PURPOSE: Genetic counseling (GC) is standard of care in genetic cancer risk assessment (GCRA). A rigorous assessment of the data reported from published studies is crucial to ensure the evidence-based implementation of GC. METHODS: We conducted a systematic review and meta-analysis of 17 patient-reported and health services-related outcomes associated with pre- and post-test GC in GCRA in accordance with PRISMA guidelines and GRADE methodology. RESULTS: 25 of 5393 screened articles met inclusion criteria. No articles reporting post-test GC outcomes met inclusion criteria. For patient-reported outcomes, pre-test GC significantly decreased worry, increased knowledge, and decreased perceived risk, but did not significantly affect patient anxiety, depression, decisional conflict, satisfaction, or intent to pursue genetic testing. For health-services outcomes, pre-test GC increased correct genetic test ordering, reduced inappropriate services, increased spousal support for genetic testing, and expedited care delivery, but did not consistently improve cancer prevention behaviors nor lead to accurate risk assessment. The GRADE certainty in the evidence was very low or low. No included studies elucidated GC effect on mortality, cascade testing, cost-effectiveness, care-coordination, shared decision-making, or patient time burden. CONCLUSION: The true impact of GC on relevant outcomes is not known due to low quality or absent evidence. While a meta-analysis found that pre-test GC had beneficial effects on knowledge, worry and risk perception, the certainty of this evidence was low according to GRADE methodology. Further studies are needed to support the evidence-based application of GC in GCRA.

PURPOSE: CNGA3 encoding the main subunit of the cyclic nucleotide-gated ion channel in cone photoreceptors is one of the major disease-associated genes for achromatopsia. Most CNGA3 variants are missense variants with the majority being functionally uncharacterized and therefore hampering genetic diagnosis. In light of potential gene therapy objective variant pathogenicity assessment is essential. METHODS: We established a medium-throughput aequorin-based luminescence bioassay allowing mutant CNGA3 channel function assessment via quantification of CNGA3 channel-mediated calcium influx in a cell culture system thereby enabling ACMG/AMP-based variant re-classification. RESULTS: We provide functional read-out obtained for 150 yet uncharacterized CNGA3 missense substitutions of which 55 were previously categorized as variants of uncertain significance (VUS) identifying 25 as functionally normal and 125 as functionally abnormal. These data enabled the ACMG/AMP-based variant re-classification of 52/55 VUS as either benign, likely benign or likely pathogenic reaching a VUS re-classification rate of 94.5%. CONCLUSION: Our aequorin-based bioassay allows functionally ensured clinical variant interpretation for 150 CNGA3 missense variants enabling and supporting VUS re-classification and assuring molecular diagnosis to patients affected by CNGA3-associated achromatopsia, hereby identifying patients eligible for future gene therapy trials on this disease.

PURPOSE: ATP2B2 encodes the variant-constrained plasma-membrane calcium-transporting ATPase-2, expressed in sensory ear cells and specialized neurons. ATP2B2/Atp2b2 variants were previously linked to isolated hearing loss in patients and neurodevelopmental deficits with ataxia in mice. We aimed to establish the association between ATP2B2 and human neurological disorders. METHODS: Multinational case recruitment, scrutiny of trio-based genomics data, in-silico analyses, and functional variant characterization were performed. RESULTS: We assembled seven individuals harboring rare, predicted deleterious heterozygous ATP2B2 variants. The alleles comprised five missense substitutions affecting evolutionarily conserved sites and two frameshift variants in the penultimate exon. For six variants, a de-novo status was confirmed. Unlike described patients with hearing loss, the individuals displayed a spectrum of neurological abnormalities, ranging from ataxia with dystonic features to complex neurodevelopmental manifestations with intellectual disability, autism, and seizures. Two cases with recurrent amino-acid variation showed distinctive overlap with cerebellar atrophy-associated ataxia and epilepsy. In cell-based studies, all variants caused significant alterations in cytosolic calcium handling with both loss- and gain-of-function effects. CONCLUSION: Presentations in our series recapitulate key phenotypic aspects of Atp2b2-mouse models and underline the importance of precise calcium regulation for neurodevelopment and cerebellar function. Our study documents a role for ATP2B2 variants in causing heterogeneous neurodevelopmental and movement-disorder syndromes.

PURPOSE: To summarize the results of first year implementation of pan-ethnic screening testing for Duchenne Muscular Dystrophy (DMD), and present the ensuing challenges. METHODS: Data acquisition for this study was performed by retrospective search of Ministry of Health registry for reports of all laboratories performing genetic screening tests. DMD testing was performed by multiplex ligation-dependent probe amplification technology (MLPA). In case of single exon deletion, sequencing of the specific exon was performed to rule out underlying single nucleotide variant. RESULTS: Of overall 85,737 DMD tests, 82 clinically significant findings were noted (0.095%, or 1:1046 women). In addition, 80 findings with uncertain clinical significance were detected (0.093%, or 1:1072), as well as 373 cases (0.4%, or 1:230) of single exon deletions subsequently identified as false-positives due to underlying single nucleotide variant, mostly variants in exon 8 in North African Jewish population, and in exon 48 in Arab Muslim population. CONCLUSION: Interpretation of population-based DMD carrier-screening is complex, occasionally requiring additional genetic testing methods and ethical considerations. Multicenter data registry, including ethnic origin and familial segregation in selected cases, is crucial for optimal definition of the results during genetic counseling and informed decisions regarding prenatal testing.