TRIM71 in unrelated children exhibiting variable ventriculomegaly, CH, developmental delay, dysmorphic features, and other structural brain defects including corpus callosum dysgenesis and white matter hypoplasia. Eight unrelated patients were found to harbor arginine variants, including two recurrent missense DNVs, at homologous positions in RPXGV motifs of different NHL domains. Seven additional patients with rare, damaging, unphased or transmitted variants of uncertain significance were also identified. NHL-domain variants of TRIM71 exhibited impaired binding to the canonical TRIM71 target CDKN1A; other variants failed to direct the subcellular localization of TRIM71 to processing bodies. Single-cell transcriptomic analysis of human embryos revealed expression of TRIM71 in early first-trimester neural stem cells of the brain. These data show TRIM71 is essential for human brain morphogenesis and that TRIM71 mutations cause a novel neurodevelopmental syndrome featuring ventriculomegaly and CH.

Delineation of a Human Mendelian Disorder of the DNA Demethylation Machinery: TET3 Deficiency.

Germline pathogenic variants in chromatin-modifying enzymes are a common cause of pediatric developmental disorders. These enzymes catalyze reactions that regulate epigenetic inheritance via histone post-translational modifications and DNA methylation. Cytosine methylation (5-methylcytosine [5mC]) of DNA is the quintessential epigenetic mark, yet no human Mendelian disorder of DNA demethylation has yet been delineated. Here, we describe in detail a Mendelian disorder caused by the disruption of DNA demethylation. TET3 is a methylcytosine dioxygenase that initiates DNA demethylation during early zygote formation, embryogenesis, and neuronal differentiation and is intolerant to haploinsufficiency in mice and humans. We identify and characterize 11 cases of human TET3 deficiency in eight families with the common phenotypic features of intellectual disability and/or global developmental delay; hypotonia; autistic traits; movement disorders; growth abnormalities; and facial dysmorphism. Mono-allelic frameshift and nonsense variants in TET3 occur throughout the coding region. Mono-allelic and bi-allelic missense variants localize to conserved residues; all but one such variant occur within the catalytic domain, and most display hypomorphic function in an assay of catalytic activity. TET3 deficiency and other Mendelian disorders of the epigenetic machinery show substantial phenotypic overlap, including features of intellectual disability and abnormal growth, underscoring shared disease mechanisms.

The natural history of OTOF-related auditory neuropathy spectrum disorders: a multicenter study.

Pathogenic variations in the OTOF gene are a common cause of hearing loss. To refine the natural history and genotype-phenotype correlations of OTOF-related auditory neuropathy spectrum disorders (ANSD), audiograms and distortion product otoacoustic emissions (DPOAEs) were collected from a diverse cohort of individuals diagnosed with OTOF-related ANSD by comprehensive genetic testing and also reported in the literature. Comparative analysis was undertaken to define genotype-phenotype relationships using a Monte Carlo algorithm. 67 audiograms and 25 DPOAEs from 49 unique individuals positive for OTOF-related ANSD were collected. 51 unique OTOF pathogenic variants were identified of which 21 were missense and 30 were loss of function (LoF; nonsense, splice-site, copy number variants, and indels). There was a statistically significant difference in low, middle, and high frequency hearing thresholds between missense/missense and LoF/missense genotypes as compared to LoF/LoF genotypes (average hearing threshold for low, middle and high frequencies 70.9, 76.0, and 73.4 dB vs 88.5, 95.6, and 94.7 dB) via Tukey's test with age as a co-variate (P = 0.0180, 0.0327, and 0.0347, respectively). Hearing declined during adolescence with missense/missense and LoF/missense genotypes, with an annual mid-frequency threshold deterioration of 0.87 dB/year and 1.87 dB/year, respectively. 8.5% of frequencies measured via DPOAE were lost per year in individuals with serial tests. Audioprofiling of OTOF-related ANSD suggests significantly worse hearing with LoF/LoF genotypes. The unique pattern of variably progressive OTOF-related autosomal recessive ANSD may be amenable to gene therapy in selected clinical scenarios.

De Novo Heterozygous POLR2A Variants Cause a Neurodevelopmental Syndrome with Profound Infantile-Onset Hypotonia.

