Familial communication and cascade testing following elective genomic testing.

Familial communication of results and cascade genetic testing (CGT) can extend the benefits of genetic screening beyond the patient to their at-risk relatives. While an increasing number of health systems are offering genetic screening as an elective clinical service, data are limited about how often results are shared and how often results lead to CGT. From 2018 to 2022, the Sanford Health system offered the Sanford Chip, an elective genomic test that included screening for medically actionable predispositions for disease recommended by the American College of Medical Genetics and Genomics for secondary findings disclosure, to its adult primary care patients. We analyzed patient-reported data about familial sharing of results and CGT among patients who received Sanford Chip results at least 1 year previously. Among the patients identified with medically actionable predispositions, 94.6% (53/56) reported disclosing their result to at least one family member, compared with 46.7% (423/906) of patients with uninformative findings (p < 0.001). Of the patients with actionable predispositions, 52.2% (12/23) with a monogenic disease risk and 12.1% (4/33) with a carrier status reported that their relatives underwent CGT. Results suggest that while the identification of monogenic risk during elective genomic testing motivates CGT in many at-risk relatives, there remain untested at-risk relatives who may benefit from future CGT. Findings identify an area that may benefit from increased genetic counseling and the development of tools and resources to encourage CGT for family members.

Interstitial Chromosome 3p13p14 Deletions: An Update and Review.

Deletions of proximal chromosome 3p13p14 are infrequent chromosomal alterations. Variable sizes and breakpoints have been reported in patients with a wide range of phenotypes that are evolving as additional cases are reported. The routine use of high-density chromosomal microarrays (CMA) has allowed the identification of many more cases of this disorder and clinical phenotyping shows evidence for an emerging profile among patients with overlapping deletions of 3p13p14. Here, we review the currently reported cases, their phenotypes and where available, the genomic intervals delineated by CMA. Surprisingly, we found that a significant number of proximal chromosome 3p deletions involve structural rearrangements, especially insertions, that have been identified in balanced parental chromosome complements. This region is historically known as a common human chromosomal fragile site, although an underlying genomic mechanism related to its architecture has not been identified. We conclude that identification of an interstitial 3p deletion in a proband by CMA should prompt consideration of further structural chromosomal evaluation using more traditional cytogenetic techniques. While the variability in breakpoints does not suggest a unifying underlying mechanism for these alterations, identification of the haploinsufficient genes in each patient's deletion interval and their developmental roles can guide genotype-phenotype correlations and impact clinical management.