Rust, Laura

ABSTRACT Background Li Fraumeni syndrome (LFS) is a hereditary multi‐cancer syndrome caused by alterations in TP53 (MIM# 151623). Next generation sequencing (NGS) allows for the detection of TP53 variants at lower variant allele frequencies (VAFs). A TP53 variant with a VAF < 50% may represent mosaic LFS, aberrant clonal expansion (ACE), or possible circulating tumor DNA. Differentiation among these conditions is important for optimal patient management. Methods Genetic testing was performed using a custom gene panel, with an average read depth of 350× (range 166–553×). DNA extracted from four different tissues (blood, saliva, cultured skin fibroblasts, and colon) was sequenced. Results Here, we describe an adult female patient with a history of an adrenocortical neoplasm and osteosarcoma, diagnosed at 2 and 16 years of age, respectively. Testing of peripheral blood identified a pathogenic TP53 variant, c.733G>A, p.(Gly245Ser) (NM_000546.6); however, subsequent in vitro fertilization with preimplantation genetic testing for monogenic disorders (PGT‐M) did not identify this TP53 variant in any of nine embryos tested. Testing for possible mosaicism in the proband was performed on four different specimens, revealing variable VAFs of the TP53 variant (saliva: 44%; blood: 31%; cultured skin fibroblasts: 18%; and colon tissue: 9%). These results suggest a post‐zygotic event, consistent with mosaic LFS rather than ACE. Conclusion This case highlights the complexity of interpreting mosaic variants in the TP53 gene, and we propose a testing algorithm to aid in the delineation of this phenomenon when relaying cancer and reproductive risk information in the context of mosaicism.

AbstractAxenfeld‐Rieger Syndrome (ARS) type 1 is a rare autosomal dominant condition characterized by anterior chamber anomalies, umbilical defects, dental hypoplasia, and craniofacial anomalies, with Meckel's diverticulum in some individuals. Here, we describe a clinically ascertained female of childbearing age with ARS for whom clinical targeted sequencing and deletion/duplication analysis followed by clinical exome and genome sequencing resulted in no pathogenic variants or variants of unknown significance in PITX2 or FOXC1. Advanced bioinformatic analysis of the genome data identified a complex, balanced rearrangement disrupting PITX2. This case is the first reported intrachromosomal rearrangement leading to ARS, illustrating that for patients with compelling clinical phenotypes but negative genomic testing, additional bioinformatic analysis are essential to identify subtle genomic abnormalities in target genes.

Abstract Career shadowing can be a valuable opportunity for individuals to experience the daily activities of a working professional. However, there is no published research regarding the impact of shadowing for individuals hoping to pursue a career as a genetic counselor (GC) (termed ‘shadowees’). Additionally, little is known about the impact of shadowing on practicing GCs, nor the value of shadowing in the application and admission process for genetic counseling graduate programs. For this study, three independent surveys were developed and sent to three stakeholder groups: shadowees in the Minnesota Genetic Counseling Experience Program, program directors within the Association of Genetic Counseling Program Directors, and members of the National Society of Genetic Counselors. Quantitative and qualitative analyses were performed on responses. The survey of shadowees ( n = 55) found that the majority believed that shadowing had either a ‘very’ or ‘somewhat positive’ impact on their decision to become a GC and on their application to a genetic counseling graduate program (81.8% and 91.3%, respectively). Of the participating program director respondents ( n = 43), the majority indicated that having shadowing experience was either ‘moderately’ or ‘extremely important’ in offering an interview or for acceptance into a graduate program (63% and 56%, respectively). While programs differ in evaluation of shadowing experiences, most program directors indicated that an applicant's ability to speak to their shadowing experience was the most important factor in admissions consideration (71%). Among the GCs surveyed ( n = 325), 69.2% have hosted shadowees; of these, 82.7% indicated that hosting a shadowee decreases their efficiency at work. Despite this drawback, the majority of respondents expressed a willingness and motivation to host shadowees to help the shadowee (64.8%) and to promote the genetic counseling profession (32.6%). These findings suggest the need for additional research and the development of resources for GCs to increase access of career shadowing.