The RNA polymerase II complex (pol II) is responsible for transcription of all ∼21,000 human protein-encoding genes. Here, we describe sixteen individuals harboring de novo heterozygous variants in POLR2A, encoding RPB1, the largest subunit of pol II. An iterative approach combining structural evaluation and mass spectrometry analyses, the use of S. cerevisiae as a model system, and the assessment of cell viability in HeLa cells allowed us to classify eleven variants as probably disease-causing and four variants as possibly disease-causing. The significance of one variant remains unresolved. By quantification of phenotypic severity, we could distinguish mild and severe phenotypic consequences of the disease-causing variants. Missense variants expected to exert only mild structural effects led to a malfunctioning pol II enzyme, thereby inducing a dominant-negative effect on gene transcription. Intriguingly, individuals carrying these variants presented with a severe phenotype dominated by profound infantile-onset hypotonia and developmental delay. Conversely, individuals carrying variants expected to result in complete loss of function, thus reduced levels of functional pol II from the normal allele, exhibited the mildest phenotypes. We conclude that subtle variants that are central in functionally important domains of POLR2A cause a neurodevelopmental syndrome characterized by profound infantile-onset hypotonia and developmental delay through a dominant-negative effect on pol-II-mediated transcription of DNA.

The ubiquitin ligase UBE3B, disrupted in intellectual disability and absent speech, regulates metabolic pathways by targeting BCKDK.

Kaufman oculocerebrofacial syndrome (KOS) is a recessive neurodevelopmental disorder characterized by intellectual disability and lack of speech. KOS is caused by inactivating mutations in UBE3B, but the underlying biological mechanisms are completely unknown. We found that loss of Ube3b in mice resulted in growth retardation, decreased grip strength, and loss of vocalization. The brains of Ube3b-/- mice had hypoplasia of the corpus callosum, enlarged ventricles, and decreased thickness of the somatosensory cortex. Ube3b-/- cortical neurons had abnormal dendritic morphology and synapses. We identified 22 UBE3B interactors and found that branched-chain α-ketoacid dehydrogenase kinase (BCKDK) is an in vivo UBE3B substrate. Since BCKDK targets several metabolic pathways, we profiled plasma and cortical metabolomes from Ube3b-/- mice. Nucleotide metabolism and the tricarboxylic acid cycle were among the pathways perturbed. Substrate-induced mitochondrial respiration was reduced in skeletal muscle but not in liver of Ube3b-/- mice. To assess the relevance of these findings to humans, we identified three KOS patients who had compound heterozygous UBE3B mutations. We discovered changes in metabolites from similar pathways in plasma from these patients. Collectively, our results implicate a disease mechanism in KOS, suggest that it is a metabolic encephalomyopathy, and provide an entry to targeted therapies.

Missense Mutations of the Pro65 Residue of PCGF2 Cause a Recognizable Syndrome Associated with Craniofacial, Neurological, Cardiovascular, and Skeletal Features.

PCGF2 encodes the polycomb group ring finger 2 protein, a transcriptional repressor involved in cell proliferation, differentiation, and embryogenesis. PCGF2 is a component of the polycomb repressive complex 1 (PRC1), a multiprotein complex which controls gene silencing through histone modification and chromatin remodelling. We report the phenotypic characterization of 13 patients (11 unrelated individuals and a pair of monozygotic twins) with missense mutations in PCGF2. All the mutations affected the same highly conserved proline in PCGF2 and were de novo, excepting maternal mosaicism in one. The patients demonstrated a recognizable facial gestalt, intellectual disability, feeding problems, impaired growth, and a range of brain, cardiovascular, and skeletal abnormalities. Computer structural modeling suggests the substitutions alter an N-terminal loop of PCGF2 critical for histone biding. Mutant PCGF2 may have dominant-negative effects, sequestering PRC1 components into complexes that lack the ability to interact efficiently with histones. These findings demonstrate the important role of PCGF2 in human development and confirm that heterozygous substitutions of the Pro65 residue of PCGF2 cause a recognizable syndrome characterized by distinctive craniofacial, neurological, cardiovascular, and skeletal features.

De novo variants of NR4A2 are associated with neurodevelopmental disorder and epilepsy.

PURPOSE: This study characterizes the clinical and genetic features of nine unrelated patients with de novo variants in the NR4A2 gene. METHODS: Variants were identified and de novo origins were confirmed through trio exome sequencing in all but one patient. Targeted RNA sequencing was performed for one variant to confirm its splicing effect. Independent discoveries were shared through GeneMatcher. RESULTS: Missense and loss-of-function variants in NR4A2 were identified in patients from eight unrelated families. One patient carried a larger deletion including adjacent genes. The cases presented with developmental delay, hypotonia (six cases), and epilepsy (six cases). De novo status was confirmed for eight patients. One variant was demonstrated to affect splicing and result in expression of abnormal transcripts likely subject to nonsense-mediated decay. CONCLUSION: Our study underscores the importance of NR4A2 as a disease gene for neurodevelopmental disorders and epilepsy. The identified variants are likely causative of the seizures and additional developmental phenotypes in these patients.

