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Although somatic mutations in Histone 3.3 (H3.3) are well-studied drivers of oncogenesis, the role of germline mutations remains unreported. We analyze 46 patients bearing de novo germline mutations in histone 3 family 3A (H3F3A) or H3F3B with progressive neurologic dysfunction and congenital anomalies without malignancies. Molecular modeling of all 37 variants demonstrated clear disruptions in interactions with DNA, other histones, and histone chaperone proteins. Patient histone posttranslational modifications (PTMs) analysis revealed notably aberrant local PTM patterns distinct from the somatic lysine mutations that cause global PTM dysregulation. RNA sequencing on patient cells demonstrated up-regulated gene expression related to mitosis and cell division, and cellular assays confirmed an increased proliferative capacity. A zebrafish model showed craniofacial anomalies and a defect in Foxd3-derived glia. These data suggest that the mechanism of germline mutations are distinct from cancer-associated somatic histone mutations but may converge on control of cell proliferation.

Purpose: Advances in fetal fraction amplification in prenatal cell-free DNA screening now allow for high-resolution detection of copy-number variants (CNVs). However, approaches to interpreting CNVs as part of a primary screen are still evolving and require consensus. Here, we present a conservative, patient-centered framework for reporting fetal CNVs., Methods: Syndromes described in the literature were evaluated for inclusion based on a definable minimal critical region, disease severity, penetrance, and age of onset. The reporting framework required that a CNV overlap a defined minimal critical region and/or that it be ≥5 Mb and contain at least 1 OMIM disease-associated gene. This framework was then applied to CNVs identified from a cohort of 313,544 prenatal cfDNA screening patient samples. Patient-friendly terminology describing syndrome phenotypes was developed by scientists with training in genetic counseling., Results: 65 syndromes met criteria for inclusion and represented the second most common class of CNVs in a retrospective cohort, more so than an established panel of microdeletions (1p36, 4p, 5p, 15q11.2-q13, and 22q11.2). Frequencies were concordant with reported syndrome incidence rates. The most common CNVs were those ≥5 Mb encompassing an OMIM disease gene(s)., Conclusion: This framework for genome-wide fetal-CNV reporting carefully prioritizes findings with the potential to affect reproductive decision making., Competing Interests: Conflict of Interest Samuel G. Cox, Ashley Acevedo, Anand Ahuja, Heather G. LaBreche, Maria P. Alfaro, Summer Pierson, Sarah Ratzel, Susan Hancock, Krista Moyer, and Dale Muzzey were employed by Myriad Genetics, Inc at the time of the study and received salaries and stocks as compensation. Thomas Westover is a paid consultant for Myriad Genetics, Inc, Natera, Labcorp, Illumina, and Billion to One., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)