Identification of an 8.4-kb deletion upstream of MCFD2. (A) Schematic representation of the genomic region containing MCFD2 on human chromosome 2 (negative strand). Sac I and HindIII restriction sites are indicated by ↑, PCR oligonucleotide primers (not to scale) used to amplify and sequence the deleted allele are indicated by →←. The probe used for Southern blotting is shown as a black box. *The deletion eliminates 8.4 kb of DNA including exon 1 but retains 2 small sequences of 55 bp (in the 5′ genomic region, approximately 3.4 kb upstream of exon 1) and 96 bp (starting 9 bp inside intron 1) in inverted orientation. (B) Southern blot analysis with Sac I and HindIII. An image of the gel electrophoresis is shown to the left of each Southern blot, the patient's DNA sample (P) migrates more slowly than the samples from the controls (C) and from the patient's mother (M) so that the patient's normal band in both blots appears to be of greater size.