Neurodevelopmental disorders arising from mutations in RNA-processing factors are increasingly recognized but remain mechanistically underexplored. Here, we identify that variant (c.485A>C; p.Lys137Gln) in DDX39A in a 7-month-old proband presenting with global developmental delay, microcephaly, seizures, hypotonia, and brain atrophy with corpus callosum thinning. DDX39A encodes a DEAD-box RNA helicase essential for mRNA splicing and export via the TREX complex. Functional studies in proband-derived fibroblasts revealed that while transcript and protein levels of DDX39A-K137Q were unaffected, the mutant protein displayed aberrant nuclear clumping and failed to interact with the TREX component THOC1. Structural modeling demonstrated that Lys137 mediates critical inter- and intra-molecular interactions, which are disrupted by the K137Q substitution. This loss destabilizes the DDX39A-THOC1 interface, impairing TREX complex integrity. The mutant cells exhibited severe nuclear morphological abnormalities, disrupted nuclear lamina organization, and increased cell death. Transcriptomic network analysis and gene ontology revealed enrichment of DDX39A interactions in mRNA export, splicing, and nucleocytoplasmic transport-functions essential for neuronal development. Temporal and regional brain expression data showed that DDX39A is highly expressed during early postnatal life and across multiple brain regions, indicating its importance in early brain maturation. Our findings establish DDX39A-K137Q as a pathogenic variant that impairs nuclear RNA processing and structural homeostasis, leading to a severe neurodegenerative phenotype. This study identifies the role of RNA helicases in neurodevelopment and explores DDX39A as a novel gene implicated in pediatric neurodegenerative disease.

Osteogenesis imperfecta (OI) is a heterogeneous group of genetic diseases characterized by bone fragility and low bone mass. We report the identification of two unrelated families with OI of Bashkir origin-one with homozygous, the other with compound heterozygous probably pathogenic variants of the P3H1 gene, as well as one case of heterozygous carriage in a patient with clinical manifestations that do not correspond in severity to type VIII OI. Thus, an ethnospecific previously undescribed population aspect of the prevalence of recessive pathogenic variants p.Glu351Ter, p.Gly650Arg, 1720 + 4G>A in the P3H1 gene associated with various clinical phenotypes has been identified.

ABSTRACTMiller syndrome (MIM#263750) is a rare autosomal recessive acrofacial dysostosis associated with biallelic DHODH variants. Since the identification of the gene in 2010, five case reports have described a variable phenotype in only nine individuals from eight families. We present a cohort of 10 individuals from seven families affected by Miller syndrome, spanning the prenatal stage to 46 years of age. We report on the largest cohort of Miller syndrome to date, which highlights novel findings, including optic atrophy in multiple members of one consanguineous family. The typical postaxial limb defects, including the absence of the 5th digit, were consistent with prior descriptions, but we highlighted the frequent involvement of preaxial structures (thumb and tibial hypoplasia). A higher incidence of camptodactyly and the presence of facial nevus in two patients were notable findings. Congenital heart defects, primarily atrial septal defects, were common, and all living individuals had normal neurodevelopment. This cohort expands the phenotypic spectrum of Miller syndrome associated with variation in DHODH, presenting new findings such as preaxial involvement and facial nevus simplex. Optic atrophy in one family could prompt screening of other cases. Early prenatal diagnosis, particularly in the presence of cardinal limb and cardiac malformations, is crucial for management and genetic counseling.

of clinical and molecular findings in patients with biallelic variants in PDCD6IP.

SLC25A42 encodes a mitochondrial carrier that is responsible for the import of CoA into mitochondria. Biallelic pathogenic variants in SLC25A42 have been associated with a recently described mitochondrial disorder characterized by encephalomyopathy with variable severity. To date, 24 affected individuals from 16 different families have been reported. Most are of Arab descent who harbor the founder variant in SLC25A42 (c.871A>G, p.Asn291Asp). In this report, we present 23 additional individuals from 19 unrelated families and their clinical, radiological, and molecular findings. We show again that SLC25A42-related mitochondrial disorder is associated with extremely variable severity. Some individuals with mild presentation may be unrecognized, while others are prone to metabolic decompensations with neuro-regression and irreversible neurological insult, making early diagnosis important.

