De Novo Variants in WDR37 Are Associated with Epilepsy, Colobomas, Dysmorphism, Developmental Delay, Intellectual Disability, and Cerebellar Hypoplasia.

WD40 repeat-containing proteins form a large family of proteins present in all eukaryotes. Here, we identified five pediatric probands with de novo variants in WDR37, which encodes a member of the WD40 repeat protein family. Two probands shared one variant and the others have variants in nearby amino acids outside the WD40 repeats. The probands exhibited shared phenotypes of epilepsy, colobomas, facial dysmorphology reminiscent of CHARGE syndrome, developmental delay and intellectual disability, and cerebellar hypoplasia. The WDR37 protein is highly conserved in vertebrate and invertebrate model organisms and is currently not associated with a human disease. We generated a null allele of the single Drosophila ortholog to gain functional insights and replaced the coding region of the fly gene CG12333/wdr37 with GAL4. These flies are homozygous viable but display severe bang sensitivity, a phenotype associated with seizures in flies. Additionally, the mutant flies fall when climbing the walls of the vials, suggesting a defect in grip strength, and repeat the cycle of climbing and falling. Similar to wall clinging defect, mutant males often lose grip of the female abdomen during copulation. These phenotypes are rescued by using the GAL4 in the CG12333/wdr37 locus to drive the UAS-human reference WDR37 cDNA. The two variants found in three human subjects failed to rescue these phenotypes, suggesting that these alleles severely affect the function of this protein. Taken together, our data suggest that variants in WDR37 underlie a novel syndromic neurological disorder.

Redefining the Etiologic Landscape of Cerebellar Malformations.

Cerebellar malformations are diverse congenital anomalies frequently associated with developmental disability. Although genetic and prenatal non-genetic causes have been described, no systematic analysis has been performed. Here, we present a large-exome sequencing study of Dandy-Walker malformation (DWM) and cerebellar hypoplasia (CBLH). We performed exome sequencing in 282 individuals from 100 families with DWM or CBLH, and we established a molecular diagnosis in 36 of 100 families, with a significantly higher yield for CBLH (51%) than for DWM (16%). The 41 variants impact 27 neurodevelopmental-disorder-associated genes, thus demonstrating that CBLH and DWM are often features of monogenic neurodevelopmental disorders. Though only seven monogenic causes (19%) were identified in more than one individual, neuroimaging review of 131 additional individuals confirmed cerebellar abnormalities in 23 of 27 genetic disorders (85%). Prenatal risk factors were frequently found among individuals without a genetic diagnosis (30 of 64 individuals [47%]). Single-cell RNA sequencing of prenatal human cerebellar tissue revealed gene enrichment in neuronal and vascular cell types; this suggests that defective vasculogenesis may disrupt cerebellar development. Further, de novo gain-of-function variants in PDGFRB, a tyrosine kinase receptor essential for vascular progenitor signaling, were associated with CBLH, and this discovery links genetic and non-genetic etiologies. Our results suggest that genetic defects impact specific cerebellar cell types and implicate abnormal vascular development as a mechanism for cerebellar malformations. We also confirmed a major contribution for non-genetic prenatal factors in individuals with cerebellar abnormalities, substantially influencing diagnostic evaluation and counseling regarding recurrence risk and prognosis.

40th Annual David W Smith Workshop on Malformations and Morphogenesis: Abstracts of the 2019 Annual Meeting.

The 40th Annual David W. Smith Workshop on Malformations and Morphogenesis occurred August 23rd -28th, 2019 at the Snowbird Resort in Snowbird, Utah. The Workshop, which honors the legacy of David W. Smith, brought together clinicians and researchers interested in congenital malformations and their underlying mechanisms of morphogenesis from around the world. In addition to mechanisms of morphogenesis and delineation of new syndromes, the Workshop highlighted five themes: deformations, disruptions and fetal dysmorphology; orofacial clefting; central nervous system malformations; ciliopathies; and X-linked intellectual disabilities. This Conference Report includes the abstracts presented at the 2019 Workshop.

Further delineation of METTL23-associated intellectual disability.

