Studies on the genetic analysis of a patient with protein C deficien

我们报告了一例患新生儿暴发性紫癜性紫疹的男婴的蛋白C基因遗传异常。对该家系蛋白C基因所有cxon进行序列分析，发现两个突变。第一个突变来自母亲，是外显子IX 10758位核苷酸的四个连接G中的一个缺失，导致C蛋白羧基末端的氨基酸序列从Gly381到Gly381的微小改变；第二个异常来自父亲，是外显子III的第2977个核苷酸从G突变为A，这将导致用Lys取代伽玛-羧谷氨酸(Gla)26。这一变化将导致患者和父亲的免疫蛋白C水平下降，通过一种以钙依赖的方式识别GLA结构域的单抗估计(分别为3.8%和57%)。从父亲的血浆中部分纯化的异常蛋白C显示出正常的氨解活性和电泳率的变化。我们用两种方法检测了他的家族成员的上述突变，一种是利用诱变引物创建新的限制性内切酶切点，另一种是单核苷酸引物延伸。这两种方法对产前蛋白C异常的诊断都是快速有效的。

We report genetic abnormalities of protein C gene in a male infant who developed neonatal purpura fulminans. DNA-sequence analysis of all cxons in protein C gene in this family revealed two mutations the first abnormality, derived from the mother, was a deletion of one of four consccutive g at nucleotide number 10758 in exon IX which would result in a frame shift mutation and com ; letely change amino acid sequence from Gly381 in the carboxyl-terminal region of protein C.The second abnormality, derived from the father, was a single nucleotide mutation from G to A in the codon (GAG to AAG) at nucleotide number 2977 in exon III, which would result in a substitution of Lys for gamma-carboxyglutamic acid (Gla) 26. This change would be responsible for the reduced immunological protein C levels of the patient and the father, estimated by a monoclonal antibody which recognizes the Gla-domain in a Ca^<2+>-dependent manner (3.8% and 57%, respectively). Partially purified abnormal protein C from the father's plasma showed a normal amidolytic activity and a change in the electrophoretic mobility. We detected the above mutations in his family members using two methods ; one was a creation of new restriction enzyme sites using mutagenic primers and the other was single nucleotide primer extension. Both methods are rapid and useful for the diagnosis of prenatal protein C abnormalities.