TMEM17 encodes a transition zone protein essential for ciliary function. Three cases with homozygous variants in TMEM17 in primary ciliopathies (Joubert and Oral-Facial-Digital syndrome) have been reported. We investigated whether biallelic TMEM17 variants contribute to primary ciliopathies. We queried our Biodatabank and evaluated the gene-disease relationship (GDR) according to the ClinGen recommendations. Four unrelated patients (four families) were identified with a clinical diagnosis of Meckel-Gruber syndrome (MGS) and novel homozygous variants: NM_198276.3:c.4del p.(Glu2Serfs*58); NM_198276.3:c.366dup p.(Pro123Thrfs*9); and NM_198276.3:c.368C>G p.(Pro123Arg). A fifth family lost three foetuses with MGS phenotype, both parents are heterozygote carriers (NM_198276.3:c.4del p.(Glu2Serfs*58)) but biological material from the foetuses was not available. The cases in this study had a severe prenatal phenotype, including encephalocele, polycystic kidney dysplasia, and polydactyly, leading to early lethality. This study strengthens the gene-disease association of TMEM17, upgrading it from "limited" to "moderate." We expand the phenotypic spectrum, ranging from MGS-with prenatal onset and early lethality-to Oral-Facial-Digital and Joubert syndromes. Our findings indicate that loss-of-function variants may underlie the most severe TMEM17 ciliopathy manifestations, suggesting a potential genotype-phenotype correlation.

ABSTRACTCell‐free DNA (cfDNA) screening for fetal aneuploidy is typically offered from 10 weeks of gestational age (GA) onward. Fetal fraction (FF) enrichment may enable screening before 10 weeks with a low failure rate. This study aimed to assess the feasibility of cfDNA screening with in vitro enrichment before 10 weeks of gestation. 435 pregnant women were recruited between 7w0d and 9w6d of GA (EARLY samples) and scheduled for a second cfDNA sample after 11 weeks of GA (12w+ samples). 371 women provided both an EARLY and a 12w+ sample, and we compared cfDNA results between EARLY and 12w+ samples and sex at birth. For sex determination using cfDNA, EARLY, and 12w+ samples were 100% concordant with clinical sex at birth. In 170 male pregnancies, EARLY samples 5.9% had FF < 4% after enrichment. Seven aneuploidies were observed early, but eight at 12+ weeks (one false positive after invasive diagnostic testing). We observed 4.4% spontaneous abortions between the EARLY and 12w+ sampling. Our findings suggest that in vitro fetal enrichment provides sufficient cfDNA for reliable prenatal cfDNA screening results as early as 8 weeks, but one limitation lies in the high proportion of spontaneous abortions before 12w0d.

Loss-of-function variants in FREM1 have been demonstrated in Manitoba oculotrichoanal syndrome (MOTA) and bifid nose, renal agenesis, and anorectal malformations (BNAR) syndrome, but the broader phenotypic spectrum of FREM1 variants remains incompletely characterized. In this study, we report compound heterozygous variants in a prenatal case of bilateral renal agenesis. Exome sequencing revealed biallelic FREM1 variants: c.5622G>A (p.Trp1874*) and c.3274+4A>G (p.Gly1030_Ile1091del). Minigene and bioinformatic analyses confirmed that the splice site variant induces aberrant splicing and alters transcriptional expression levels. This finding underscores the crucial role of non-canonical splice site variants in FREM1 in the pathogenesis of bilateral renal agenesis.

ABSTRACTJones syndrome (JS) is an ultra‐rare autosomal dominant condition characterized by gingival fibromatosis and progressive sensorineural hearing loss. It has been recently demonstrated in members of a Finnish family to co‐segregate with heterozygosity for a frameshift variant in the fifth and last exon of the repressor element 1‐silencing transcription factor gene (REST). Here, we report the first Italian family in which JS was diagnosed in the proband, a 38‐year‐old woman, and in her mother. Exome Sequencing identified in both, but not in clinically unaffected members of the family (i.e., a sister and the brother of the proband), the heterozygous pathogenic variant c.2645T>G (p.Leu882*) in exon‐5 of the REST gene. This study confirms that exon‐5 REST variants cause JS.

ABSTRACTChronic kidney disease (CKD) has a genetic origin in 10% of patients. The most effective and cost‐beneficial genetic testing methodology is debated. A multicenter, retrospective analysis of 692 patients with panel genetic testing (44 genes) evaluated the diagnostic yield, independent predictors of genetic diagnoses, and clinical impact. Diagnostic variants identified totaled 252, resulting in a 36% yield. The highest yields were associated with cystic disease (49%). No diagnostic variants were identified in unknown CKD. Independent clinical predictors of diagnosis were clinical presentation, family history, and early disease onset. Genetic diagnoses confirmed clinical suspicion in 70%, defined the diagnosis in 23%, and altered clinical diagnosis in 7%. Despite study limitations, a 44 gene panel seems to have a similar diagnostic yield as larger panels and whole‐exome sequencing (WES) approaches. Patient selection based on independent predictors of genetic diagnosis may further increase diagnostic yield and cost‐effectiveness, especially useful in cost‐restricted contexts.