Further delineation of the SCAF4-associated neurodevelopmental disorder.

While mostly de novo truncating variants in SCAF4 were recently identified in 18 individuals with variable neurodevelopmental phenotypes, knowledge on the molecular and clinical spectrum is still limited. We assembled data on 50 novel individuals with SCAF4 variants ascertained via GeneMatcher and personal communication. With detailed evaluation of clinical data, in silico predictions and structural modeling, we further characterized the molecular and clinical spectrum of the autosomal dominant SCAF4-associated neurodevelopmental disorder.

Comprehensive EHMT1 variants analysis broadens genotype-phenotype associations and molecular mechanisms in Kleefstra syndrome.

The shift to a genotype-first approach in genetic diagnostics has revolutionized our understanding of neurodevelopmental disorders, expanding both their molecular and phenotypic spectra. Kleefstra syndrome (KLEFS1) is caused by EHMT1 haploinsufficiency and exhibits broad clinical manifestations. EHMT1 encodes euchromatic histone methyltransferase-1-a pivotal component of the epigenetic machinery.

Vascular Ehlers-Danlos Syndrome: A Comprehensive Natural History Study in a Dutch National Cohort of 142 Patients.

Background: Vascular Ehlers-Danlos syndrome (vEDS) is a rare connective tissue disorder with a high risk for arterial, bowel, and uterine rupture, caused by heterozygous pathogenic variants in . The aim of this cohort study is to provide further insights into the natural history of vEDS and describe genotype-phenotype correlations in a Dutch multicenter cohort to optimize patient care and increase awareness of the disease.

Methods: Individuals with vEDS throughout the Netherlands were included.

Deep phenotyping of the neuroimaging and skeletal features in KBG syndrome: a study of 53 patients and review of the literature.

Background: KBG syndrome is caused by haploinsufficiency of and is characterised by macrodontia of upper central incisors, distinctive facial features, short stature, skeletal anomalies, developmental delay, brain malformations and seizures. The central nervous system (CNS) and skeletal features remain poorly defined.

Methods: CNS and/or skeletal imaging were collected from molecularly confirmed individuals with KBG syndrome through an international network.

Epilepsy is an important feature of KBG syndrome associated with poorer developmental outcome.

Objective: The aim of this study was to describe the epilepsy phenotype in a large international cohort of patients with KBG syndrome and to study a possible genotype-phenotype correlation.

Methods: We collected data on patients with ANKRD11 variants by contacting University Medical Centers in the Netherlands, an international network of collaborating clinicians, and study groups who previously published about KBG syndrome. All patients with a likely pathogenic or pathogenic ANKRD11 variant were included in our patient cohort and categorized into an "epilepsy group" or "non-epilepsy group".

GenIDA, a participatory patient registry for genetic forms of intellectual disability provides detailed caregiver-reported information on 237 individuals with Koolen-de Vries syndrome.

Purpose: GenIDA is an international patient registry for individuals diagnosed with intellectual disability, autism spectrum disorder, and/or epilepsy, which is based on an online questionnaire that is completed by parent caregivers. In this study, the GenIDA data on Koolen-de Vries syndrome (KdVS) was analyzed illustrating the value of GenIDA and patient/caregiver participation in rare genetic neurodevelopmental disorders (NDDs).

Methods: Recruitment was done on the GenIDA website from November 2016 to February 2022.

Missense variants in ANKRD11 cause KBG syndrome by impairment of stability or transcriptional activity of the encoded protein.

Purpose: Although haploinsufficiency of ANKRD11 is among the most common genetic causes of neurodevelopmental disorders, the role of rare ANKRD11 missense variation remains unclear. We characterized clinical, molecular, and functional spectra of ANKRD11 missense variants.

Methods: We collected clinical information of individuals with ANKRD11 missense variants and evaluated phenotypic fit to KBG syndrome.

Scrutinizing pathogenicity of the USH2A c.2276 G > T; p.(Cys759Phe) variant.

The USH2A variant c.2276 G > T (p.(Cys759Phe)) has been described by many authors as a frequent cause of autosomal recessive retinitis pigmentosa (arRP).

Inherited variants in CHD3 show variable expressivity in Snijders Blok-Campeau syndrome.

Purpose: Common diagnostic next-generation sequencing strategies are not optimized to identify inherited variants in genes associated with dominant neurodevelopmental disorders as causal when the transmitting parent is clinically unaffected, leaving a significant number of cases with neurodevelopmental disorders undiagnosed.

Methods: We characterized 21 families with inherited heterozygous missense or protein-truncating variants in CHD3, a gene in which de novo variants cause Snijders Blok-Campeau syndrome.

Results: Computational facial and Human Phenotype Ontology-based comparisons showed that the phenotype of probands with inherited CHD3 variants overlaps with the phenotype previously associated with de novo CHD3 variants, whereas heterozygote parents are mildly or not affected, suggesting variable expressivity.

Potential added value of combined DPYD/DPD genotyping and phenotyping to prevent severe toxicity in patients with a variant and decreased dihydropyrimidine dehydrogenase enzyme activity.

Objective: To investigate if dihydropyrimidine dehydrogenase phenotyping has added value when combined with genotyping in predicting fluoropyrimidine-related toxicity.

Methods: Retrospective cohort study in which treatment and toxicity data were collected of 228 patients genotyped for four variants and phenotyped using an peripheral blood mononuclear cell assay.

Results: Severe toxicity occurred in 25% of patients with a variant and normal dihydropyrimidine dehydrogenase activity, in 21% of patients without a variant and with decreased dihydropyrimidine dehydrogenase activity, and in 29% of patients without a variant and with normal dihydropyrimidine dehydrogenase activity (controls).

Expanding the phenotype of ASXL3-related syndrome: A comprehensive description of 45 unpublished individuals with inherited and de novo pathogenic variants in ASXL3.

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.

A MT-TL1 variant identified by whole exome sequencing in an individual with intellectual disability, epilepsy, and spastic tetraparesis.

The genetic etiology of intellectual disability remains elusive in almost half of all affected individuals. Within the Solve-RD consortium, systematic re-analysis of whole exome sequencing (WES) data from unresolved cases with (syndromic) intellectual disability (n = 1,472 probands) was performed. This re-analysis included variant calling of mitochondrial DNA (mtDNA) variants, although mtDNA is not specifically targeted in WES.

From man to fly - convergent evidence links FBXO25 to ADHD and comorbid psychiatric phenotypes.

Background: Mental disorders, including Attention-Deficit/Hyperactivity Disorder (ADHD), have a complex etiology, and identification of underlying genetic risk factors is challenging. This study used a multistep approach to identify and validate a novel risk gene for ADHD and psychiatric comorbidity.

Methods: In a single family, severely affected by ADHD and cooccurring disorders, we applied single nucleotide polymorphism (SNP)-array analysis to detect copy-number variations (CNVs) linked to disease.