BCR/ABL1 transcripts, the molecular hallmarks of chronic myeloid leukemia (CML), have been detected in peripheral blood from healthy individuals. Although CML is a sporadic disease, familial occurrence has been reported. This raises the question of whether there is a hereditary factor related to the etiology of CML. Our aim is to compare the BCR/ABL1 e13a2 and e14a2 transcript frequency in healthy first-degree relatives of families with CML versus individuals from families without CML antecedents. Ninety-eight healthy individuals, sorted into two groups, were studied: a group consisting of 46 first-degree relatives from families having a CML affected, and another with 52 healthy individuals from families without CML antecedents. BCR/ABL1 e13a2 and e14a2 transcripts were detected in mRNA isolated from peripheral blood leukocytes. We observed 28 of 98 individuals positive for at least one BCR/ABL1 transcript: e14a2 was detected in 22, e13a2 in 4, and co-expression was observed in 2 subjects. The positivity rate in relatives of CML cases was 33%, whereas individuals without CML antecedents had a 25% positivity rate, showing no statistical difference. Our results corroborate the presence of e13a2 and e14a2 BCR/ABL1 transcripts in the peripheral blood of healthy individuals, but has not a found familial factor related to the etiology of this rearrangement.© 2019 by the Association of Clinical Scientists, Inc.