Not Only Diagnostic Yield: Whole-Exome Sequencing in Infantile Cardiomyopathies Impacts on Clinical and Family Management.

Whole-exome sequencing (WES) is a powerful and comprehensive tool for the genetic diagnosis of rare diseases, but few reports describe its timely application and clinical impact on infantile cardiomyopathies (CM). We conducted a retrospective analysis of patients with infantile CMs who had trio (proband and parents)-WES to determine whether results contributed to clinical management in urgent and non-urgent settings. Twenty-nine out of 42 enrolled patients (69.0%) received a definitive molecular diagnosis. The mean time-to-diagnosis was 9.7 days in urgent settings, and 17 out of 24 patients (70.8%) obtained an etiological classification. In non-urgent settings, the mean time-to-diagnosis was 225 days, and 12 out of 18 patients (66.7%) had a molecular diagnosis. In 37 out of 42 patients (88.1%), the genetic findings contributed to clinical management, including heart transplantation, palliative care, or medical treatment, independent of the patient's critical condition. All 29 patients and families with a definitive diagnosis received specific counseling about recurrence risk, and in seven (24.1%) cases, the result facilitated diagnosis in parents or siblings. In conclusion, genetic diagnosis significantly contributes to patients' clinical and family management, and trio-WES should be performed promptly to be an essential part of care in infantile cardiomyopathy, maximizing its clinical utility.

Double homozygosity in CEP57 and DYNC2H1 genes detected by WES: Composite or expanded phenotype?

BACKGROUND: In the last few years trio-whole exome sequencing (WES) analysis has demonstrated its potential in obtaining genetic diagnoses even in nonspecific clinical pictures and in atypical presentations of known diseases. Moreover WES allows the detection of variants in multiple genes causing different genetic conditions in a single patient, in about 5% of cases. The resulting phenotype may be clinically discerned as variability in the expression of a known phenotype, or as a new unreported syndromic condition. METHODS: Trio-WES was performed on a 4-month-old baby with a complex clinical presentation characterized by skeletal anomalies, congenital heart malformation, congenital hypothyroidism, generalized venous and arterial hypoplasia, and recurrent infections. RESULTS: WES detected two different homozygous variants, one in CEP57, the gene responsible for mosaic variegated aneuploidy syndrome 2, the other in DYNC2H1, the main gene associated with short-rib thoracic dysplasia. CONCLUSION: The contribution of these two different genetic causes in determining the phenotype of our patient is discussed, including some clinical signs not explained by the detected variants. The report then highlights the role of WES in providing complete and fast diagnosis in patients with complex presentations of rare genetic syndromes, with important implications in the assessment of recurrence risk.

Atypical presentation of pediatric BRAF RASopathy with acute encephalopathy.

We report a 9-year-old girl with hypotonia, severe motor delay, absent speech, and facial dysmorphism who developed acute encephalopathy with severe neurological outcome. Trio-based whole exome sequencing (WES) analysis detected a de novo heterozygous mutation in the BRAF gene leading to the diagnosis of an atypical presentation of cardiofaciocutaneous (CFC) syndrome. This is the second case of CFC syndrome complicated with acute encephalopathy reported in the literature and supports the hypothesis that acute encephalopathy might be one of the complications of the syndrome due to an intrinsic susceptibility to this acute event. The report furthermore highlights the role of WES in providing a fast diagnosis in patients in critical conditions with atypical presentation of rare genetic syndromes.