Progressive Familial Intrahepatic Cholestasis (PFIC) is a rare liver disorder that, although typically present in childhood, can also occur in adulthood. Early diagnosis is crucial for appropriate clinical management, prognostic assessment, and therapeutic decision-making; however, it remains challenging due to phenotypic variability and the frequent identification of genetic variants of uncertain significance (VUS). Advances in next-generation sequencing (NGS) and whole-exome sequencing (WES) have improved the detection of disease-associated variants, revealing that the same genetic variants—often in a heterozygous state—may lead to adult-onset cholestatic disease, with milder or atypical presentations, while still conferring a significant risk of progressive liver injury and related complications. To assess the diagnostic yield and clinical utility of NGS panels and WES in adults with suspected PFIC or unexplained cholestatic liver disease, focusing on variant interpretation, emerging disease-associated genes, and clinical significance of VUS. A literature review was conducted to assess molecular diagnostics in adult cryptogenic cholestasis, with a focus on studies employing targeted NGS panels and WES. Selected studies were examined for diagnostic yield, variant classification, interpretive challenges, including VUS, and integration with clinical data. Data on patient demographics, sequencing techniques, and variant interpretation strategies were extracted to evaluate the current capabilities and limitations of genomic testing. From an initial search of 211 publications, 15 studies met the inclusion criteria, comprising five large adult cohorts and ten single-patient or trio-based reports. Across 72 patients, sequencing technologies identified 75 pathogenic or likely pathogenic variants, predominantly missense mutations, demonstrating high genetic heterogeneity. The most implicated genes included ABCB4, ABCB11, ATP8B1, TJP2, and USP53, with diagnostic yields ranging from 13.2% in large heterogeneous cohorts to substantially higher rates in carefully selected individual cases. VUS were identified in up to 67% of cases, highlighting the need for multidisciplinary interpretation integrating clinical, biochemical, and genetic data. Emerging evidence also implicated ciliopathy-associated genes such as DCDC2, NPHP3, PKHD1, TULP3, and TTC21B, expanding the genetic spectrum of adult cholestasis. Clinically, presentations ranged from mild biochemical abnormalities to progressive cholestasis, with pruritus being a common feature across studies. Comprehensive genetic testing significantly enhances diagnostic accuracy, informs prognosis, and guides individualized management in adults with cryptogenic cholestasis. Emerging evidence suggests that ciliopathy-associated genes may contribute to the genetic architecture of adult cholestatic disorders, further expanding the spectrum of disease-associated genes. However, the high prevalence of VUS remains a major challenge, highlighting the need for functional studies, longitudinal follow-up, and improved variant interpretation frameworks. As genomic technologies and analytical approaches continue to evolve, genetic testing is expected to play an increasingly central role in precision hepatology.
Amalia Conti, F. Gabrielli, S. Ferrari et al.· Diagnostics· 0 citations
We present a family of five siblings who came to our attention with a clinical and radiological diagnosis of familial hypomyelinating leukodystrophy. Despite brain white matter abnormalities being present in all siblings, the clinical phenotype was variable: the three brothers presented with a clear-cut late-onset spastic paraplegia, whereas the two sisters displayed only mild pyramidal signs. Molecular analysis revealed a single relevant variant shared by all affected siblings, namely the likely pathogenic variant c.659C>T (p.Ser220Phe) in the GJA1 gene. Variants in this gene are generally associated with oculodentodigital dysplasia (ODDD), an autosomal dominant condition characterized by distinctive facial features and anomalies of the eyes, teeth, and digits. Neurological features are reported in about 30% of cases. In this family, ODDD manifested as a predominantly neurological phenotype. Although a clear explanation for this uncommon presentation is lacking, shared genetic modifiers, the effect of the specific variant, and a possible patient-population bias may have contributed. This case highlights the wide phenotypic spectrum of CX43-related disorders and suggests the importance of testing the GJA1 gene in individuals with atypical presentations, including predominant or isolated neurological phenotypes such as late-onset spastic paraplegia. MRI findings may also provide a useful diagnostic clue when ODDD is suspected.
Irene Ambrosetti, Flavia Palombo, Diego D'Angeli et al.· International Journal of Mol...· 0 citations
Variants in BRSK2, encoding brain specific kinase-2, have recently been associated with an autosomal dominant neurodevelopmental disorder (NDD). We have assembled 52 cases with heterozygous BRSK2 variants and variable neurodevelopmental phenotypes with frequent neuropsychiatric and behavioral symptoms. The variant spectrum included 15 different truncating variants, seven (potential) splice variants, three structural variants, and 12 different missense variants. Of the missense variants, seven were in the kinase domain, and the others in the UBA and the KA1 domain or outside domains. Variants occurred de novo in 19 cases and were inherited in 18. We utilized Drosophila melanogaster as a model and assessed viability and performed climbing and bang sensitivity assays upon knockdown of the fly orthologue sff or upon overexpression of wildtype or mutant human BRSK2. Pan-neuronal knockdown of sff resulted in impaired locomotor behavior and seizure susceptibility. Ubiquitous or pan-neuronal overexpression of human wildtype BRSK2 in Drosophila resulted in lethality or locomotor impairment, respectively, indicating toxicity. Overexpressing mutant BRSK2 did not or incompletely affect viability and locomotor behavior for six of seven tested kinase domain missense variants and one KA1 domain variant, indicating a (partial) loss-of-function effect. Interestingly, overexpressing BRSK2 with the remaining missense variant from the kinase domain and the two most C-terminal missense variants resulted in possible gain of function. Our findings further delineate the clinical and molecular spectrum of BRSK2-associated NDD and provide further insights into the role of BRSK2/sff in nervous system function and dysfunction.
Palak Singhal, Tzung-Chien Hsieh, Nadja Ehmke et al.· European Journal of Human Ge...· 0 citations