Titel Deelnemers "Korte inhoud" "Identification of a DLG3 stop mutation in the MRX20 family" "Jolien Huyghebaert, Ligia Monica Mateiu, Ellen Elinck, Kirsten Van Rossem, Bregje Christiaenssen, Claudio D'Incal, Michael K. Mccormack, Alice Lazzarini, Geert Vandeweyer, Frank Kooy" "Here, we identified the causal mutation in the MRX20 family, one of the larger X-linked pedigrees that have been described in which no gene had been identified up till now. In 1995, the putative disease gene had been mapped to the pericentromeric region on the X chromosome, but no follow-up studies were performed. Here, whole exome sequencing (WES) on two affected and one unaffected family member revealed the c.195del/p.(Thr66ProfsTer55) mutation in the DLG3 gene (NM_021120.4) that segregated with the affected individuals in the family. DLG3 mutations have been consequently associated with intellectual disability and are a plausible explanation for the clinical abnormalities observed in this family. In addition, we identified two other variants co-segregating with the phenotype: a stop gain mutation in SSX1 (c.358G>T/p.(Glu120Ter)) (NM_001278691.2) and a nonsynonymous SNV in USP27X (c.56 A>G/p.(Gln19Arg)) (NM_001145073.3). RNA sequencing revealed 14 differentially expressed genes (p value < 0.1) in 7 affected males compared to 4 unaffected males of the family, including four genes known to be associated with neurological disorders. Thus, in this paper we identified the c.195del/p.(Thr66ProfsTer55) mutation in the DLG3 gene (NM_021120.4) as likely responsible for the phenotype observed in the MRX20 family." "Mouse models of fragile X-related disorders" "Rob Willemsen, Frank Kooy" "The fragile X-related disorders are an important group of hereditary disorders that are caused by expanded CGG repeats in the 5 ' untranslated region of the FMR1 gene or by mutations in the coding sequence of this gene. Two categories of pathological CGG repeats are associated with these disorders, full mutation alleles and shorter premutation alleles. Individuals with full mutation alleles develop fragile X syndrome, which causes autism and intellectual disability, whereas those with premutation alleles, which have shorter CGG expansions, can develop fragile X-associated tremor/ataxia syndrome, a progressive neurodegenerative disease. Thus, fragile X-related disorders can manifest as neurodegenerative or neurodevelopmental disorders, depending on the size of the repeat expansion. Here, we review mouse models of fragile X-related disorders and discuss how they have informed our understanding of neurodegenerative and neurodevelopmental disorders. We also assess the translational value of these models for developing rational targeted therapies for intellectual disability and autism disorders." "Unravelling the link between neurodevelopmental disorders and short tandem CGG-repeat expansions" "Dale Annear, Frank Kooy" "Neurodevelopmental disorders (NDDs) encompass a diverse group of disorders characterised by impaired cognitive abilities and developmental challenges. Short tandem repeats (STRs), repetitive DNA sequences found throughout the human genome, have emerged as potential contributors to NDDs. Specifically, the CGG trinucleotide repeat has been implicated in a wide range of NDDs, including Fragile X Syndrome (FXS), the most common inherited form of intellectual disability and autism. This review focuses on CGG STR expansions associated with NDDs and their impact on gene expression through repeat expansion-mediated epigenetic silencing. We explore the molecular mechanisms underlying CGG-repeat expansion and the resulting epigenetic modifications, such as DNA hypermethylation and gene silencing. Additionally, we discuss the involvement of other CGG STRs in neurodevelopmental diseases. Several examples, including FMR1, AFF2, AFF3, XYLT1, FRA10AC1, CBL, and DIP2B, highlight the complex relationship between CGG STR expansions and NDDs. Furthermore, recent advancements in this field are highlighted, shedding light on potential future research directions. Understanding the role of STRs, particularly CGG-repeats, in NDDs has the potential to uncover novel diagnostic and therapeutic strategies for these challenging disorders." "Insight and recommendations for fragile X-premutation-associated conditions from the Fifth International Conference on FMR1 Premutation" "Flora Tassone, Dragana Protic, Emily Graves Allen, Alison D. Archibald, Anna Baud, Ted W. Brown, Dejan B. Budimirovic, Jonathan Cohen, Brett Dufour, Rachel Eiges, Nicola Elvassore, Lidia V. Gabis, Samantha J. Grudzien, Deborah A. Hall, David Hessl, Abigail Hogan, Jessica Ezzell Hunter, Peng Jin, Poonnada Jiraanont, Jessica Klusek, Frank Kooy, Claudine M. Kraan, Cecilia Laterza, Andrea Lee, Karen Lipworth, Molly Losh, Danuta Loesch, Reymundo Lozano, Marsha R. Mailick, Apostolos Manolopoulos, Veronica Martinez-Cerdeno, Yingratana Mclennan, Robert M. Miller, Federica Alice Maria Montanaro, Matthew W. Mosconi, Sarah Nelson Potter, Melissa Raspa, Susan M. Rivera, Katharine Shelly, Peter K. Todd, Katarzyna Tutak, Jun Yi Wang, Anne Wheeler, Tri Indah Winarni, Marwa Zafarullah, Randi J. Hagerman" "The premutation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region and increased levels of FMR1 mRNA. Molecular mechanisms leading to fragile X-premutation-associated conditions (FXPAC) include cotranscriptional R-loop formations, FMR1 mRNA toxicity through both RNA gelation into nuclear foci and sequestration of various CGG-repeat-binding proteins, and the repeat-associated