Fig. 4
From: Perspectives and diagnostic considerations in spinal muscular atrophy
SMN1 dosage analysis of a normal control and two SMA carriers. The SMN1/CF ratio for the carrier is half the ratio of the normal control. The quantitative PCR assay uses an exon of the cystic fibrosis (CF) gene as a standard to determine the copy number of the SMN1 and SMN2 genes. The assay also incorporates the use of two internal standards (IS-CF and IS-SMN) to monitor the efficiency of the PCR reaction and to ensure that equal amounts of target genomic DNA are added to each tube. A, normal control with two SMN1 copies and two SMN2 copies. B, SMA carrier with one SMN1 copy and two SMN2 copies. C, SMA carrier with one SMN1 copy and one SMN2 copy.
