A Single Base-Pair Deletion in Exon 7 in qgaa1 Gene Responsible for Acid Maltase Deficiency in Japanese Quail (Coturnix Coturnix Japonica)

By sequence analysis in ten quails with acid maltase deficiency (AMD), we have identified the mutation in qgaa1 gene, but not in qgaa2 gene. No mutations were detected in either gaa gene in ten normal quails. AMD quails had a novel G deletion at nucleotide position 1639 in exon 7 in qgaa1 gene (designated 1639delG). This deletion causes a frameshift altering the amino acid sequence from position 366 on and introduces a premature stopcodon at amino acid position 390. A second qgaa2 gene having frequent polymorphisms in the sequence of cDNAs and extremely shorter introns than qgaa1 gene, may account for the low level of serum acid alpha glucosidase (GAA) activity and the reduction of clinical severity in AMD quails.