non-AUG (RAN)-initiated translation of potentially toxic proteins. Such molecular mechanisms contribute to subsequent consequences, including mitochondrial dysfunction and neuronal death. Clinically, premutation carriers may exhibit a wide range of symptoms and phenotypes. Any of the problems associated with the premutation can appropriately be called FXPAC. Fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND) can fall under FXPAC. Understanding the molecular and clinical aspects of the premutation of the FMR1 gene is crucial for the accurate diagnosis, genetic counseling, and appropriate management of affected individuals and families. This paper summarizes all the known problems associated with the premutation and documents the presentations and discussions that occurred at the International Premutation Conference, which took place in New Zealand in 2023." "Assortative mating and parental genetic relatedness contribute to the pathogenicity of variably expressive variants" "Corrine Smolen, Matthew Jensen, Lisa Dyer, Lucilla Pizzo, Anastasia Tyryshkina, Deepro Banerjee, Laura Rohan, Emily Huber, Laila El Khattabi, Paolo Prontera, Jean-Hubert Caberg, Anke Van Dijck, Charles Schwartz, Laurence Faivre, Patrick Callier, Anne-Laure Mosca-Boidron, Mathilde Lefebvre, Kate Pope, Penny Snell, Paul J. Lockhart, Lucia Castiglia, Ornella Galesi, Emanuela Avola, Teresa Mattina, Marco Fichera, Giuseppa Maria Luana Mandara, Maria Grazia Bruccheri, Olivier Pichon, Cedric Le Caignec, Radka Stoeva, Silvestre Cuinat, Sandra Mercier, Claire Beneteau, Sophie Blesson, Ashley Nordsletten, Dominique Martin-Coignard, Erik Sistermans, Frank Kooy, David J. Amor, Corrado Romano, Bertrand Isidor, Jane Juusola, Santhosh Girirajan" "We examined more than 97,000 families from four neurodevelopmental disease cohorts and the UK Biobank to identify phenotypic and genetic patterns in parents contributing to neurodevelopmental disease risk in children. We identified within- and cross-disorder correlations between six phenotypes in parents and children, such as obsessive-compulsive disorder (R = 0.32-0.38, p < 10(-126)). We also found that measures of sub-clinical autism features in parents are associated with several autism severity measures in children, including biparental mean Social Responsiveness Scale scores and proband Repetitive Behaviors Scale scores (regression coefficient = 0.14, p = 3.38 x 10(-4)). We further describe patterns of phenotypic similarity between spouses, where spouses show correlations for six neurological and psychiatric phenotypes, including a within-disorder correlation for depression (R = 0.24-0.68, p < 0.001) and a cross-disorder correlation between anxiety and bipolar disorder (R = 0.09-0.22, p < 10(-92)). Using a simulated population, we also found that assortative mating can lead to increases in disease liability over generations and the appearance of ""genetic anticipation"" in families carrying rare variants. We identified several families in a neurodevelopmental disease cohort where the proband inherited multiple rare variants in disease-associated genes from each of their affected parents. We further identified parental relatedness as a risk factor for neurodevelopmental disorders through its inverse relationship with variant pathogenicity and propose that parental relatedness modulates disease risk by increasing genome-wide homozygosity in children (R = 0.05-0.26, p < 0.05). Our results highlight the utility of assessing parent phenotypes and genotypes toward predicting features in children who carry rare variably expressive variants and implicate assortative mating as a risk factor for increased disease severity in these families." "ADNP in reverse gear" "Claudio D'Incal, Frank Kooy" "Chromatin remodeler Activity-Dependent Neuroprotective Protein (ADNP) contributes to syndromic autism" "Claudio D'Incal, Kirsten Van Rossem, Kevin De Man, Anthony Konings, Anke Van Dijck, Ludovico Rizzuti, Alessandro Vitriolo, Giuseppe Testa, Illana Gozes, Wim Vanden Berghe, Frank Kooy" "Background Individuals affected with autism often suffer additional co-morbidities such as intellectual disability. The genes contributing to autism cluster on a relatively limited number of cellular pathways, including chromatin remodeling. However, limited information is available on how mutations in single genes can result in such pleiotropic clinical features in affected individuals. In this review, we summarize available information on one of the most frequently mutated genes in syndromic autism the Activity-Dependent Neuroprotective Protein (ADNP). Results Heterozygous and predicted loss-of-function ADNP mutations in individuals inevitably result in the clinical presentation with the Helsmoortel–Van der Aa syndrome, a frequent form of syndromic autism. ADNP, a zinc finger DNA-binding protein has a role in chromatin remodeling: The protein is associated with the pericentromeric protein HP1, the SWI/SNF core complex protein BRG1, and other members of this chromatin remodeling complex and, in murine stem cells, with the chromodomain helicase CHD4 in a ChAHP complex. ADNP has recently been shown to possess R-loop processing activity. In addition, many additional functions, for instance, in association with cytoskeletal proteins have been linked to ADNP. Conclusions We here present an integrated evaluation of all current aspects of gene function and evaluate how abnormalities in chromatin remodeling might relate to the pleiotropic clinical presentation in individual“s” with Helsmoortel–Van der Aa