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目的 检测、分析编码基底膜Ⅳ型胶原α5链基因COL4A5突变及其特点 ,正确理解α5 (Ⅳ )链免疫荧光学检查结果及意义。方法 报告 1例 7岁男性患儿 ,血尿半年 ,肾功能、听力及眼部检查均正常 ;肾脏病理电镜示基底膜大部分均匀变薄 ;有血尿、肾功能不全家族史。应用间接免疫荧光学方法检测该患儿肾脏基底膜α3(Ⅳ )、α4 (Ⅳ )和α5 (Ⅳ )链以及皮肤基底膜α5 (Ⅳ )链。应用逆转录 聚合酶链反应和直接测序的方法分析α5 (Ⅳ )链mR NA ,应用PCR和直接测序方法分析COL4A5基因。结果 患儿肾小球基底膜α3(Ⅳ )、α4 (Ⅳ )和α5 (Ⅳ )链以及皮肤基底膜α5 (Ⅳ )链染色均正常。mRNA和基因组DNA分析均证实碱基替代突变 (917G >A) ,导致α5链第 2 39位甘氨酸被精氨酸取代 ,为新发现的突变。结论 首次报道了皮肤和肾小球基底膜α5 (Ⅳ )链染色正常 (阳性 )的我国X连锁型Alport综合征男性患者COL4A5基因突变及特点。提示应正确应用和理解基底膜α5 (Ⅳ )链免疫荧光学检查结果 ,X连锁型Alport综合征男性患者皮肤和肾小球基底膜α5 (Ⅳ )链染色即便正常 (阳性 ) ,当家族史及其它临床资料仍怀疑Alport综合征时 ,应进行COL4A5基因的检测和分析。
Objective To detect and analyze the mutation of COL4A5, which encodes α5 chain gene of collagen Ⅳ, and to understand correctly the results and significance of α5 (Ⅳ) chain immunofluorescence. Methods A 7-year-old male with hematuria was reported for six months. Renal function, hearing and eye examination were normal. Most of the basement membrane of the renal pathology showed thinning, with a family history of hematuria and renal insufficiency. The expression of α3 (Ⅳ), α4 (Ⅳ) and α5 (Ⅳ) chains in the kidney and the α5 (Ⅳ) chain of the skin basement membrane were detected by indirect immunofluorescence staining. The α5 (Ⅳ) chain mR NA was analyzed by reverse transcription polymerase chain reaction (RT - PCR) and direct sequencing. The COL4A5 gene was analyzed by PCR and direct sequencing. Results The glomerular basement membrane α3 (Ⅳ), α4 (Ⅳ) and α5 (Ⅳ) chains and the skin basement membrane α5 (Ⅳ) chain staining were normal. mRNA and genomic DNA analysis confirmed that the base substitution mutation (917G> A), resulting in the α5 chain of glycine substitution of 39th arginine, is a newly discovered mutation. Conclusions The COL4A5 gene mutation in male X-linked Alport syndrome patients with normal (positive) skin and glomerular basement membrane α5 (Ⅳ) chains was first reported. It is suggested that the results of immunofluorescence assay of basal lamina α5 (Ⅳ) chain should be applied and understood correctly. Even if the positive (positive) staining of the skin and glomerular basement membrane α5 (Ⅳ) chain in X-linked Alport syndrome patients, Other clinical data is still suspected Alport syndrome, COL4A5 gene should be detected and analyzed.