DELETION OF EXON-18 IS A FREQUENT MUTATION IN GLYCOGEN-STORAGE-DISEASE TYPE-II

An abnormal 2.3 kb SacI fragment of the human lysosomal alpha-glucosid ase gene (GAA) was identified in patients with glycogen storage diseas e type II. The fragment results from deletion of exon 18 and adjacent parts of intron 17 and 18. The borders of the deletion are marked by t he occurrence of an eight nucleotide long tandem repeat (AGGGGCCG) whi ch is apparently instrumental in the mutation event. The exon 18 delet ion was demonstrated in 10 out of 39 patients from Europe (all hetero- allelic) and is so far the most common mutation in this disease (allel e frequency among patients is 0.13). (C) 1994 Academic Press, Inc.