Identification of Cryptic Novel α-Galactosidase A Gene Mutations: Abnormal mRNA Splicing and Large Deletions
Anderson-Fabry (FD) disease is an inborn error of metabolism caused by a deficiency of α-galactosidase A (GLA), a lysosomal enzyme. Many male FD patients display a classic FD phenotype; however, some female patients have neither reduced leukocyte GLA enzyme activity level nor FD symptoms. Thus, GLA gene analysis is especially important for diagnosing suspected FD in female subjects. In this study, we revealed 4 novel GLA gene mutations in 5 independent families using GLA cDNA analysis and multiplex ligation-dependent probe amplification (MLPA) analysis. These distinct mutations included a large deletion mutation from intron 1 to exon 5 (c.195-471_c.691del5.5k, corresponding to g.8508_g.14069del5.5k), an insertion mutation of splicing enhancer sequence in intron 4 (c.639+329_c.639+330ins113, corresponding to g.12627_g.12628ins113), an insertion mutation of retrotransposon L1 in exon 4 (c.634_c.635, corresponding to g.12293_g.12294), and a non-SNP deep intronic point mutation in intron 3 (c.547+395G>C, corresponding to g.11727G>C). It is difficult to detect these mutations with direct sequencing of only the exonic element. When exonic mutations are not found in the GLA gene from suspected FD patients, GLA cDNA and MLPA analyses should be performed to detect large deletion/insertion and intronic mutations including transcription abnormalities.
KeywordsEnzyme Replacement Therapy Inverted Repeat Sequence Female Family Member cDNA Sequence Analysis Large Deletion Mutation
We thank our colleagues for their excellent technical assistance, Rie Ando (Oita Univ. Fac. of Med.), Miki Itohsa, Sayoko Iizuka, and Asako Morita (Div. of Gene Ther., The Jikei Univ.), and we thank Hidehito Kuroyanagi (Lab. of Gene Expres., Dep. of Func. Genomi., Med. Res. Inst., Tokyo Medical and Dental Univ.) for excellent discussions. We thank the primary medical doctors introducing the patients with FD to The Jikei Univ. hospital.
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