Characterization of a novel BRCA1 splice site variant (c.560 + 2 T > A) in one HBOC patient. A: Sequencing pattern of BRCA1 exon 7 from blood cell genomic DNA showing the c.560 + 2 T > A mutation. B: Agarose gel showing RT-PCR products obtained from the cDNA of a tumor from patient MO-15 and one control sample (sporadic tumor negative for the c.560 + 2 T > A) using a forward primer in exon 6 and a reverse primer in exon 8 of BRCA1. An additional 186-bp cDNA fragment caused by the partial deletion of exon 7 was observed in the tumor sample of patient MO-15. C: Above, partial sequence of the expected fragment (258 bp) in the control tumor sample showing the exon 7–8 junction; below, partial sequence of the patient tumor cDNA showing the creation of a novel cryptic splice donor site causing the deletion of the last 62 bp of BRCA1 exon 7 in the aberrant transcript. D: Schematic representation of the premature stop codon (p.Ser127Thrfs*11) created in the BRCA1 mRNA after the frameshift deletion of the last 62 bp of exon 7 caused by the germ line splice site variant c.560 + 2 T > A. E: Amino acid sequence of the expected truncated protein (137 aa) showing the alteration of 10 amino acids (in red) and creation of a premature stop codon (*).