Molecular characterization of hemophilia B patients in Colombia

BACKGROUND: Hemophilia B (HB) is a coagulation disorder with an X‐linked recessive inheritance pattern, caused by plasma FIX deficiency. In Colombia, HB is considered a rare and high‐cost disease, with 362 males reported in 2017. METHODS: Here, we characterized 20 HB apparently unrelated families by PCR amplification and Sanger sequencing. RESULTS: Fourteen unique variants were identified: seven missense, three nonsense, one variant in the 3′ UTR region, two large deletions >50 bp, and one intronic substitution that affects splicing c.520+13A>G that was present in 7/20 patients (35%). All these variants have been previously reported in the literature, except for exons 3 and 4, deletions, present in one patient. The genotype‐phenotype association correlates with the reported in the literature, with the exception of one patient. CONCLUSION: This molecular analysis allowed us to establish the causal variant of HB in 100% of patients, to provide the appropriate genetic counseling to each of the families, and to propose a more cost‐effective carrier analysis. Here, we reported the first variants in Colombian population with Hemophilia B, finding a new variant and one intron recurrent variant present in 35% of patients.