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Abstract Background Say‐Barber‐Biesecker‐Young‐Simpson (SBBYSS) variant of Ohdo syndrome is a rare, autosomal dominant and clinically heterogenous disorder, caused by pathogenic variants in the KAT6B gene located on chromosome 10q22.2. KAT6B encodes a highly conserved histone acetyltransferase belonging to the MYST family. Currently, diseases caused by pathogenic variants in KAT6B (KAT6B‐related disorders) comprise two allelic entities: SBBYSS variant of Ohdo syndrome and genitopatellar syndrome (GPS). Increase in the number of cases with overlapping GPS/SBBYSS phenotype which makes it necessary to redefine this group of phenotypes as KAT6B‐related disorders or KAT6B spectrum disorders. Individuals with SBBYSS usually present with facial abnormalities, hypotonia, joint laxity, feeding problems, and long thumbs/great toes. This syndrome also typically involves skeletal problems including patellar hypoplasia/agenesis. Methods Here we report six SBBYS syndrome patients with the same dysmorphic features but a different course of the disease. One known and five novel KATB6 pathogenic variants were identified by molecular diagnostics using Next Generation Sequencing (NGS). Results We present a detailed phenotypic analysis of six individuals with KAT6B‐related disorders, in whom a heterozygous pathogenic variant in KAT6B gene was found. In all of our patients facial dysmorphism as well as developmental and speech delay were present. Additionally, all but one patients presented with hypotonia, ocular abnormalities and long thumbs. Most of our probands showed blepharophimosis and skeletal (mainly knee) defects. Contrary to previously reported severe patellar defects (hypoplasia/agenesis) anomalies presented by our patients were less severe (dysplasia, habitual dislocation, subluxation) referring to KAT6B‐related disorders. Conclusion While most of the anomalies found in our patients comply with SBBYSS criteria, phenotypic differences in our probands support a broader spectrum of the disease phenotype. To establish the range of this spectrum, a detailed analysis of clinical variability among patients with SBBYSS requires further investigation.

Background Joubert syndrome (JS) is a ciliopathy characterised by a distinctive brain malformation (the 'molar tooth sign'), developmental delay, abnormal eye movements and abnormal breathing pattern. Retinal dystrophy, cystic kidney disease, liver fibrosis and polydactyly are variably present, resulting in significant phenotypic heterogeneity and overlap with other ciliopathies. JS is also genetically heterogeneous, resulting from mutations in 13 genes. These factors render clinical/molecular diagnosis and management challenging. CC2D2A mutations are a relatively common cause of JS and also cause Meckel syndrome. The clinical consequences of CC2D2A mutations in patients with JS have been incompletely reported. Methods Subjects with JS from 209 families were evaluated to identify mutations in CC2D2A. Clinical and imaging features in subjects with CC2D2A mutations were compared with those in subjects without CC2D2A mutations and reports in the literature. Results 10 novel CC2D2A mutations in 20 subjects were identified; a summary is provided of all published CC2D2A mutations. Subjects with CC2D2A-related JS were more likely to have ventriculomegaly (p<0.0001) and seizures (p=0.024) than subjects without CC2D2A mutations. No mutation-specific genotype—phenotype correlations could be identified, but the findings confirm the observation that mutations that cause CC2D2A-related JS are predicted to be less deleterious than mutations that cause CC2D2A-related Meckel syndrome. Missense variants in the coiled-coil and C2 domains, as well as the C-terminal region, identify these regions as important for the biological mechanisms underlying JS. Conclusions CC2D2A testing should be prioritised in patients with JS and ventriculomegaly and/or seizures. Patients with CC2D2A-related JS should be monitored for hydrocephalus and seizures. [ABSTRACT FROM AUTHOR]

