Structural and immunocytochemical studies on a-N-acetylgalactosaminidase deficiency (Schindler/Kanzaki disease)
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- 作者：Hitoshi Sakuraba ; Fumiko Matsuzawa ; Sei-ichi Aikawa ; Hirofumi Doi ; Masaharu Kotani ; Hiroshi Nakada ; Tomoko Fukushige and Tamotsu Kanzaki
- 关键词：N ; acetylgalactosaminidase deficiency ; Schindler disease ; Kanzaki disease ; Homology modeling ; Tn ; antigen
- 刊名：Journal of Human Genetics
- 出版年：2004
- 出版时间：January 2004
- 年：2004
- 卷：49
- 期：1
- 页码：1-8
- 全文大小：2,195 KB
文摘
-N-Acetylgalactosaminidase (-NAGA) deficiency (Schindler/Kanzaki disease) is a clinically and pathologically heterogeneous genetic disease with a wide spectrum including an early onset neuroaxonal dystrophy (Schindler disease) and late onset angiokeratoma corporis diffusum (Kanzaki disease). In -NAGA deficiency, there are discrepancies between the genotype and phenotype, and also between urinary excretion products (sialyl glycoconjugates) and a theoretical accumulated material (Tn-antigen; Gal NAc1--Ser/Thr) resulting from a defect in -NAGA. As for the former issue, previously reported genetic, biochemical and pathological data raise the question whether or not E325K mutation found in Schindler disease patients really leads to the severe phenotype of -NAGA deficiency. The latter issue leads to the question of whether -NAGA deficiency is associated with the basic pathogenesis of this disease. To clarify the pathogenesis of this disease, we performed structural and immunocytochemical studies. The structure of human -NAGA deduced on homology modeling is composed of two domains, domain I, including the active site, and domain II. R329W/Q, identified in patients with Kanzaki disease have been deduced to cause drastic changes at the interface between domains I and II. The structural change caused by E325K found in patients with Schindler disease is localized on the N-terminal side of the tenth -strand in domain II and is smaller than those caused by R329W/Q. Immunocytochemical analysis revealed that the main lysosomal accumulated material in cultured fibroblasts from patients with Kanzaki disease is Tn-antigen. These data suggest that a prototype of -NAGA deficiency in Kanzaki disease and factors other than the defect of -NAGA may contribute to severe neurological disorders, and Kanzaki disease is thought to be caused by a single enzyme deficiency.