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外祖父的体细胞嵌合,很好地解释了一个家族的Duchenne型肌营养不良的携带状态和产前诊断结果。用基因内DNA多态分离分析,血清肌酸磷酸激酶测定,和患者的体格检查,可辨认出这种遗传状况。在携带者和产前诊断上,DMD位点的这种变化代表一个更潜在的错误原因。 Duchenne型肌营养不良是X连锁隐性疾病,大约1/3 300男性受累,其中1/3男性表现为新的突变。DMD基因定位在Xp21带上,编码肌营养不良基因产物。这种产物异常或缺失时,肌酸包括肌酸磷酸激酶逸入到血清中。在诊断有发病风险妇女时,CPK水平低并不表示不是携带者,因为正常妇女和携带者间酶活性有重叠。
Somatic cell chimerism of the grandfather is a good explanation of the status of a Duchenne muscular dystrophy and the prenatal diagnosis of a family. This genetic condition can be identified by genetic polymorphism in the DNA, serum creatine kinase assay, and physical examination of the patient. This change in DMD loci represents a more potential cause of error in carriers and prenatal diagnosis. Duchenne muscular dystrophy is an X-linked recessive disease affecting approximately 1/3 300 males, of whom 1/3 males exhibit new mutations. The DMD gene is located on the Xp21 band and encodes the muscular dystrophy gene product. Creatine, including creatine phosphokinase, escapes into the serum when this product is abnormal or absent. In diagnosing women at risk, low CPK does not mean that they are not carriers because there is overlap in enzyme activity between normal women and carriers.