Objective: The postsynaptic density protein of excitatory neurons PSD-95 is encoded by discs large MAGUK scaffold protein 4 (DLG4), de novo pathogenic variants of which lead to DLG4-related synaptopathy. The major clinical features are developmental delay, intellectual disability (ID), hypotonia, sleep disturbances, movement disorders, and epilepsy. Even though epilepsy is present in 50% of the individuals, it has not been investigated in detail. We describe here the phenotypic spectrum of epilepsy and associated comorbidities in patients with DLG4-related synaptopathy., Methods: We included 35 individuals with a DLG4 variant and epilepsy as part of a multicenter study. The DLG4 variants were detected by the referring laboratories. The degree of ID, hypotonia, developmental delay, and motor disturbances were evaluated by the referring clinician. Data on awake and sleep electroencephalography (EEG) and/or video-polygraphy and brain magnetic resonance imaging were collected. Antiseizure medication response was retrospectively assessed by the referring clinician., Results: A large variety of seizure types was reported, although focal seizures were the most common. Encephalopathy related to status epilepticus during slow-wave sleep (ESES)/developmental epileptic encephalopathy with spike-wave activation during sleep (DEE-SWAS) was diagnosed in >25% of the individuals. All but one individual presented with neurodevelopmental delay. Regression in verbal and/or motor domains was observed in all individuals who suffered from ESES/DEE-SWAS, as well as some who did not. We could not identify a clear genotype-phenotype relationship even between individuals with the same DLG4 variants., Significance: Our study shows that a subgroup of individuals with DLG4-related synaptopathy have DEE, and approximately one fourth of them have ESES/DEE-SWAS. Our study confirms DEE as part of the DLG4-related phenotypic spectrum. Occurrence of ESES/DEE-SWAS in DLG4-related synaptopathy requires proper investigation with sleep EEG., (© 2023 International League Against Epilepsy.)

Explanation of the genetic basis of autism spectrum disorders has, for many decades, been a part of interest of researchers and clinicians. In recent years, thanks to modern molecular and cytogenetic techniques, a significant progress has been achieved in the diagnosis of genetic causes of autism. This applies particularly, but not exclusively, to those cases of autism that are accompanied by other clinical signs (i. e. complex phenotypes). The important clinical markers belong to different categories, and include congenital defects/anomalies, dysmorphism and macro-/microcephaly, to name the few. Thus, the choice of the diagnostic strategy depends on the clinical and pedigree information and, under Polish circumstances, the availability of specific diagnostic techniques and the amount of reimbursement under the National Health Service. Overall, the identification of the genetic causes of autism spectrum disorders is possible in about 10-30% of patients. In this paper the practical aspects of the use of different diagnostic techniques are briefly described. Some clinical examples and current recommendations for the diagnosis of patients with autism spectrum disorders are also presented. The point of view of a specialist in clinical genetics, increasingly involved, as part of the multidisciplinary care team, in the diagnostics of an autistic child has been demonstrated.

In the new classification of American Psychiatric Association - DSM-5 - a category of autistic spectrum disorders (ASD) was introduced, which replaced autistic disorder, Asperger syndrome, childhood disintegrative disorder and pervasive developmental disorder not otherwise specified. ASD are defined by two basic psychopathological dimensions: communication disturbances and stereotyped behaviors, and the diagnosis is complemented with the assessment of language development and intellectual level. In successive epidemiological studies conducted in 21 century the prevalence of ASD has been rising, and currently is estimated at 1% in general population. The lifetime psychiatric comorbidity is observed in majority of patients. The most common coexisting diagnoses comprise disorders ofanxiety-affective spectrum, and in about 1/3 of patients attention deficit/ hyperactivity disorders could be diagnosed. Prodromal symptoms of ASD may emerge before 12 months of life, however reliability of diagnosis at such an early age is poor. Several screening instruments, based on the parental and/or healthcare professional assessments may be helpful in ASD detection. However, structured interviews and observation schedules remain the gold standard of diagnosis.

Dystonias are a heterogeneous group of neurological disorders. In this paper we present clinical and molecular characteristics of inherited primary torsion dystonias. Clinical data and current concepts on the pathogenesis of dystonias with known molecular defect are presented in detail. Therapeutic options in patients with primary dystonias are also discussed.