孕妇DNA血检可查出唐氏综合症

choi

本文通过一路BBS站telnet客户端发布

BBC Chinese, Jan 12, 2011.
http://www.bbc.co.uk/zhongwen/simp/world/2011/01/110112_dna_test.shtml

My comment: The report is based on

Chiu RWK et al, Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study. British Medical Journal,  342: c7401 (2011).
http://www.bmj.com/content/342/bmj.c7401

(a) Quote from FULL TEXT (which is available free online by clicking the button in the upper left corner of the web page):

"Cell-free DNA from the fetus has been found in the plasma of pregnant women, and this has been used successfully for non-invasive determination of the fetal sex and fetal RhD genotype in RhD negative women." Introduction.

"We extracted and sequenced DNA molecules from 2.0–4.8 mL of maternal plasma using a protocol similar to that reported previously but with the introduction of multiplexing.24 27 DNA molecules exist in maternal plasma as short fragments. Methods.

(b) My comment:
(i) For RhD, see Rh blood group system
http://en.wikipedia.org/wiki/Rh_blood_group_system
(The Rh blood group system (including the Rh factor) is one of the currently 30 human blood group systems. It is clinically the most important blood group system after ABO. The Rh blood group system currently consists of 50 defined blood-group antigens, among which the 5 antigens D, C, c, E, and e are the most important ones. The commonly-used terms Rh factor, Rh positive and Rh negative refer to the D antigen only.)
(ii) I do not know the meaning of multiplexing, which is under the heading "Maternal plasma DNA sequencing" in Methods of full text.

(iii) sensitivity and specificity
http://en.wikipedia.org/wiki/Sensitivity_and_specificity
(Sensitivity measures the proportion of actual positives which are correctly identified as such (e.g. the percentage of sick people who are correctly identified as having the condition). Specificity measures the proportion of negatives which are correctly identified (e.g. the percentage of healthy people who are correctly identified as not having the condition).)


----------------------Separately
人在30多岁时记忆力最好. VOA Chinese, Jan 11, 2011.
http://www.voanews.com/chinese/news/20100111-Facial-Recognition-113295214.html

Quote:

"人的脑力在二十几岁的时候最好，例如记忆姓名和迅速处理新信息的能力.

哈佛大学心理学系研究生劳拉·杰明发现，记住别人面孔的能力"到30岁出头时才到达颠峰."

My comment: That is Laura Germine, a graduate student in Psychology Department at Harvard University.
http://www.people.fas.harvard.edu/~lgermine/index.html

Click "publications" at the top horizontal bar and one will find the article at issue.

Germine, L., Duchaine, B., and Nakayama, K. (in press) Where cognitive development and aging meet: Face learning ability peaks after age 30. Cognition.

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choi

本文通过一路BBS站telnet客户端发布

BBC Chinese, Jan 12, 2011.
http://www.bbc.co.uk/zhongwen/simp/world/2011/01/110112_dna_test.shtml

My comment: The report is based on

Chiu RWK et al, Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study. British Medical Journal,  342: c7401 (2011).
http://www.bmj.com/content/342/bmj.c7401

(a) Quote from FULL TEXT (which is available free online by clicking the button in the upper left corner of the web page):

"Cell-free DNA from the fetus has been found in the plasma of pregnant women, and this has been used successfully for non-invasive determination of the fetal sex and fetal RhD genotype in RhD negative women." Introduction.

"We extracted and sequenced DNA molecules from 2.0–4.8 mL of maternal plasma using a protocol similar to that reported previously but with the introduction of multiplexing.24 27 DNA molecules exist in maternal plasma as short fragments. Methods.

(b) My comment:
(i) For RhD, see Rh blood group system
http://en.wikipedia.org/wiki/Rh_blood_group_system
(The Rh blood group system (including the Rh factor) is one of the currently 30 human blood group systems. It is clinically the most important blood group system after ABO. The Rh blood group system currently consists of 50 defined blood-group antigens, among which the 5 antigens D, C, c, E, and e are the most important ones. The commonly-used terms Rh factor, Rh positive and Rh negative refer to the D antigen only.)
(ii) I do not know the meaning of multiplexing, which is under the heading "Maternal plasma DNA sequencing" in Methods of full text.

(iii) sensitivity and specificity
http://en.wikipedia.org/wiki/Sensitivity_and_specificity
(Sensitivity measures the proportion of actual positives which are correctly identified as such (e.g. the percentage of sick people who are correctly identified as having the condition). Specificity measures the proportion of negatives which are correctly identified (e.g. the percentage of healthy people who are correctly identified as not having the condition).)


----------------------Separately
人在30多岁时记忆力最好. VOA Chinese, Jan 11, 2011.
http://www.voanews.com/chinese/news/20100111-Facial-Recognition-113295214.html

Quote:

"人的脑力在二十几岁的时候最好，例如记忆姓名和迅速处理新信息的能力.

哈佛大学心理学系研究生劳拉·杰明发现，记住别人面孔的能力"到30岁出头时才到达颠峰."

My comment: That is Laura Germine, a graduate student in Psychology Department at Harvard University.
http://www.people.fas.harvard.edu/~lgermine/index.html

Click "publications" at the top horizontal bar and one will find the article at issue.

Germine, L., Duchaine, B., and Nakayama, K. (in press) Where cognitive development and aging meet: Face learning ability peaks after age 30. Cognition.

--