The phenotypic and genotypic spectrum of individuals with mono- or biallelic ANK3 variants

ANK3 encodes ankyrin-G, a protein involved in neuronal development and signaling. Alternative splicing gives rise to three ankyrin-G isoforms comprising different domains with distinct expression patterns. Mono- or biallelic ANK3 variants are associated with non-specific syndromic intellectual disability in 14 individuals (seven with monoallelic and seven with biallelic variants). In this study, we describe the clinical features of 13 additional individuals and review the data on a total of 27 individuals (16 individuals with monoallelic and 11 with biallelic ANK3 variants) and demonstrate that the phenotype for biallelic variants is more severe. The phenotypic features include language delay (92%), autism spectrum disorder (76%), intellectual disability (78%), hypotonia (65%), motor delay (68%), attention deficit disorder (ADD) or attention deficit hyperactivity disorder (ADHD) (57%), sleep disturbances (50%), aggressivity/self-injury (37.5%), and epilepsy (35%). A notable phenotypic difference was presence of ataxia in three individuals with biallelic variants, but in none of the individuals with monoallelic variants. While the majority of the monoallelic variants are predicted to result in a truncated protein, biallelic variants are almost exclusively missense. Moreover, mono- and biallelic variants appear to be localized differently across the three different ankyrin-G isoforms, suggesting isoform-specific pathological mechanisms.</p

Prader-Willi and Angelman Syndromes: Mechanisms and Management

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are genetic imprinting disorders resulting from absent or reduced expression of paternal or maternal genes in chromosome 15q11q13 region, respectively. The most common etiology is deletion of the maternal or paternal 15q11q13 region. Methylation is the first line for molecular diagnostic testing; MS-MLPA is the most sensitive test. The molecular subtype of PWS/AS provides more accurate recurrence risk information for parents and for the individual affected with the condition. Management should include a multidisciplinary team by various medical subspecialists and therapists. Developmental and behavioral management of PWS and AS in infancy and early childhood includes early intervention services and individualized education programs for school-aged children. Here, we compare and discuss the mechanisms, pathophysiology, clinical features, and management of the two imprinting disorders, PWS and AS

Cornelia de Lange syndrome and molecular implications of the cohesin complex: Abstracts from the 7th biennial scientific and educational symposium 2016

Cornelia de Lange Syndrome (CdLS) is due to mutations in the genes for the structural and regulatory proteins that make up the cohesin complex, and is considered a cohesinopathy disorder or, more recently, a transcriptomopathy. New phenotypes have been recognized in this expanding field. There are multiple clinical issues facing individuals with all forms of CdLS, particularly in the neurodevelopmental system, but also gastrointestinal, cardiac, and musculoskeletal. Aspects of developmental and cell biology have found common endpoints in the biology of the cohesin complex, with improved understanding of the mechanisms, easier diagnostic tests, and the possibility of potential therapeutics, all major clinical implications for the individual with CdLS. The following abstracts are the presentations from the 7th Cornelia de Lange Syndrome Scientific and Educational Symposium, June 22-23, 2016, in Orlando, FL, in conjunction with the Cornelia de Lange Syndrome Foundation National Meeting. In addition to the scientific and clinical discussions, there were talks related to practical aspects of behavior including autism, transitions, communication, access to medical care, and databases. At the end of the symposium, a panel was held, which included several parents, affected individuals and genetic counselors, and discussed the greatest challenges in life and how this information can assist in guiding future research. The Research Committee of the CdLS Foundation organizes this meeting, reviews, and accepts abstracts, and subsequently disseminates the information to the families through members of the Clinical Advisory Board and publications. AMA CME credits were provided by Greater Baltimore Medical Center, Baltimore, M

A novel DPH5-related diphthamide-deficiency syndrome causing embryonic lethality or profound neurodevelopmental disorder

Purpose: Diphthamide is a post-translationally modified histidine essential for messenger RNA translation and ribosomal protein synthesis. We present evidence for DPH5 as a novel cause of embryonic lethality and profound neurodevelopmental delays (NDDs). Methods: Molecular testing was performed using exome or genome sequencing. A targeted Dph5 knockin mouse (C57BL/6Ncrl-Dph5(em1Mbp)/Mmucd) was created for a DPH5 p.His260Arg homozygous variant identified in 1 family. Adenosine diphosphate-ribosylation assays in DPH5-knockout human and yeast cells and in silico modeling were performed for the identified DPH5 potential pathogenic variants. Results: DPH5 variants p.His260Arg (homozygous), p.Asn110Ser and p.Arg207Ter (heterozygous), and p.Asn174LysfsTer10 (homozygous) were identified in 3 unrelated families with distinct overlapping craniofacial features, profound NDDs, multisystem abnormalities, and miscarriages. Dph5 p.His260Arg homozygous knockin was embryonically lethal with only 1 subviable mouse exhibiting impaired growth, craniofacial dysmorphology, and multisystem dysfunction recapitulating the human phenotype. Adenosine diphosphate-ribosylation assays showed absent to decreased function in DPH5-knockout human and yeast cells. In silico modeling of the variants showed altered DPH5 structure and disruption of its interaction with eEF2. Conclusion: We provide strong clinical, biochemical, and functional evidence for DPH5 as a novel cause of embryonic lethality or profound NDDs with multisystem involvement and expand diphthamide-deficiency syndromes and ribosomopathies. (C) 2022 Published by Elsevier Inc. on behalf of American College of Medical Genetics and Genomics

A novel DPH5-related diphthamide-deficiency syndrome causing embryonic lethality or profound neurodevelopmental disorder

PurposeDiphthamide is a post-translationally modified histidine essential for messenger RNA translation and ribosomal protein synthesis. We present evidence for DPH5 as a novel cause of embryonic lethality and profound neurodevelopmental delays (NDDs).MethodsMolecular testing was performed using exome or genome sequencing. A targeted Dph5 knockin mouse (C57BL/6Ncrl-Dph5em1Mbp/Mmucd) was created for a DPH5 p.His260Arg homozygous variant identified in 1 family. Adenosine diphosphate-ribosylation assays in DPH5-knockout human and yeast cells and in silico modeling were performed for the identified DPH5 potential pathogenic variants.ResultsDPH5 variants p.His260Arg (homozygous), p.Asn110Ser and p.Arg207Ter (heterozygous), and p.Asn174LysfsTer10 (homozygous) were identified in 3 unrelated families with distinct overlapping craniofacial features, profound NDDs, multisystem abnormalities, and miscarriages. Dph5 p.His260Arg homozygous knockin was embryonically lethal with only 1 subviable mouse exhibiting impaired growth, craniofacial dysmorphology, and multisystem dysfunction recapitulating the human phenotype. Adenosine diphosphate-ribosylation assays showed absent to decreased function in DPH5-knockout human and yeast cells. In silico modeling of the variants showed altered DPH5 structure and disruption of its interaction with eEF2.ConclusionWe provide strong clinical, biochemical, and functional evidence for DPH5 as a novel cause of embryonic lethality or profound NDDs with multisystem involvement and expand diphthamide-deficiency syndromes and ribosomopathies