Diagnostic yield of chromosomal microarray in the largest Latino clinical cohort.

Copy number variants (CNVs) remain a major etiological cause of neurodevelopmental delay and congenital malformations. Chromosomal microarray analysis (CMA) represents the gold standard for CNVs molecular characterization. We applied CMA throughout the patient's clinical diagnostic workup, as the patient's medical provider requested. We collected CMA results of 3380 patients enrolled for 5 years (2016-2021). We found 830 CNVs in 719 patients with potential clinical significance, that is, (i) pathogenic, (ii) likely pathogenic, and (iii) variants of uncertain significance (VUS), from which 10.6% (predominantly involving chromosomes 15 and 22) were most likely the final cause underpinning the patients' clinical phenotype. For those associated with neurodevelopmental phenotypes, the rate of pathogenic or likely pathogenic findings among the patients with CNVs was 60.75%. When considering epileptic phenotypes, it was 59%. Interestingly, our protocol identified two gains harbored in 17q21.31 and 9q34.3, internationally classified initially as VUS. However, because of their high frequency, we propose that these two VUS be reclassified as likely benign in this widely heterogeneous phenotypic population. These results support the diagnostic yield efficiency of CMA in characterizing CNVs to define the final molecular cause of genetic diseases in this cohort of Colombian patients, the most significant sample of patients from a Latino population, and define new benign polymorphic CNVs.

Advancing Cancer Care in Colombia: Results of the First In Situ Implementation of Comprehensive Genomic Profiling.

BACKGROUND: Comprehensive genomic profiling (CGP) identifies genetic alterations and patterns that are crucial for therapy selection and precise treatment development. In Colombia, limited access to CGP tests underscores the necessity of documenting the prevalence of treatable genetic alterations. This study aimed to describe the somatic genetic profile of specific cancer types in Colombian patients and assess its impact on treatment selection. METHODS: A retrospective cohort study was conducted at Clínica Colsanitas S.A. from March 2023 to June 2024. Sequencing was performed on the NextSeq2000 platform with the TruSight Oncology 500 (TSO500) assay, which simultaneously evaluates 523 genes for DNA analysis and 55 for RNA; additionally, analyses were performed with the SOPHiA DDM software. The tumor mutational burden (TMB), microsatellite instability (MSI), and programmed cell death ligand 1 (PDL1) were assessed. RESULTS: Among 111 patients, 103 were evaluated, with gastrointestinal (27.93%), respiratory (13.51%), and central nervous system cancers (10.81%) being the most prevalent. TP53 (37%), KMT2C (28%), and KRAS (21%) were frequent mutations. Actionable findings were detected in 76.7% of cases, notably in digestive (20 patients) and lung cancers (8 patients). MSI was stable at 82.52% and high at 2.91%, whilst TMB was predominantly low (91.26%). CONCLUSIONS: The test has facilitated access to targeted therapies, improving clinical outcomes in Colombian patients. This profiling test is expected to increase opportunities for personalized medicine in Colombia.