Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in a wide range of outcomes characterized by a high heterogeneity in both symptomatology and susceptibility to the disease. In such a perspective, COVID-19 may be considered as a multifactorial disease featured by the interaction between the environment, which is the virus itself, and the genetic profile of the host. Our analysis aimed at investigating the transmission dynamics of SARS-CoV-2 within families whose members responded in different ways to the infection, although the exposure was common to the entire group and occurred before the availability of any vaccine. The goal was to understand how the genetic background of each subject can influence the viral infection outcome and hence the above-mentioned clinical variability. We performed a segregation analysis in 19 Italian families with a designed custom panel of 42 genes involved in immunity and virus entry and which have also been shown to be related to SARS-CoV-2 host response. We carried out both a familial segregation analysis and a global statistical analysis. In the former we identified eighteen risk variants co-segregating with a COVID-positive status and six variants with a possible protective effect. In addition, sixteen variants showed a trend of association to a severe phenotype. Together with common SNPs, we detected private rare variants that may also provide insight into the observed clinical COVID-19 heterogeneity. The global statistical analysis confirmed statistically significant positive associations between SARS-CoV-2 individual response and some specific gene variants identified in familial analysis. In conclusion our data confirm that the clinical expression of COVID-19 is markedly influenced by the host genetic profile both with a mendelian transmission pattern and a polygenic architecture.

Background/Objectives: Hereditary hearing loss (HHL) is a genetically heterogeneous condition, involving more than 150 genes in non-syndromic cases and associated with over 400 distinct disorders in syndromic forms. Although whole-exome sequencing (WES) has markedly increased diagnostic yield, a substantial number of cases remain unsolved, often due to intronic variants that affect splicing and are difficult to interpret. This study aimed to characterize the potential impact of intronic variants predicted to alter splicing in families affected by HHL. Methods: The effect of seven intronic variants, previously identified in a diagnostic setting by WES within ADGRV1, ATP11A, GSDME, OTOF, OTOGL, and USH2A genes, was evaluated. To functionally validate these predictions, in vitro minigene splicing assays were subsequently performed. Results: All the identified variants were predicted to disrupt normal RNA splicing. The functional studies with minigene assays confirmed this observation and showed that the tested variants induced both exon skipping and activation of cryptic splice sites. In five out of seven cases, these splicing alterations caused a frameshift and introduced a premature termination codon, ultimately resulting in nonsense-mediated mRNA decay and protein degradation. Conclusions: This study expands the mutational spectrum of HL-related genes and highlights the importance of integrating in silico predictions with minigene assays. Such a combined approach is crucial for accurate interpretation of splicing variants, particularly when patient-derived RNA samples are unavailable.

Background: North Carolina Macular Dystrophy (NCMD) is a non-progressive inherited macular dystrophy characterized by marked phenotypic variability. The genetic etiology of NCMD remains largely unknown, and only a limited number of families have been reported in Europe. Methods: We performed an in-depth investigation of an Italian family affected by NCMD using an integrated approach that combined SNP-array analysis, whole-exome sequencing, and long-read whole-genome sequencing. Additionally, we conducted a comprehensive review of NCMD-related literature. Results: We identified a novel 98 Kb duplication involving both PRDM13 and CCNC genes in a three-generation kindred, where the proband exhibited severe macular alterations, while all other affected family members presented with a milder clinical phenotype. A review of the literature suggests different genotype–phenotype correlations and similar penetrance for duplications and single-nucleotide variants (SNVs) in described families. Specifically, smaller duplications may be associated with more severe phenotypes, while SNVs exhibit high phenotypic variability. Conclusions: In this study, we describe the first NCMD Italian family, in which the integration of second- and third-generation sequencing methods enabled the identification of a novel pathogenic PRDM13 and CCNC duplication, thereby expanding the mutational spectrum of NCMD. Overall, these findings, together with the literature review, highlight the importance of selecting appropriate genetic testing approaches that allow the detection of non-coding variants and CNVs and thus enable accurate diagnosis and effective clinical management of patients and their families.

