SMN1 copy number analysis for the family of Case 3. 1A The pedigree of the family of Case 3. 1B: Exon 7 PCR-RFLP Polyacrylamide gels showing the undigested and digested products of SMN exon 7 after Dra I digestion. Lane 1, undigested product of patient; Lane 2, digested product of patient with SMN1 deletion; Lane 3, undigested product of sibling; Lane 4, digested product of sibling with no SMN1 deletion. 1C: Exon 8 PCR-RFLP after Dde I digestion. Lanes 1 and 3, undigested PCR product; Lane 2, digested product of patient with homozygous deletion of exon 8 of the SMN1 gene; Lane 4, digested product of sibling with no homozygous deletion of SMN1. 1D Quantitative PCR gel scans of Father (I: 1), Mother (I: 2) and sibling (II: 4). Band sizes in base pairs are shown in the upper boxes and peak areas in the lower boxes. IS, internal standards.