When there is a specific condition suspected based on clinical features or where clinical criteria are available, targeted testing is more appropriate than broad panel or genomic testing. The advantages of targeted testing are that the gene(s) or chromosomal region(s) being tested are well known to be associated with specific risks, often have management guidelines available if a pathogenic variant is found, and it is simpler to convey the specific limitations and benefits of doing targeted testing. The analytic validity, clinical validity and clinical utility are important domains in genetic testing evaluation and are easier to determine for a targeted test rather than for a broad or genomic test where the phenotype may not be anticipated, or the gene may be of moderate or low risk. Broad panel or genomic tests increase anxiety with increased number of variants of uncertain significance (VUS), increase the risk of misinterpretation or misattribution to less well understood gene or genomic region, and lead to increased costs of unnecessary screening and surgeries.
Sources:
Adams VA, et al. Insights and Considerations for Large Panel Genetic Tests. Informed DNA. 2019 Oct 22.
Lynce F et al. How far do we go with genetic evaluation? Gene, Panel, and Tumour Testing. Am Soc Clin Oncol Educ Book. 2016; 35:e72-e78. PMID: 27249773.
National Academies of Sciences, Engineering, and Medicine et al. An Evidence Framework for Genetic Testing. Washington (DC): National Academies Press (US); 2017 Mar 27. PMID: 28418631.