METTL23 belongs to a family of methyltransferase like proteins (METTL) that transfer methyl group to various substrates. Recently, pathogenic homozygous variants in METTL23 were identified in patients from three families who presented with intellectual disability (ID) and variable dysmorphic features. In this report, we present unpublished phenotypic data from the original family as well as six new subjects from four families who also presented with mild to moderate ID and dysmorphic features, and were found to harbor four previously unpublished homozygous or compound heterozygous variants in METTL23. Our report further supports the role of this gene in autosomal recessive ID and emphasizes the mild but consistent facial features.

Kilquist syndrome: A novel syndromic hearing loss disorder caused by homozygous deletion of SLC12A2.

Syndromic sensorineural hearing loss is multigenic and associated with malformations of the ear and other organ systems. Herein we describe a child admitted to the NIH Undiagnosed Diseases Program with global developmental delay, sensorineural hearing loss, gastrointestinal abnormalities, and absent salivation. Next-generation sequencing revealed a uniparental isodisomy in chromosome 5, and a 22 kb homozygous deletion in SLC12A2, which encodes for sodium, potassium, and chloride transporter in the basolateral membrane of secretory epithelia. Functional studies using patient-derived fibroblasts showed truncated SLC12A2 transcripts and markedly reduced protein abundance when compared with control. Loss of Slc12a2 in mice has been shown to lead to deafness, abnormal neuronal growth and migration, severe gastrointestinal abnormalities, and absent salivation. Together with the described phenotype of the Slc12a2-knockout mouse model, our results suggest that the absence of functional SLC12A2 causes a new genetic syndrome and is crucial for the development of auditory, neurologic, and gastrointestinal tissues.

Rare SUZ12 variants commonly cause an overgrowth phenotype.

The Polycomb repressive complex 2 is an epigenetic writer and recruiter with a role in transcriptional silencing. Constitutional pathogenic variants in its component proteins have been found to cause two established overgrowth syndromes: Weaver syndrome (EZH2-related overgrowth) and Cohen-Gibson syndrome (EED-related overgrowth). Imagawa et al. (2017) initially reported a singleton female with a Weaver-like phenotype with a rare coding SUZ12 variant-the same group subsequently reported two additional affected patients. Here we describe a further 10 patients (from nine families) with rare heterozygous SUZ12 variants who present with a Weaver-like phenotype. We report four frameshift, two missense, one nonsense, and two splice site variants. The affected patients demonstrate variable pre- and postnatal overgrowth, dysmorphic features, musculoskeletal abnormalities and developmental delay/intellectual disability. Some patients have genitourinary and structural brain abnormalities, and there may be an association with respiratory issues. The addition of these 10 patients makes a compelling argument that rare pathogenic SUZ12 variants frequently cause overgrowth, physical abnormalities, and abnormal neurodevelopmental outcomes in the heterozygous state. Pathogenic SUZ12 variants may be de novo or inherited, and are sometimes inherited from a mildly-affected parent. Larger samples sizes will be needed to elucidate whether one or more clinically-recognizable syndromes emerge from different variant subtypes.

Mosaic Activating Mutations in FGFR1 Cause Encephalocraniocutaneous Lipomatosis.

Encephalocraniocutaneous lipomatosis (ECCL) is a sporadic condition characterized by ocular, cutaneous, and central nervous system anomalies. Key clinical features include a well-demarcated hairless fatty nevus on the scalp, benign ocular tumors, and central nervous system lipomas. Seizures, spasticity, and intellectual disability can be present, although affected individuals without seizures and with normal intellect have also been reported. Given the patchy and asymmetric nature of the malformations, ECCL has been hypothesized to be due to a post-zygotic, mosaic mutation. Despite phenotypic overlap with several other disorders associated with mutations in the RAS-MAPK and PI3K-AKT pathways, the molecular etiology of ECCL remains unknown. Using exome sequencing of DNA from multiple affected tissues from five unrelated individuals with ECCL, we identified two mosaic mutations, c.1638C>A (p.Asn546Lys) and c.1966A>G (p.Lys656Glu) within the tyrosine kinase domain of FGFR1, in two affected individuals each. These two residues are the most commonly mutated residues in FGFR1 in human cancers and are associated primarily with CNS tumors. Targeted resequencing of FGFR1 in multiple tissues from an independent cohort of individuals with ECCL identified one additional individual with a c.1638C>A (p.Asn546Lys) mutation in FGFR1. Functional studies of ECCL fibroblast cell lines show increased levels of phosphorylated FGFRs and phosphorylated FRS2, a direct substrate of FGFR1, as well as constitutive activation of RAS-MAPK signaling. In addition to identifying the molecular etiology of ECCL, our results support the emerging overlap between mosaic developmental disorders and tumorigenesis.