Erythropoietin and Brain Magnetic Resonance Imaging Findings in Hypoxic-Ischemic Encephalopathy: Volume of Acute Brain Injury and 1-Year Neurodevelopmental Outcome.

In the Neonatal Erythropoietin and Therapeutic Hypothermia Outcomes study, 9/20 erythropoietin-treated vs 12/24 placebo-treated infants with hypoxic-ischemic encephalopathy had acute brain injury. Among infants with acute brain injury, the injury volume was lower in the erythropoietin than the placebo group (P = .004). Higher injury volume correlated with lower 12-month neurodevelopmental scores. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01913340.

A specific mutation in TBL1XR1 causes Pierpont syndrome.

BACKGROUND: The combination of developmental delay, facial characteristics, hearing loss and abnormal fat distribution in the distal limbs is known as Pierpont syndrome. The aim of the present study was to detect and study the cause of Pierpont syndrome. METHODS: We used whole-exome sequencing to analyse four unrelated individuals with Pierpont syndrome, and Sanger sequencing in two other unrelated affected individuals. Expression of mRNA of the wild-type candidate gene was analysed in human postmortem brain specimens, adipose tissue, muscle and liver. Expression of RNA in lymphocytes in patients and controls was additionally analysed. The variant protein was expressed in, and purified from, HEK293 cells to assess its effect on protein folding and function. RESULTS: We identified a single heterozygous missense variant, c.1337A>G (p.Tyr446Cys), in transducin ß-like 1 X-linked receptor 1 (TBL1XR1) as disease-causing in all patients. TBL1XR1 mRNA expression was demonstrated in pituitary, hypothalamus, white and brown adipose tissue, muscle and liver. mRNA expression is lower in lymphocytes of two patients compared with the four controls. The mutant TBL1XR1 protein assembled correctly into the nuclear receptor corepressor (NCoR)/ silencing mediator for retinoid and thyroid receptors (SMRT) complex, suggesting a dominant-negative mechanism. This contrasts with loss-of-function germline TBL1XR1 deletions and other TBL1XR1 mutations that have been implicated in autism. However, autism is not present in individuals with Pierpont syndrome. CONCLUSIONS: This study identifies a specific TBL1XR1 mutation as the cause of Pierpont syndrome. Deletions and other mutations in TBL1XR1 can cause autism. The marked differences between Pierpont patients with the p.Tyr446Cys mutation and individuals with other mutations and whole gene deletions indicate a specific, but as yet unknown, disease mechanism of the TBL1XR1 p.Tyr446Cys mutation.

Mutations in HIVEP2 are associated with developmental delay, intellectual disability, and dysmorphic features.

Human immunodeficiency virus type I enhancer binding protein 2 (HIVEP2) has been previously associated with intellectual disability and developmental delay in three patients. Here, we describe six patients with developmental delay, intellectual disability, and dysmorphic features with de novo likely gene-damaging variants in HIVEP2 identified by whole-exome sequencing (WES). HIVEP2 encodes a large transcription factor that regulates various neurodevelopmental pathways. Our findings provide further evidence that pathogenic variants in HIVEP2 lead to intellectual disabilities and developmental delay.

Correction: G. Bradley Schaefer. Clinical Genetic Aspects of ASD Spectrum Disorders. Int. J. Mol. Sci. 2016, 17, 180.

The author wishes to make a change to the published paper [1].[...].

Clinical Genetic Aspects of ASD Spectrum Disorders.

Early presumptions opined that autism spectrum disorder (ASD) was related to the rearing of these children by emotionally-distant mothers. Advances in the 1960s and 1970s clearly demonstrated the biologic basis of autism with a high heritability. Recent advances have demonstrated that specific etiologic factors in autism spectrum disorders can be identified in 30%-40% of cases. Based on early reports newer, emerging genomic technologies are likely to increase this diagnostic yield to over 50%. To date these investigations have focused on etiologic factors that are largely mono-factorial. The currently undiagnosed causes of ASDs will likely be found to have causes that are more complex. Epigenetic, multiple interacting loci, and four dimensional causes (with timing as a variable) are likely to be associated with the currently unidentifiable cases. Today, the "Why" is more important than ever. Understanding the causes of ASDs help inform families of important issues such as recurrence risk, prognosis, natural history, and predicting associated co-morbid medical conditions. In the current era of emerging efforts in "personalized medicine", identifying an etiology will be critical in identifying endo-phenotypic groups and individual variations that will allow for tailored treatment for persons with ASD.

Aplastic Anemia in Two Patients with Sex Chromosome Aneuploidies.