Glycosylphosphatidylinositol (GPI) biosynthesis defect 11 (GPIBD11), part of the heterogeneous group of congenital disorders of glycosylation, is caused by biallelic pathogenic variants in PIGW. This rare disorder has previously been described in only 12 patients. We report four novel patients: two sib fetuses with congenital anomalies affecting several organs, including the heart; a living girl with tetralogy of Fallot, global developmental delay, behavioral abnormalities, and atypic electroencephalography (EEG) without epilepsy; a girl with early-onset, treatment-resistant seizures, developmental regression, and recurrent infections, that ultimately passed away prematurely due to pneumonia. We also illustrate evolving facial appearance and biochemical abnormalities. We identify two novel genotypes and the first frameshift variant, supporting a loss-of-function pathogenic mechanism. By merging our cohort with patients documented in the literature, we deeply analyzed the clinical and genetic features of 16 patients with PIGW-related disorder, revealing a severe multisystemic condition deserving complex management and with uncertain long-term prognosis. We consider the role of PIGW within the critical 17q12 region, which is already associated with genomic disorders caused by deletion or duplication and characterized by variable expressivity. Finally, we discuss PIGW dosage effects and a second hit hypothesis in human development and disease.

COVID-19 may be considered a multifactorial disease caused by the interaction between the virus itself, as the environmental contribute, and the genetic background of the host. SARS-CoV-2 infection occurs through the interaction between the spike protein and ACE2, a receptor in the host cells. Clinically, COVID-19 is characterized by a high heterogeneity in symptomatology ranging from asymptomatic to severe symptoms, and even worsening to death. This variability relies on the host genomic profile and other individual comorbidities. We performed exome analysis in one family displaying a variable spectrum of SARS-CoV-2 infection despite a common exposure. After segregation analysis, we found that the c.446C>T p.(S149L) in MAS1 gene was exclusively present in the individual with severe COVID-19, who died because of pneumonia and multiple thrombotic events. MAS1 encodes a receptor for Ang1–7 in the renin-angiotensin system (RAS) with an anti-inflammatory, anti-fibrotic and anti-angiogenic effect. We hypothesize that downregulation of RAS, due to this rare variant, might impair the protective effect and concur to the clinical severity of the disease. Our results support the protective role of the ACE2/Ang-(1–7)/Mas1 axis and the potential danger of its dysregulation leading to severe COVID-19 disease; if further confirmed, these findings will be useful for management of critically ill patients.

Background: Foetal structural abnormalities can be detected in approximately 3% of all pregnancies and frequently remain without a genetic diagnosis. This study aims to apply an integrated approach with the final goal of providing a molecular diagnosis in the challenging Italian setting of early termination of pregnancy. Methods: In a cohort of 86 foetuses, post-mortem dysmorphological examination, radiological assessments, and molecular autopsy through Whole-Exome Sequencing—WES—analysis were performed. Results: Forty-two foetuses were phenotypically classified as presenting a single major malformation (i.e., central nervous system, skeletal, urogenital, or cardiac anomalies, or fluid accumulation), while 44 foetuses presented multiple malformations and/or dysmorphic features. Overall, WES provided a diagnostic yield of 26.7%; additionally, seven Variants of Uncertain Significance (VUS) potentially liked to the foetal phenotype were identified. The highest detection rate was achieved for foetuses presenting a single major urogenital (50%) or skeletal (42.9%) malformation, followed by foetuses presenting multiple malformations (27.3%). Peculiar results of particular interest were (1) the identification of two splicing variants (within the INPPL1 and RHOA genes), functionally characterised through minigene assay, which contributed to evaluate their pathogenicity, and (2) the identification of a novel de novo missense ZNF292 variant (NM_015021.3:c.6325A>C p.(Ser2109Arg)) in a foetus affected by corpus callosum hypoplasia. The ZNF292 gene is associated with the Intellectual developmental disorder, autosomal dominant 64 and this finding represents the first report of prenatally detected anomalies of the central nervous system in a foetus carrying a ZNF292 variant. Conclusions: This study underlines the diagnostic utility of an integrated approach to achieve a precise genetic diagnosis for structural foetal abnormalities, thus providing families with precise recurrence risk estimations and detailed options about future pregnancies. Additionally, a systematic implementation of this strategy could be crucial to better characterise new variants and discover new genes involved in embryonic and foetal development.