Mutation Pro17Ser of the DSPP gene co-segregated with type II DGI in the family. N, normal phenotype; P, affected phenotype; marker, molecular size standard. The lanes are labelled with the unique identification number for each individual in the Chinese family as in Fig. 1. The g.49C>T/Pro17Ser mutation disrupts a BsrI restriction site. The wild type PCR product can be cut by BsrI, yielding two DNA fragments of 268 bp and 200 bp. The PCR fragment containing mutation Pro17Ser cannot be cut by the enzyme, resulting in only one DNA fragment of 468 bp. All affected individuals in the family are heterozygous for the Pro17Ser mutation (three fragments: 468 bp, 268 bp and 200 bp). Normal family members display two 268 bp and 200 bp bands.