Cryptic splicing due to a point mutation in IVS 11.

(A) Sequence of ADA cDNA clone derived from B LCL of Sib A, showing a 13-nt insert at the exon 11/12 junction (underlined). The insert corresponds to g.31703-31715, normally the last 13 nt of IVS 11. The TGA stop codon (underlined) and the start of the 3′ untranslated region (3′UTR, arrow) are indicated. (B) Partial sequences of fragment g.31016-31920 (IVS 10-exon 12) amplified from uncloned DNA from buccal brushings of patients, as indicated. The sequence g.31694-31704 is shown. Asterisks indicate an A at nt g.31701 in all 4 patients, instead of T found in wild-type (WT) human ADA.