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黏多糖贮积症Ⅱ型(MPSⅡ)具有高度遗传异质性.应用PCR-DNA测序等方法对中国MPSⅡ家系的IDS基因的突变热点进行研究,发现1467-A新突变.该突变位于exon9编码区内第448位的密码子,即cDNA第1467bp的腺嘌呤(A)后缺了1个A.这一移码突变使得新序列在第460位提前遇上终止密码TGA,导致氨基酸从正常的550个减至459个,这一变异引起IDS酶蛋白一级结构和三级立体结构发生显著改变,导致IDS酶活性严重降低.推测此突变可能是引起本病的直接原因,为产前基因诊断创造了必要的前提条件.
MPSⅡhad a high degree of hereditary heterogeneity.The mutation hot spot of IDS gene in Chinese MPSⅡ pedigree was studied by PCR-DNA sequencing and a new 1467-A mutation was found in the exon9 coding region The 448th codon, ie, the 1467th bp adenine (A) of cDNA, is absent by 1 A. This frameshift mutation led to the new sequence ending at position 460 ahead of the stop codon TGA, resulting in a shift of amino acids from the normal 550 A decrease to 459, this mutation caused a significant change in primary structure and tertiary structure of IDS enzyme, resulting in a serious decline in IDS activity.It is speculated that this mutation may be the direct cause of the disease, for prenatal genetic diagnosis to create The necessary prerequisites.