Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect (CHD). TOF may present in isolation or in conjunction with one or more non-cardiac congenital anomalies or neurodevelopmental disorders (TOF+). Uncertainty regarding the efficacy of various genetic testing strategies, and an incomplete understanding of the genetic causes of TOF+, may lead to hesitancy in recommending genetic testing, particularly, clinical exome sequencing (cES). Here, we analyzed cES data from 131 individuals with TOF+. A definitive or probable diagnosis was made for 31 individuals, yielding a diagnostic rate of 23.6% (31/131). One individual received three diagnoses. Commercially available CHD panels would have detected only 27.3% (9/33) to 63.6% (21/33) of the diagnoses made by cES. We then used a machine learning approach to identify four genes for which there is sufficient evidence to support a phenotypic expansion including TOF: DVL3, MED13L, PUF60, and MEIS2. Since chromosomal microarray analysis (CMA) has been reported to have a diagnostic efficacy of 10-20% in individuals with TOF, we conclude that cES should be considered for all individuals with TOF+ for whom a molecular diagnosis has not been established by CMA. We also conclude that TOF represents a low penetrance phenotype associated with genetic syndromes caused by pathogenic variants in DVL3, MED13L, PUF60, and MEIS2.
Volpi et al. (Tue,) studied this question.