Population-Based Newborn Screening for Mucopolysaccharidosis Type II in Illinois: The First Year Experience.

OBJECTIVES: To assess the outcome of population-based newborn screening for mucopolysaccharidosis type II (MPS II) during the first year of screening in Illinois. STUDY DESIGN: Tandem mass spectrometry was used to measure iduronate-2-sulfatase (I2S) activity in dried blood spot specimens obtained from 162 000 infant samples sent to the Newborn Screening Laboratory of the Illinois Department of Public Health in Chicago. RESULTS: One case of MPS II and 14 infants with pseudodeficiency for I2S were identified. CONCLUSIONS: Newborn screening for MPS II by measurement of I2S enzyme activity was successfully integrated into the statewide newborn screening program in Illinois.

Solid tumor screening recommendations in trisomy 18.

The purpose of this study was to determine whether trisomy 18 patients are at an increased risk of tumor development and require formal tumor screening recommendations. A literature search of trisomy 18 patients with reports of tumors or malignancies, and compilation of all previously reported as well as new unreported cases was performed. 67 patients with trisomy 18 were found to have documented malignancies. 44 patients had hepatoblastomas, 21 patients had Wilms tumors, one patient had a functional neurogenic neoplasia, and one patient had Hodgkins lymphoma. The increasing numbers of reported malignancies in patients with trisomy 18 supports the indication for an early screening process. Specific screening recommendations are outlined consisting of imaging exams and laboratory values performed at specific intervals.

Retinoic acid receptor beta variant-related colonic hypoganglionosis.

Retinoic acid receptor beta (RARB) variants are heavily linked to pathologies of neural crest cell migration. The purpose of this report is to present a 23-month-old male with the previously described R387C RARB gain-of-function variant whose gastrointestinal issues and long-term constipation lead to the discovery of colonic hypoganglionosis. This case further delineates the pattern of malformation associated with RARB variants. The findings are also consistent with the known etiology of aganglionic colon due to failed neural crest cell migration.

Mutations Impairing GSK3-Mediated MAF Phosphorylation Cause Cataract, Deafness, Intellectual Disability, Seizures, and a Down Syndrome-like Facies.

Transcription factors operate in developmental processes to mediate inductive events and cell competence, and perturbation of their function or regulation can dramatically affect morphogenesis, organogenesis, and growth. We report that a narrow spectrum of amino-acid substitutions within the transactivation domain of the v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog (MAF), a leucine zipper-containing transcription factor of the AP1 superfamily, profoundly affect development. Seven different de novo missense mutations involving conserved residues of the four GSK3 phosphorylation motifs were identified in eight unrelated individuals. The distinctive clinical phenotype, for which we propose the eponym Aymé-Gripp syndrome, is not limited to lens and eye defects as previously reported for MAF/Maf loss of function but includes sensorineural deafness, intellectual disability, seizures, brachycephaly, distinctive flat facial appearance, skeletal anomalies, mammary gland hypoplasia, and reduced growth. Disease-causing mutations were demonstrated to impair proper MAF phosphorylation, ubiquitination and proteasomal degradation, perturbed gene expression in primary skin fibroblasts, and induced neurodevelopmental defects in an in vivo model. Our findings nosologically and clinically delineate a previously poorly understood recognizable multisystem disorder, provide evidence for MAF governing a wider range of developmental programs than previously appreciated, and describe a novel instance of protein dosage effect severely perturbing development.

