Figure 2-6927.

DNA sequences of GJB2. A heterozygous A to T transition at codon 40 is detected in the patient’s gene (NM_004004:c.40A>T). This mutation leads to the amino acid substitution N14Y. This missense mutation is de novo because it is not found in the parent’s DNA. N14Y results in the gain of a Bsp1407I restriction site. PCR products from the patient (Pt) are digested into fragments of 733 and 943 bp. In contrast, the digested PCR products from the father (Fa) show only the 943-bp band.