Background Genetic testing for likely pathogenic/pathogenic variants (PV) in BRCA1, BRCA2, and other cancer-associated genes plays a critical role in the diagnosis, prognosis, and management of breast and ovarian cancer (BCOC). Extending testing to healthy family members (HFM) of affected individuals enables early prevention strategies and timely referrals for enhanced screening, thereby improving cancer risk management. This study aimed to characterize the demographic profile and genetic findings among HFMs of BCOC patients in Estonia within routine clinical practice. Methods A retrospective analysis was conducted on 3,472 HFMs who underwent genetic testing. Demographic data were collected, and the presence of PVs was assessed. Statistical comparisons were made between individuals with and without known familial PVs, and between male and female participants, using descriptive statistics and proportion comparisons. Results Of the 3,472 HFMs tested, 87.6% were female and 12.4% male, with a mean age of 41.1 ± 13.0 years. Notably, 78.6% were younger than 51 years, the typical age for initiating standard screening. PVs were identified in 683 individuals (19.7%). Among those with a known familial PV (n = 1,009), 41.8% were carriers, compared to 8.0% among those without a known familial PV (n = 2,408). Males were more likely to be tested when a familial PV was known (26.6%) than when it was not (6.6%), and 34.0% of tested males were PV carriers. PVs were found in 23 different genes, with BRCA1/2 accounting for 58.4% of all PVs, followed by ATM, BRIP1, CHEK2, and PALB2. Conclusion The findings highlight the value of genetic testing in identifying at-risk individuals among HFMs of BCOC patients. The predominance of BRCA1/2 variants and the significant detection rate among younger individuals underscore the importance of early testing. The expansion of HFM testing in Estonia reflects increased public awareness and clinical integration of genetic risk assessment in cancer prevention strategies.
M. Tooming, Kadri Rekker, K. Toome et al.· Frontiers in Genetics· 0 citations
Pathogenic variants in AGO2, encoding a central component of the RNA-induced silencing complex (RISC), cause the neurodevelopmental disorder Lessel-Kreienkamp syndrome (LESKRES). The variant spectrum and associated molecular mechanisms underlying phenotypic variability and disease severity remain incompletely understood. We investigated 45 newly identified individuals carrying 33 distinct AGO2 variants, 30 of which were previously unreported. Phenotypic data from these and previously reported cases (n = 70) were integrated to delineate the LESKRES-associated clinical spectrum and genotype–phenotype correlations. Functional studies included shRNA-based silencing, co-immunoprecipitation, subcellular localization, and sequencing of AGO2-bound miRNAs. All individuals presented with a neurodevelopmental disorder of variable severity. Delayed speech and language development (97%), intellectual disability (97%), and motor delay (93%) were the most consistent features, frequently accompanied by muscular hypotonia, autistic traits, attention deficit hyperactivity disorder, visual impairment and structural brain anomalies. Systemic manifestations, including skeletal, craniofacial, cardiac, and male urogenital anomalies were common, underscoring AGO2’s multisystemic role. Moreover, we report occurrence of gonadal mosaicism and reveal the presence of interfamilial and variant-specific clinical heterogeneity. Variants clustered in defined regions of AGO2, including the L1 loop, helix-7, and multiple loops of the PIWI domain, highlight structural hotspots critical for RISC activity. Not all pathogenic variants impaired shRNA-mediated silencing; this was restricted to p.(Arg714Trp) and p.(Asn729His). Biochemical analyses revealed that p.(Asp619Asn) impaired GW182 binding and P-body assembly. Variants p.(Arg506Gln), p.(Glu531Gln) p.(Gly604Arg) and p.(Asp619Asn), reduced C-terminal phosphorylation, implicating defective AGO2 recycling. AGO2–miRNA co-immunoprecipitation and sequencing demonstrated variant-specific perturbations in miRNA association, strand selectivity, and isomiR generation. Variants near the hinge of the helix-7 region, especially p.(Phe182del), induced extensive changes in miRNA association and 3′-end modification, suggesting impaired anchoring within the miRNA-binding pocket. Our findings substantially broaden the clinical and molecular landscape of LESKRES, establishing AGO2 as a pivotal regulator of neurodevelopment whose structural integrity is essential for precise miRNA-mediated gene regulation. Pathogenic variants disrupt distinct interconnected processes: P-body association, phosphorylation-dependent turnover, and miRNA interactions, culminating in dysregulated post-transcriptional gene silencing. These mechanistic insights link specific structural perturbations in AGO2 to graded clinical outcomes and underscore the critical role of AGO2 conformational dynamics in human neurodevelopment.
Debora Tibbe, Christina Kiel, Olena Ielesicheva et al.· Genome Medicine· 0 citations