医学遗传学——染色体分组、核型与显带.pptx

1、第二节 染色体分组、核型与显带,Section two Chromosome grouping, karyotype and banding,1960年在美国丹佛(Denver)第一届国际细胞遗传学会议确定人类染色体分组按染色体大小递减次序和着丝粒位置划分Denver体制,110页,一、染色体分组(Chromosome grouping),1-22号常染色体和X、Y性染色体形成24个基因连锁群(linkage group),女性：46，XX,男性：46，XY,二、染色体非显带核型,（The karyotype of non-banding chromosome）,非显带核型分析(karyoty

2、pe analysis),三、染色体显带(chromosome banding),Q显带(Q banding) G显带(G banding) R显带(R banding) T显带(T banding) C显带(C banding) N显带(N banding) 高分辩显带染色体 (high resolution banding chromosome，HRBC),显带后的染色体呈现出独特的带纹即染色体 带型 (banding pattern),荧光染料氮芥喹吖因(quinacrine mustard，QM)显带,Q带(Q banding),反带(reverse band),盐溶液处理，Giems

3、a染色，显示的带与G带相反,R带(R banding),T带(T banding),加热，Giemsa 染色，端粒特异性深染,端粒(telomere)含有TTAGGG重复序列,C带(C banding),NaOH碱处理再Giemsa染色，使着丝粒和1、9、16号次缢痕以及Y染色体长臂远端的2/3的区段显带,N带(N banding pattern),AgNO3染色可使核仁组织区(NOR)银染(Ag-NOR)受染的是与 rDNA 转录有关的一种酸性蛋白,染色体的成份是核酸（DNA和RNA）和蛋白质（组蛋白和非组蛋白）。染色体经胰蛋白酶处理后，蛋白质因被水解而使DNA分子中的碱基暴露， 由于碱基中

4、G/C和A/T的比例不同，对染料结合的程度不一样A/T碱基成份多，则 Giemsa染料易与它结合而深染G/C碱基成份多，则 Giemsa染料不易与其结合而浅染。染色体纵轴上呈现明暗相间或深浅不一的带纹,技术原理,G带(G banding),Chromosome specimens are dealed with alkali and Trypsase(parenzyme), and then stained by Giemsa, we can observe the alternate with bands of deep color and light color under the mic

5、roscope.,A 一秃头来二蛇腰 三似蝴蝶翩翩飘,B 四像鞭炮五黑腰C 六号似小白脸,C 七盖八下 九细腰 七(短臂远端处深染) 八(着丝粒下部深染) 九(着丝粒下部浅染),C 十号臂三深带 十一宽来十二窄 十一(长臂近中段浅带宽) 十二(长臂近中段浅带窄),C X 深带一担挑,D十三下来十四中 十五深染头上瞧 十三下(下部深染) 十四中(中部深染) 十五上(上部深染),E 十六深带连着点 十七长臂带脚镣 十八人黑肚皮白,F 十九中间一点黑 二十头重脚轻飘,G二十一似三角形 二十二似羽毛球 老Y 貌似宝葫芦,四、人类染色体命名国际体制,人类细胞遗传学命名的国际体制 An Internati

6、onal System for Human Cytogenetics Nomenclature, ISCN,界标(landmark)、区(region)、带(band),Landmark：it is stable and Obvious(remarkable) morphological characteristicson chromosome. Including：the end of two arms,centromere, boundary between the regions.,Question：How to understand that the landmark band is

7、the first band of the next region？,Region：the region between the two adjacent(neighboring) landmarks. The nomenclature of regions begin from centromere, the first region is the closest centromere, then the follows are named the second region, the third region, the fourth region in turn,Band：Chromoso

8、me band is continuous and without non-band areas. The nomenclature of band also begins from centromere, It is the first band, the second band, the third band, the fourth band, the fifth band, the sixth band in turn. named just like region.,For example, 1p35means band 5, region 3 of short arm of chro

9、mosome 114q32means band 2, region 3 of long arm of chromosome 14,命名(Nomenclature),When marking(indication) a band, we need to indicate in turn(no need spacing or adding punctuation): number of chromosome. number of arm. number of region. number of band.,1p31 1号染色体短臂3区1带,1q42 1号染色体长臂4区2带,界标是下一区的第一带,高

10、分辨显带染色体,High resolution banding chromosome，HRBC,一套单倍体染色体带纹仅 320条。染色体高分辨带型可显示550-850条带纹，有助于发现更细微的染色体结构异常,1p31.1、1p31.2、1p31.3,The figure shows the chromosome 1, please answer the questions.,How many regions are the short arm divided into? how many bands does each regions contain?What is the meaning o

11、f 1q23? According to the rules of human chromosome nomenclature, write the band name of the short arm end. Label 1q32 on the figure with an arrows.,What is the meaning of 1q23? 1q23 means band 3, region 2 of long arm of chromosome 1.According to the rules of human chromosome nomenclature, write the

12、band name of the short arm end. 1p36 Label 1q32 on the figure with an arrows.,1q32,How many regions are the short arm divided into? how many bands does each regions contain? The short arm of No.1 are divided into three regions. the first region has three bands. the second region has two bands. the t

13、hird region has six bands.,五、染色体的多态性,(chromosomal polymorphism),染色体的结构、带纹宽窄和着色强度等存在恒定的微小变异，染色体多态性主要在结构异染色质区，通常没有明显表型效应或病理学意义,1、Y的长度变异存在种族差异，变异部位是 Y长臂远端的2/3区段的长度变异。如果Y染色体大于F组或大于第18号染色体，称长Y、大Y或巨Y、描述为Yq+；如Y的长度为G组染色体长度的1/2以下，称小Y染色体，描述为Yq-(罕见)。2、D组、G组近端着丝粒染色体的短臂、随体及随体柄部次缢痕区(NOR)变异。3、第1、9 和16号染色体次缢痕的变异及着丝粒异染色质区多态性的倒位。,