Identification of a novel mutation in the amelogenesis-related genes in Japanese families affected with amelogenesis imperfecta and an approach toward gene therapy

无釉发育不全症（AI）是一类以牙釉质形成缺陷为特征的异质性遗传疾病。1)我们对一个可能存在常染色体显性Al的日本家庭进行了分子遗传学研究，发现了釉素基因的一个新的突变。在受影响的兄弟和他们的父亲身上检测到的突变是在搪瓷蛋白基因外显子9-intion 9边界的一系列7G残基内的杂合单g缺失。在其他未受影响的家族成员或对照个体中未检测到釉素基因突变，这表明釉素基因突变是导致ai常染色体显性发育不全的原因。2)我们研究了一个日本家庭，该家庭表现出牙齿形成的遗传异常，其特征是牙齿具有垂直凹槽（女性）和小棕色牙齿（男性），并发现位于X染色体p22.1-22.3区域的釉素基因突变。突变分析显示，在淀粉原蛋白基因的第5外显子C到G点突变，该突变将精氨酸取代脯氨酸^<52>。这种替换与患病家族成员的牙齿异常共分离，编码脯氨酸^<52>的位点在其他哺乳动物中高度保守。这一结果表明，在这个日本家族中检测到的突变是导致x连锁ai的原因。3)我们还测试了一种新的逆转录病毒载体gcapm - ada在造血细胞中转导基因的能力，发现这种方法对患者有益。4)研究巨噬细胞迁移抑制因子（macrophage migration inhibitory factor， MIF）对破骨细胞形成的调控作用，发现MIF通过阻止多核过程抑制成熟破骨细胞的形成。

Amelogenesis imperfecta (AI) is a heterogeneous group of genetic disorders characterized by the defects of tooth enamel formation.1) We performed molecular genetic studies for a Japanese family with a possible autosomal dominant form of Al, and found a novel mutation in the enamelin gene. The mutation detected in the affected brothers and their father was a heterozygous single-G deletion within a series of 7G residues at the exon 9-intion 9 boundary of the enamelin gene. The enamelin gene mutation was not detected in other unaffected family members or control individuals suggesting that the mutation in the enamelin gene is responsible for an autosomal dominant hypoplastic form of AI.2) We studied a Japanese family that exhibits inherited abnormality in tooth formation characterized by teeth with vertical grooves (female) and small brownish teeth (male), and found a mutation in the amelogenin gene located in the p22.1-22.3 region of the X chromosome. Mutation analysis revealed a C to G point mutation in exon 5 of the amelogenin gene, which would substitute arginine for proline^<52>. This substitution co-segregated with the tooth abnormality in the affected family members and the locus encoding proline^<52> highly conserved in other mammals. This result indicates that the mutation detected in this Japanese family is responsible for the X-linked AI.3) We also tested a novel retroviral vector GcsapM-ADA for its ability to transduce genes in hematopoietic cells and found this method to be beneficial to patients.4) The regulatory effects of the macrophage migration inhibitory factor (MIF) on osteoclast formation were examined and we found that MIF inhibits formation of mature osteoclasts by preventing the multinucleation process.