Mutation analysis and gene expression. a, Sequence analysis revealed a homozygous G deletion at SNAP29 cDNA position 220 in all affected individuals of both families (upper panel). All obligatory carriers were shown to carry the mutation in a heterozygous state (middle panel). The wild-type sequence is given for comparison (lower panel). b, The corresponding dHPLC tracings obtained by running PCR samples unmixed and mixed with control DNA are depicted. c, Expression of SNAP29 and ACTB, coding for β-actin, assessed using RT-PCR in fibroblasts harvested from a patient (P) and from a healthy control individual (C). Note the lower amounts of the SNAP29 RT-PCR products in the patient relative to the control. d, Quantitative real-time PCR analysis for gene expression of SNAP29 in fibroblasts obtained from control and patient skin. Expression levels are expressed as absolute values normalized relative to β-actin RNA levels.