De novo variants in Myelin regulatory factor (MYRF) as candidates of a new syndrome of cardiac and urogenital anomalies.

Myelin Regulatory Factor (MYRF) is a transcription factor that has previously been associated with the control of the expression of myelin-related genes. However, it is highly expressed in human tissues and mouse embryonic tissues outside the nervous system such as the stomach, lung, and small intestine. It has not previously been reported as a cause of any Mendelian disease. We report here two males with Scimitar syndrome [MIM 106700], and other features including penoscrotal hypospadias, cryptorchidism, pulmonary hypoplasia, tracheal anomalies, congenital diaphragmatic hernia, cleft spleen, thymic involution, and thyroid fibrosis. Gross neurologic functioning appears to be within normal limits. In both individuals a de novo variant in MYRF was identified using exome sequencing. Neither variant is found in gnomAD. Heterozygous variants in MYRF should be considered in patients with variants of Scimitar syndrome and urogenital anomalies.

Newborn Screening for Lysosomal Storage Disorders in Illinois: The Initial 15-Month Experience.

OBJECTIVES: To assess the outcomes of newborn screening for 5 lysosomal storage disorders (LSDs) in the first cohort of infants tested in the state of Illinois. STUDY DESIGN: Tandem mass spectrometry was used to assay for the 5 LSD-associated enzymes in dried blood spot specimens obtained from 219 973 newborn samples sent to the Newborn Screening Laboratory of the Illinois Department of Public Health in Chicago. RESULTS: The total number of cases with a positive diagnosis and the incidence for each disorder were as follows: Fabry disease, n = 26 (1 in 8454, including the p.A143T variant); Pompe disease, n = 10 (1 in 21 979); Gaucher disease, n = 5 (1 in 43 959); mucopolysaccharidosis (MPS) type 1, n = 1 (1 in 219 793); and Niemann-Pick disease type A/B, n = 2 (1 in 109 897). Twenty-two infants had a positive screen for 1 of the 5 disorders but could not be classified as either affected or unaffected after follow-up testing, including genotyping. Pseudodeficiencies for alpha-L-iduronidase and alpha-glucosidase were detected more often than true deficiencies. CONCLUSIONS: The incidences of Fabry disease and Pompe disease were significantly higher than published estimates, although most cases detected were predicted to be late onset. The incidences of Gaucher disease, MPS I, and Niemann-Pick disease were comparable with previously published estimates. A total of 16 infants could not be positively identified as either affected or unaffected. To validate the true risks and benefits of newborn screening for LSD, long term follow-up in these infants and those detected with later-onset disorders will be essential.

Procedures in the 1st year of life for children with trisomy 13 and trisomy 18, a 25-year, single-center review.

Care of the child born with trisomy 13 or 18 has evolved over the past few decades, leading to increased healthcare utilization. We hypothesized that there has been an increase in procedures across all intensity types, including major, invasive procedures. We performed a retrospective-cohort study of children with trisomy 13 or 18 from 1990 to 2014 in a quaternary, free-standing children's hospital. Children were identified using ICD-9 billing diagnoses. Procedures were identified during these encounters and categorized by intensity (major, intermediate, or minor). One hundred thirty-two children with trisomy 13 or 18 were identified. In children with trisomy 13, major procedures increased from period 1 (1990-1997) to period 3 (2006-2013) from 0.11 to 0.78 procedures per patient. For trisomy 18, the increase between the time periods was from 0.14 to 1.33 procedures per patient. By the end of the study period, nearly all trisomy 13 patients had a major procedure and the majority of those with trisomy 18 had undergone a major procedure. Estimated 1-year survival for those with a major procedure was 30% and 22% for trisomies 13 and 18, respectively. In conclusion, there was an increasing rate of procedures per patient of all intensity levels over the 25-year study period. Given differences in characteristics in those with trisomies 13 and 18, and effects of intervention on survival, an individualized approach to care of these patients should be employed by parents and healthcare providers, using factors such as trisomy type, infant gender, co-morbidities, and parental preference. © 2016 Wiley Periodicals, Inc.

