醫(yī)學(xué)遺傳學(xué)——染色體分組、核型與顯帶

1、第二節(jié) 染色體分組、核型與顯帶,Section two Chromosome grouping, karyotype and banding,1960年在美國丹佛(Denver)第一屆國際細(xì)胞遺傳學(xué)會議確定人類染色體分組按染色體大小遞減次序和著絲粒位置劃分Denver體制,110頁,一、染色體分組(Chromosome grouping),1-22號常染色體和X、Y性染色體形成24個基因連鎖群(linkage group),,女性

2、：46，XX,男性：46，XY,二、染色體非顯帶核型,（The karyotype of non-banding chromosome）,非顯帶核型分析(karyotype analysis),三、染色體顯帶(chromosome banding),Q顯帶(Q banding) G顯帶(G banding) R顯帶(R banding) T顯帶(T banding) C顯帶(C banding) N顯帶(N

3、 banding) 高分辯顯帶染色體 (high resolution banding chromosome，HRBC),顯帶后的染色體呈現(xiàn)出獨特的帶紋即染色體 帶型 (banding pattern),熒光染料氮芥喹吖因(quinacrine mustard，QM)顯帶,Q帶(Q banding),反帶(reverse band),鹽溶液處理，Giemsa染色，顯示的帶與G帶相反,R帶(R banding),T帶(T ban

4、ding),加熱，Giemsa 染色，端粒特異性深染,端粒(telomere)含有TTAGGG重復(fù)序列,C帶(C banding),NaOH堿處理再Giemsa染色，使著絲粒和1、9、16號次縊痕以及Y染色體長臂遠(yuǎn)端的2/3的區(qū)段顯帶,N帶(N banding pattern),AgNO3染色可使核仁組織區(qū)(NOR)銀染(Ag-NOR)受染的是與 rDNA 轉(zhuǎn)錄有關(guān)的一種酸性蛋白,染色體的成份是核酸（DNA和RNA）和蛋白質(zhì)（組蛋白

5、和非組蛋白）。染色體經(jīng)胰蛋白酶處理后，蛋白質(zhì)因被水解而使DNA分子中的堿基暴露， 由于堿基中G/C和A/T的比例不同，對染料結(jié)合的程度不一樣A/T堿基成份多，則 Giemsa染料易與它結(jié)合而深染G/C堿基成份多，則 Giemsa染料不易與其結(jié)合而淺染。染色體縱軸上呈現(xiàn)明暗相間或深淺不一的帶紋,技術(shù)原理,G帶(G banding),Chromosome specimens are dealed with alkali and T

6、rypsase(parenzyme), and then stained by Giemsa, we can observe the alternate with bands of deep color and light color under the microscope.,A 一禿頭來二蛇腰 三似蝴蝶翩翩飄,B 四像鞭炮五黑腰C 六號ｐ似小白臉,C 七蓋八下 九細(xì)腰 七(短臂遠(yuǎn)端處深染) 八(著絲粒下部深染)

7、 九(著絲粒下部淺染),C 十號ｑ臂三深帶 十一寬來十二窄 十一(長臂近中段淺帶寬) 十二(長臂近中段淺帶窄),,C X 深帶一擔(dān)挑,D十三下來十四中 十五深染頭上瞧 十三下(下部深染) 十四中(中部深染) 十五上(上部深染),E 十六深帶連著點 十七長臂帶腳鐐 十八人黑肚皮白,F 十九中間一點黑 二十頭重腳輕飄,G二十一似三角形 二十二似羽毛球 老Y 貌似寶葫

8、蘆,四、人類染色體命名國際體制,人類細(xì)胞遺傳學(xué)命名的國際體制 An International System for Human Cytogenetics Nomenclature, ISCN,㈠界標(biāo)(landmark)、區(qū)(region)、帶(band),Landmark：it is stable and Obvious(remarkable) morphological characteristicson chromosome

9、. Including：⑴the end of two arms,⑵centromere, ⑶boundary between the regions.,Question：How to understand that the landmark band is the first band of the next region？,Region：the region between the two adjacent(neighbori

10、ng) 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：Chromosome ban

11、d 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

12、 like region.,,For example, 1p35means band 5, region 3 of short arm of chromosome 114q32means band 2, region 3 of long arm of chromosome 14,㈡命名(Nomenclature),When marking(indication) a band, we need to indicate in tu

13、rn(no need spacing or adding punctuation): ①number of chromosome. ②number of arm. ③number of region. ④number of band.,1p31 1號染色體短臂3區(qū)1帶,1q42 1號染色體長臂4區(qū)2帶,界標(biāo)是下一區(qū)的第一帶,㈢高分辨顯帶染色體,High resolution banding chromosome，HRBC,一套單倍

14、體染色體帶紋僅 320條。染色體高分辨帶型可顯示550-850條帶紋，有助于發(fā)現(xiàn)更細(xì)微的染色體結(jié)構(gòu)異常,,,1p31.1、1p31.2、1p31.3,The figure shows the chromosome 1, please answer the questions.,⑴How many regions are the short arm divided into? how many bands does each re

15、gions contain?⑵What is the meaning of 1q23? ⑶According to the rules of human chromosome nomenclature, write the band name of the short arm end.⑷ Label 1q32 on the figure with an arrows.,⑵What is the meaning of 1q23?

16、 1q23 means band 3, region 2 of long arm of chromosome 1.⑶According to the rules of human chromosome nomenclature, write the band name of the short arm end. 1p36⑷ Label 1q32 on the figure with an arrows.,,1q32

17、,,⑴How 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 tw

18、o bands. the third region has six bands.,五、染色體的多態(tài)性,(chromosomal polymorphism),染色體的結(jié)構(gòu)、帶紋寬窄和著色強度等存在恒定的微小變異，染色體多態(tài)性主要在結(jié)構(gòu)異染色質(zhì)區(qū)，通常沒有明顯表型效應(yīng)或病理學(xué)意義,1、Y的長度變異存在種族差異，變異部位是 Y長臂遠(yuǎn)端的2/3區(qū)段的長度變異。如果Y染色體大于F組或大于第18號染色體，稱長Y、大Y或巨Y、描述