We employed the diepoxybutane (DEB) test for FA diagnosis, arrayCGH for detection of duplication, targeted capture and next‐gen sequencing for defining the duplication breakpoint, PacBio sequencing of full‐length FANCB aberrant transcript, FANCD2 ubiquitination and foci formation assays for the evaluation of FANCB protein function by viral transduction of FANCB‐null cells with lentiviral FANCBWT and mutant expression constructs, and droplet digital PCR for quantitation of the duplication in the genomic DNA and cDNA. The gene discussed is FANCD2; the disease is Friedreich ataxia.