syndrome." "Non-Mendelian inheritance patterns and extreme deviation rates of CGG repeats in autism" "Dale Annear, Geert Vandeweyer, Alba Sanchis-Juan, F. Lucy Raymond, Frank Kooy" "As expansions of CGG short tandem repeats (STRs) are established as the genetic etiology of many neurodevelopmental disorders, we aimed to elucidate the inheritance patterns and role of CGG STRs in autism-spectrum disorder (ASD). By genotyping 6063 CGG STR loci in a large cohort of trios and quads with an ASD-affected proband, we determined an unprecedented rate of CGG repeat length deviation across a single generation. Although the concept of repeat length being linked to deviation rate was solidified, we show how shorter STRs display greater degrees of size variation. We observed that CGG STRs did not segregate by Mendelian principles but with a bias against longer repeats, which appeared to magnify as repeat length increased. Through logistic regression, we identified 19 genes that displayed significantly higher rates and degrees of CGG STR expansion within the ASD-affected probands (P < 1 x 10(-5)). This study not only highlights novel repeat expansions that may play a role in ASD but also reinforces the hypothesis that CGG STRs are specifically linked to human cognition." "Vineland adaptive behavior scale in a cohort of four ADNP syndrome patients implicates age-dependent developmental delays with increased impact of activities of daily living" "Joseph Levine, Fahed Hakim, Frank Kooy, Illana Gozes" "Activity-dependent neuroprotective protein (ADNP) is one of the lead genes in autism spectrum disorder/intellectual disability. Heterozygous, de novo ADNP mutations cause the ADNP syndrome. Here, to evaluate natural history of the syndrome, mothers of two ADNP syndrome boys aged 6 and a half and two adults aged 27 years (man and woman) were subjected to Vineland III questionnaire assessing adaptive behavior. The boys were assessed again about 2 years after the first measurements. The skill measures, presented as standard scores (SS) included domains of communication, daily living, socialization, motor skills and a sum of adaptive behavior composite. The age equivalent (AE) and growth scale values (GSV) encompassing 11 subdomains assess the age level at which the subject's raw score is found at a norm sample median and the individual temporal progression, respectively. The norm referenced standard scores age-matched, mean 100 +/- 15 of the two children showed the lowest outcome in communication (SS: 20-30). Daily living skills presented SS of 50-60, with a possible potential loss of some activities as the child ages, especially in interpersonal relationships with people outside of the immediate family (boy A). In contrast, in socialization, both children were at the SS of 38, with some positive increase to SS of similar to 45 (interpersonal relations with family members and coping skills, depending on the particular individual), 2 years later. Interestingly, there was an apparent large difference in motor skills (gross and fine) at the young age, with subject B showing a relatively higher level of skills (SS: 70), decreasing to subject A level (SS: 40) 2 years later. Together, the adaptive behavior composite suggested a level of SS: 39-48 with B showing a potential increase (SS: 41-44) and A, a substantial decrease (SS: 48-39), suggesting a strong impact of daily living skills. Adults were at SS: 20, which is the lowest possible score. AE showed minor improvements for subject A and B, with all AE values being below 3 years. GSVs for subject A showed some improvement with age, especially in interpersonal, play and leisure, and gross motor subdomains. GSV for subject B showed minor improvements in the various subdomains. Notably, all subjects showed a percentile rank < 1 compared with age-matched norms except for subject B as to motor domain (2nd percentile) at the age of 6 years. In summary, the results, especially comparing SS and AEs between childhood and adulthood, implied a continuous deterioration of activities compared to the general population, encompassing a slower developmental process coupled to possible neurodegeneration, strongly supporting a great need for disease modifying medicinal procedures." "De novo mutations, genetic mosaicism and human disease" "Mohiuddin Mohiuddin, Frank Kooy, Christopher E. Pearson" "Mosaicism-the existence of genetically distinct populations of cells in a particular organism-is an important cause of genetic disease. Mosaicism can appear as de novo DNA mutations, epigenetic alterations of DNA, and chromosomal abnormalities. Neurodevelopmental or neuropsychiatric diseases, including autism-often arise by de novo mutations that usually not present in either of the parents. De novo mutations might occur as early as in the parental germline, during embryonic, fetal development, and/or post-natally, through ageing and life. Mutation timing could lead to mutation burden of less than heterozygosity to approaching homozygosity. Developmental timing of somatic mutation attainment will affect the mutation load and distribution throughout the body. In this review, we discuss the timing of de novo mutations, spanning from mutations in the germ lineage (all ages), to post-zygotic, embryonic, fetal, and post-natal events, through aging to death. These factors can determine the tissue specific distribution and load of de novo mutations, which can affect disease. The disease threshold burden of somatic de novo mutations of a particular gene in any tissue will be important to define."