痴線，咁多人識少少就不斷趁機拋書包話因為多左條染色體，一係就一句病徵就當答左，全部都答唔對題。
唔識答就收聲啦
假設多出黎果條chromosome係有A, B, C gene
每個有down syndrome既人都會多左A,B,C gene
咁每個人多左出黎既野都係一樣，所以個樣就會好似
唔係咁簡單
1. 重點在於difference in genes in coding region among all "extra 21st chromosome"
2. 每一位Down syndrome 病人既extra 21st chromosome 一定來自爸爸/媽媽一方
-> 但每一個人既genes in coding region for phenotypic expression 根本唔同，not to mention the extra 21st chromosome(more accurately the extra chromatin since protein synthesis takes place before the duplication of chromosomes)
-> 所以你既推論話各自多A B C唔係完全正確，因為 A B C phenotype 既gene differences vary from ppl to ppl
利申：17dse
事實上其實佢地樣貌有分別，但「分別程度」未必我地正常人可以觀察到
但點解有common features(phenotypic expression):
我估計「可能，只係可能」，根本人體21st a pair of homologous chromosome上，differences in genes in coding region among all individuals 分別唔大gwa
Gene coding region就算喺唔同individuals都係conserved
個code會可能有啲唔同，但個sequence同個位置基本上係conserved，稱為consensus sequence
某啲gene嘅sequence of coding regions直頭係conserved across species
所以down syndrome patient個樣會似係因為佢地出事嘅係同一條chromosome，咁啱係控制緊同一樣野
點解我地會分唔到就係好似條reddit link入面咁講
我地係唔擅於分辨唔係自己族/常見嘅人嘅樣
好似白人覺得亞洲人一樣樣，我地覺得佢地又係一樣樣咁
如果你細睇係會睇得出down syndrome patient佢地個樣唔同
但平時冇咩接觸嘅情況下，你每見一過都只會記得佢大概嘅面部輪廓
到你見到下一個嘅時候用腦入面嘅印象嚟對比就自然會覺得佢地係一樣樣
因為你只係留意到佢地嘅大致輪廓
thanks bro
但照計即使係conserved region也好, sequence among individuals都會唔同(呢樣野解釋到即使相同conserved region for a specific characteristics(phenotypic expression), 但容許有different traits of a character
所以我有一點唔明在於，即使down syndrome patient 出事全部在於extra 21 chromosome, 但每一條distinct chromosome 上既sequence都唔同，即使控制同一樣都好，都會好'唔同expression'
但點解你話因為咁岩，所以'好似'?
應該咁講
就算係different traits都好
如果某啲mutation嘅phenotypic effect夠大的話
Trait difference係可以變到insignificant
假設某啲人個鼻尖到人中有2cm，稱為高鼻
某啲人個鼻尖到人中得1cm，稱為扁鼻
如果有某樣genetic mutation可以大幅度㩒低鼻嘅高度嘅
當兩面都咁上下扁嘅時候
望落去就會好似冇分別咁
之後就係呢個post一路有人講嗰樣野
就係我地唔擅長分辨唔係自己種族/唔常見到嘅人