Continuous Venovenous Hemodialysis Via Extracorporeal Membrane Oxygenation Pump for Treatment of Hyperammonemia Secondary to Propionic Acidemia in Monochorionic Diamniotic Twin Boys.

Late-preterm twins with propionic acidemia developed severe hyperammonemic encephalopathy at 5 days of age. Continuous venovenous hemodialysis was performed successfully for both infants via extracorporeal membrane oxygenation pump, and both rapidly improved. They were taken off continuous venovenous hemodialysis and extracorporeal membrane oxygenation and discharged with dietary therapy. At 3 years of age, neurodevelopment showed globally delayed milestones.

Braddock-Carey syndrome: A 21q22 contiguous gene syndrome encompassing RUNX1.

In 1994, Braddock and Carey first reported two unrelated girls with a new multiple malformation syndrome. The primary features included Pierre Robin sequence, persistent neonatal-onset thrombocytopenia, agenesis of the corpus callosum, a distinctive facies, enamel hypoplasia, and severe developmental delay. Since that time, there have been multiple other reported patients with a similar phenotype. In addition, several reports of thrombocytopenia and developmental delay have been documented in association with deletions in the Down syndrome critical region at 21q22. The similarity of the reported cases with deletions involving 21q22 with the clinical presentation of the two patients with Braddock-Carey syndrome resulted in a reinvestigation of the genetic etiology of these two patients 20 years after the original study. This investigation provides evidence that the etiology of this and other "Fanconi-like" disorders represent a newly recognized contiguous gene deletion syndrome involving 21q22 and specifically, the RUNX1 gene. © 2016 Wiley Periodicals, Inc.

Mutations in COQ4, an essential component of coenzyme Q biosynthesis, cause lethal neonatal mitochondrial encephalomyopathy.

BACKGROUND: The identification of the molecular basis of mitochondrial disorders continues to be challenging and expensive. The increasing usage of next-generation sequencing is facilitating the discovery of the genetic aetiology of heterogeneous phenotypes associated with these conditions. Coenzyme Q(10) (CoQ(10)) is an essential cofactor for mitochondrial respiratory chain complexes and other biochemical pathways. Mutations in genes involved in CoQ(10) biosynthesis cause primary CoQ(10) deficiency syndromes that can be treated with oral supplementation of ubiquinone. METHODS: We used whole exome sequencing to evaluate six probands from four unrelated families with clinical findings suggestive of a mitochondrial disorder. Clinical data were obtained by chart review, parental interviews, direct patient assessment and biochemical and pathological evaluation. RESULTS: We identified five recessive missense mutations in COQ4 segregating with disease in all four families. One mutation was found in a homozygous state in two unrelated Ashkenazi Jewish probands. All patients were female, and presented on the first day of life, and died in the neonatal period or early infancy. Clinical findings included hypotonia (6/6), encephalopathy with EEG abnormalities (4/4), neonatal seizures (3/6), cerebellar atrophy (4/5), cardiomyopathy (5/6) and lactic acidosis (4/6). Autopsy findings in two patients revealed neuron loss and reactive astrocytosis or cerebellar and brainstem hypoplasia and microdysgenesis. CONCLUSIONS: Mutations in COQ4 cause an autosomal recessive lethal neonatal mitochondrial encephalomyopathy associated with a founder mutation in the Ashkenazi Jewish population. The early mortality in our cohort suggests that COQ4 is an essential component of the multisubunit complex required for CoQ(10) biosynthesis.

35(th) Annual David W Smith Workshop on Malformations and Morphogenesis: abstracts of the 2014 annual meeting.

The 35(th) Annual David W Smith Workshop on Malformations and Morphogenesis was held on July 25-30, 2014 at the University of Wisconsin, Madison, Wisconsin. The conference, which honors the legacy of David Smith, brought together over 130 clinicians and researchers interested in congenital malformations and their underlying mechanisms of morphogenesis. As is the tradition of the meeting, the Workshop highlighted five themes besides mechanisms of morphogenesis: Evolution and Development, Minor Malformations, CHARGE syndrome, Craniofacial Development/ Malformations, and Disorders of Chromatin Remodeling. This Conference Report includes the abstracts presented at the Workshop.