The detection of a strong episignature for Chung-Jansen syndrome, partially overlapping with Börjeson-Forssman-Lehmann and White-Kernohan syndromes.

Chung-Jansen syndrome is a neurodevelopmental disorder characterized by intellectual disability, behavioral problems, obesity and dysmorphic features. It is caused by pathogenic variants in the PHIP gene that encodes for the Pleckstrin homology domain-interacting protein, which is part of an epigenetic modifier protein complex. Therefore, we hypothesized that PHIP haploinsufficiency may impact genome-wide DNA methylation (DNAm). We assessed the DNAm profiles of affected individuals with pathogenic and likely pathogenic PHIP variants with Infinium Methylation EPIC arrays and report a specific and sensitive DNAm episignature biomarker for Chung-Jansen syndrome. In addition, we observed similarities between the methylation profile of Chung-Jansen syndrome and that of functionally related and clinically partially overlapping genetic disorders, White-Kernohan syndrome (caused by variants in DDB1 gene) and Börjeson-Forssman-Lehmann syndrome (caused by variants in PHF6 gene). Based on these observations we also proceeded to develop a common episignature biomarker for these disorders. These newly defined episignatures can be used as part of a multiclass episignature classifier for screening of affected individuals with rare disorders and interpretation of genetic variants of unknown clinical significance, and provide further insights into the common molecular pathophysiology of the clinically-related Chung-Jansen, Börjeson-Forssman-Lehmann and White-Kernohan syndromes.

Developmental epileptic encephalopathy in DLG4-related synaptopathy.

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.

Perceptions of reproductive healthcare providers regarding their involvement in offering expanded carrier screening in fertility clinics: a qualitative study.

RESEARCH QUESTION: What are the main arguments of reproductive healthcare providers in favour or against their involvement in offering expanded carrier screening (ECS) for recessive disorders at fertility clinics in the Netherlands? DESIGN: Semi-structured interview study with 20 reproductive healthcare providers between May 2020 and January 2021. Participants included 11 gynaecologists, seven fertility doctors, one nurse practitioner and one clinical embryologist, recruited from academic medical centres (n = 13), peripheral facilities associated with academic centres (n = 4), and independent fertility treatment centres (n = 3) in the Netherlands. An interview guide was developed, and thematic content analysis was performed using ATLAS.ti software. RESULTS: Arguments of reproductive healthcare providers in favour of their potential involvement in offering ECS included: (i) opportunities offered by the setting; (ii) motivation to assist in reproduction and prevent suffering; and (iii) to counter unwanted commercialization offers. Arguments against involvement included: (i) lack of knowledge and familiarity with offering ECS; (ii) insufficient staff and resources, and potential high costs for clinics and/or couples; (iii) the emotional impact it may have on couples; (iv) perceived complexity of counselling and expected elongation of waiting lists; and (v) expected low impact on reducing the burden of diseases. Participants felt that more evidence and research on the costs-benefits, implications and demand are needed prior to their involvement. CONCLUSION: While agreeing that the field of medically assisted reproduction provides a unique opportunity to offer ECS, reproductive healthcare workers feel a lack of capability and limited motivation to offer ECS to all or a selection of couples at their fertility clinics.

Medullary Sponge Kidney and Its Relationship with Primary Distal Renal Tubular Acidosis: Case Reports and a Comprehensive Genetics-First Approach.

Medullary sponge kidney (MSK) is a description of radiographic features. However, the pathogenesis of MSK remains unclear. MSK is supposed to be the cause of secondary distal renal tubular acidosis (dRTA), although there are case reports suggesting that MSK is a complication of primary dRTA. In addition to these reports, we report 3 patients with metabolic acidosis and MSK, in whom primary dRTA is confirmed by molecular genetic analyses of SLC4A1 and ATP6V1B1 genes. With a comprehensive genetics-first approach using the 100,000 Genomes Rare Diseases Project dataset, the association between MSK and primary dRTA is examined. We showed that many patients with MSK phenotypes are genetically tested with a gene panel which does not contain dRTA-associated genes, revealing opportunities for missed genetic diagnosis. Our cases highlight that the radiological description of MSK is not a straightforward disease or clinical phenotype. Therefore, when an MSK appearance is noted, a broader set of causes should be considered including genetic causes of primary dRTA as the underlying reason for medullary imaging abnormalities.