21號染色體

人類的21號染色體是23對染色體的其中之一，正常狀況下每個細胞擁有兩條。此染色體是所有人類染色體中最小的一個，含有大約4700萬個鹼基對，佔細胞內所有DNA的1.5%。

21號染色體
物種	Homo sapiens
基因數量	200-400

21號染色體的定序是在2000年宣布完成，是人類基因組計畫中第二條定序完成的人類染色體。此染色體內大約含有300到400個基因，依預測方式而有所不同。

相關疾病

• 阿茲海默症第一型
• 肌肉萎縮性側索硬化症（漸凍人症）第一型
• 唐氏症候群
• Holocarboxylase synthetase deficiency
• Homocystinuria
• Jervell and Lange-Nielsen syndrome
• Leukocyte adhesion deficiency
• Nonsyndromic deafness
• Nonsyndromic deafness, autosomal recessive
• Romano-Ward syndrome

参考文献

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