第一型黏多醣儲積症 (MPS I) 是因溶小體酵素 a-L-iduronidase (IDUA) 活性缺失或大量降低，所導致的體染色體隱性遺傳疾病。由於患者體內酸性黏多醣廣泛的儲積，影響到人體多處組織、器官的正常功能。IDUA基因位於第四號染色體的短臂 (4p16.3)，並已被選殖及定序。在目前對MPS I 患者的基因突變分析中，已發現近五十種的突變及三十種的多型性，顯示出IDUA 基因突變的高度異質性及多型性變化。 本論文的目的在探討台灣 MPS I 患者的分子致因，並藉多型性分析，以了解 IDUA 基因上各多型性點的連鎖不平衡關係。在突變分析方面，利用聚合酵素鏈反應-單股核酸構形多型性 (PCR-SSCP) 的技術初步篩選可能帶有突變的表現子，其次，對於SSCP 構形異常的表現子加以選殖及定序分析。結果發現患者 766 為 R619G 的同型合子突變，即 IDUA cDNA 第 1943 個核甘酸發生C * G的巔換，使第619 個胺基酸由鹼性的精胺酸Arg (CGA) 轉變成中性的甘胺酸Gly (GGA)。進一步構築含 R619G 變異的IDUA cDNA重組質體，經lipofection的方式轉染COS-7細胞中表現，並測定野生型及突變型重組質體轉染細胞株所表現的IDUA酵素活性，發現含 R619G 變異的 IDUA 酵素活性僅為野生型的 3.6 % 。以北方吸漬法分析重組質體細胞株的mRNA 表現量，發現 R619G變異並未對 IDUA mRNA 之穩定性造成顯著影響。此外，對偶基因專一性的寡核甘酸引子 (ASO) 及藉由mismatch primer 引入限制酵素切割點的RFLP分析顯示，患者的父母皆為此突變基因的攜帶者。 於患者 770、771 兩姐妹的突變分析中，SSCP 及 DNA 定序並未發現任何變異存在，於多型性單套型的分析中卻發現兩姐妹分別遺傳了來自父母親不同的染色體，且患者白血球中之IDUA 酵素活性亦與正常人相近。後經其它研究者檢測，確定此二姐妹為MPS VI 患者。

a-L-Iduronidase (IDUA) is one of the lysosomal enzymes involved in degradation of glycoaminoglycans. Loss or marked reduction of IDUA activity results in the autosomal recessive mucopolysaccharidosis type I (MPS I). Many tissues and organs are affected due to the storage of glycoaminoglycans. The IDUA gene was mapped on chromosome 4p16.3 and the sequence determined. Mutation screening in patients with MPS I have identified nearly 50 different mutations underlying the disorder. In addition, nearly 30 polymorphisms and/or nonpathogenic sequence variants have been detected. These studies demonstrated the heterogeneity and polymorphism occurred in the IDUA gene. The purpose of this study was to investigate the molecular lesion of MPS I patients and to analyse the linkage disequilibrum in the IDUA gene. In mutational analysis, the coding sequence and exonntron borders of the IDUA gene were amplified by polymerase chain reaction (PCR) and subjected to single-strand conformation polymorphism (SSCP) analysis. The aberrant SSCP conformers were cloned and sequenced.The results demonstrated that patient 766 is homozygous for mutation R619G (C→G transversion in codon 619). By PCR-restriction fragment length polymorphism (RFLP) and allelle specific oligonucleotide (ASO) hybridization analyses, the heterozygous mutation was detected in both parents. Expression of R619G showed the reduction (3.6 %) of IDUA activity compare to that of wild type IDUA cDNA upon transfection into COS-7 cell,despite there is no difference in mRNA levels. In analysis of patients 770 and 771, SSCP and DNA sequencing failed to reveal any variations. The results from haplotype analysis suggested that the two patients inherited different allelles from both parents. The patient's leukocyte IDUA activities were in the normal range. The patients were confirmed to be MPS type VI, after further analysis by collaborators . In mutational analysis of patient 1413, an aberrant Q33H RFLP fragment was detected. After cloning and sequencing , a 12 nucleotides in frame deletion in exon 1 (134del12) was identified. The134del12 was maternally inherited. The mutation inherited from the father has not yet to be identified. The polymorphic DNA haplotype of the IDUA gene in Chinese subjects was also investigated in this study. Genomic DNA from 72 randomly-sampled normal individuals was used to amplify DNA fragments containing the polymorphic site BstXI (intron2), Msp I (intron5), and AluI (intron10). The PCR amplified products were analyzed by RFLP. Among seventy-two individuals examined , no BstXI polymorphic allele was observed. The MspI (intron5) and AluI (intron10) polymorphisms were in Hardy-Weinberg equilibrium. The allele frequeny of MspI and AluI (20 %) and heterozygosity (35 %) were identical with one another. In fact, identical polymorphic gennotype of MspI and AluI was observed for each individual tested. The results suggest strong nonrandom association between MspI and AluI loci. Similar strong nonrandom association among R105Q, MspI and AluI was also found.