Analysis of SNP3 (C598T) in patient and control samples. (A) Sequence results of the C598T patient and his mother. At nucleotide number 598, the patient has a C and T, indicated by N. The patient's unaffected mother is homozygous for C. (B) Pvu II site amplified with 3F and 3R. The size of PCR product amplified with 3F and 3R is 790 bp and contains three Pvu II restriction sites. When the PCR product from a control subject is digested with Pvu II, four products of 321 bp, two of 138 bp and two of 10 bp are generated. Since the C598T removes the first Pvu II restriction site, digestion of the amplification product will produce a fragment of 459 bp instead of 321 bp and 138 bp. (C) Electrophoresis of PCR product digested with Pvu II shows that the patient and his unaffected father both have a band of 459 bp. The 138 bp fragment in the mother and control is twice as strong as those of the patient and the father. Similarly the 321 bp band in the mother and control is stronger than in the patient and his father.