Southern blot analysis of the 3′ endpoint genomic deletion. (A) Southern blot analysis of genomic DNA from control (C) and proposita (I.2), using pA2.1 cDNA probe (see also Fig 1). Restriction enzymes used are indicated. Band sizes (in kilobases) are given. Underlined sizes correspond to half intensity bands; *abnormal bands; •polymorphic site c.24 (B) Partial restriction map, around exon 13, of normal 4.1 gene (top) and shortened allele 4.1 Annecy (bottom). X, B, M, and E represent restriction sites ofXba I, Bgl II, Msp I, and EcoRI enzymes, respectively. Underlined sites had been previously localized (Baklouti et al23 and unpublished data). Localization of Msp I site on the normal gene stemmed from results shown on (A). *Msp I site originating from intron 1 region. (░) The approximately 1-kb region containing the 3′ endpoint of the genomic deletion.