Sex chromosome aneuploidies range in incidence from rather common to exceedingly rare and have a variable phenotype. We report 2 patients with sex chromosome aneuploidies who developed severe aplastic anemia requiring treatment. The first patient had tetrasomy X (48,XXXX) and presented at 9 years of age, and the second patient had trisomy X (47,XXX) and presented at 5 years of age. Although aplastic anemia has been associated with other chromosomal abnormalities, sex chromosome abnormalities have not been traditionally considered a risk factor for this condition. A review of the literature reveals that at least one other patient with a sex chromosome aneuploidy (45,X) has suffered from aplastic anemia and that other autosomal chromosomal anomalies have been described. Despite the uncommon nature of each condition, it is possible that the apparent association is coincidental. A better understanding of the genetic causes of aplastic anemia remains important.

Phenotypic modifications of patients with full chromosome aneuploidies and concurrent suspected or confirmed second diagnoses.

The coexistence of two or more distinct genetic conditions is known to be a rare phenomenon. Full chromosome aneuploidies can be associated with a broad variety of cytogenetic abnormalities or single gene disorders resulting in phenotypic modifications that confuse the diagnostic process. We present six patients with primary aneuploidies and a suspected or confirmed secondary genetic diagnosis or unusual birth defect. Among the cases included, we report the first patients with concurrent Down syndrome in combination with Prader-Willi, Craniofacial Microsomia, and Stickler syndromes. We also describe only the second reported case of a neonate with Down syndrome and Marfan syndrome. In all cases, the unusual clinical presentations lead to further molecular cytogenetic studies as well as single or multi-gene molecular evaluations. We make emphasis on the importance of entertaining the possibility of coexistent diagnoses when the phenotype is not what is expected for aneuploidies rather than attributing the unusual findings to rare or unreported associations of the primary aneuploidy.

Myhre syndrome: Clinical features and restrictive cardiopulmonary complications.

Myhre syndrome, a connective tissue disorder characterized by deafness, restricted joint movement, compact body habitus, and distinctive craniofacial and skeletal features, is caused by heterozygous mutations in SMAD4. Cardiac manifestations reported to date have included patent ductus arteriosus, septal defects, aortic coarctation and pericarditis. We present five previously unreported patients with Myhre syndrome. Despite varied clinical phenotypes all had significant cardiac and/or pulmonary pathology and abnormal wound healing. Included herein is the first report of cardiac transplantation in patients with Myhre syndrome. A progressive and markedly abnormal fibroproliferative response to surgical intervention is a newly delineated complication that occurred in all patients and contributes to our understanding of the natural history of this disorder. We recommend routine cardiopulmonary surveillance for patients with Myhre syndrome. Surgical intervention should be approached with extreme caution and with as little invasion as possible as the propensity to develop fibrosis/scar tissue is dramatic and can cause significant morbidity and mortality.

Radioulnar Synostosis and Brain Abnormalities in a Patient With 17q21.31 Microdeletion Involving EFTUD2.

Mandibulofacial dysostosis with microcephaly is a rare syndromic craniofacial condition caused by heterozygous loss-of-function mutations of the EFTUD2 gene on 17q21.31. Thus far, the described musculoskeletal findings in patients with this condition include proximally placed or duplicated thumbs, overlapping toes, and toe syndactyly. We describe a severe case of a patient with a 17q21.31 microdeletion and many of the phenotypic features described in mandibulofacial dysostosis with microcephaly who had bilateral proximal radioulnar synostosis and brain abnormalities. This provides further evidence of the clinical overlap among mandibulofacial and acrofacial dysostoses syndromes and expands the phenotype of EFTUD2 haploinsufficiency due to larger deletions.

Adults' perceptions of genetic counseling and genetic testing.

PURPOSE: This study described the perceptions of genetic counseling and testing of adults (N = 116) attending a genetic education program. Understanding perceptions of genetic counseling, including the importance of counseling topics, will contribute to patient-focused care as clinical genetic applications for common, complex disorders evolve. METHODS: Participants completed a survey addressing: the importance of genetic counseling topics, benefits and negative effects of genetic testing, and sharing test results. RESULTS: Topics addressing practical information about genetic conditions were rated most important; topics involving conceptual genetic/genomic principles were rated least important. The most frequently identified benefit and negative effect of testing were prevention/early detection/treatment and psychological distress. Participants perceived that they were more likely to share test results with first-degree than other relatives. CONCLUSIONS: Findings suggest providing patients with practical information about genetic testing and genetic contributions to disease, while also determining whether their self-care abilities would be enhanced by teaching genetic/genomic principles.