Nonsense mutation (Q1828X) identified in family PK031. A. MRF-SSCP analysis in SI 4 fragment from the patient of family PK031. The restriction maps of Bgl I + Hha I and Ava II digestions of SI 4 fragment (upper). The dotted square area indicates the region with mobility shifts in the MRF-SSCP analysis of SI 4 fragment from the patient. The SSCP patterns (lower) of SI 4 fragment digested with Bgl I + Hha I (left) and Ava II (right) show mobility shifts of single-stranded DNAs (pointed) in the patient's sample (P) compared with that of normal control (N). Double-stranded DNA fragment-size markers (ds) were included for each set. The mobility shifts were observed in the fragments with the sizes of 476 bp in the first set and 253 bp in the second one. The two fragments were located in the same region within the positions 5670–5911. B. Direct sequencing analysis of PKD1 -cDNA from the patient of family PK031. The sequencing profile shows a nucleotide substitution (c.5693C>T), resulting in a nonsense mutation; CAG (glutamine) was changed to TAG (stop) at codon 1828 (Q1828X).C. Restriction map of RFLP analysis for g.29591C>T (Q1828X) in PKD1 -genomic DNA. Four DNA fragments with the sizes of 117, 134, 91 and 30 bp are obtained from the normal allele, whereas only 3 fragments with the sizes of 251, 91 and 30 bp are generated from the mutant allele carrying the g.29591C>T mutation because of the loss of a Pvu II recognition site at the position 29593. D. Results of direct detection for g.29591C>T (or Q1828X) mutation by Pvu II digestion in members of the family PK031. The appearance of 251-bp fragment in I-1, II-1, and II-2 indicates the presence of Q1828X mutation. The mother (I-2) did not have the 251-bp fragment; thus, she did not carry the mutation. N is normal control sample digested with the same enzyme.