Name: genome variation in cnvs and snps
Uploaded: 2021-04-07T12:11:59.000Z
Duration: 2 min 26 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

Biological Evolution: Unity And Diversity

HS-LS4-1

comparing-copy-number-variations-and-snps

Comparing Copy Number Variations and SNPs

يتم ملاحظة الاختلافات الجينومية مثل إضافة أو حذف أجزاء من الحمض النووي بشكل شائع في مجموعة سكانية. يمكن أن تنشأ الاختلافات الجينومية في مجموعة سكانية بسبب تغيرات النيوكليوتيدات المفردة في الحمض النووي أو التغيرات الهيكلية في الكروموسومات.
تباين رقم النسخ أو CNV هو مصطلح شامل يحدد الاختلافات الهيكلية التي تنطوي على أجزاء الحمض النووي لأكثر من 1 كيلو زوج أساسي.
إذا كان الجزء الكروموسومي المعني يحتوي على جين ، فيمكن ل CNVs زيادة عدد نسخ هذا الجين عن طريق الازدواجية والإدراج أو تقليله عن طريق الحذف الذي ينتج عنه نمط وراثي فارغ.
لذلك ، قد يكون لدى بعض الأفراد نسختان أو أكثر من الجين ، أو لا توجد نسخ على الإطلاق. على سبيل المثال ، قد يحمل بعض الأشخاص من أصل وراثي أوروبي نسختين من جين فصيلة الدم Rhesus ، RHD ، بينما قد يكون لدى البعض نسخة واحدة فقط والبعض الآخر لا يحتوي على أي نسخة على الإطلاق.  
يمكن أن يؤثر CNV على الأنماط الظاهرية التي تعتمد على عدد النسخ الجينية الوظيفية. في المناطق الأوروبية الأمريكية والآسيوية حيث تنتشر الأنظمة الغذائية القائمة على النشا ، يظهر السكان عددا أكبر من النسخ من الجين AMY1 ، وهو جين يشارك في استقلاب النشا.
ترتبط CNVs أيضا بالعديد من الأمراض مثل الصدفية ومرض باركنسون والاضطرابات السلوكية مثل التوحد والفصام.
في حين أن CNVs عادة ما تغطي اختلافات كبيرة في تسلسل الحمض النووي ، فإن تعدد أشكال النوكليوتيدات المفردة أو SNPs عبارة عن بدائل عشوائية أحادية القاعدة موجودة في جميع أنحاء الجينوم.
تحدث مثل هذه البدائل الأساسية مرة واحدة كل 1000 نيوكليوتيد؛ ومع ذلك، ليست جميعها مؤهلة على أنها تعدد الأشكال بشكل عام ، يشار فقط إلى تباين النيوكليوتيدات الموجود في أكثر من 1٪ من السكان باسم SNP.
يمكن أن تمنح تعدد الأشكال أمراضا مختلفة مثل مرض السكري أو السرطان. على سبيل المثال ، في المرضى الذين يعانون من فقر الدم المنجلي ، يؤدي استبدال قاعدة واحدة من الأدينين إلى الثايمين في موضع معين من جين بيتا غلوبين إلى خلايا الدم الحمراء المنجلية الشكل.

<ol>
	<li>لي وتشارلز وستيفن دبليو شيرير. "السياق السريري لتباين عدد النسخ في الجينوم البشري". مراجعات الخبراء في الطب الجزيئي 12 (2010).</li>
	<li>بودول وبروس وأنجيلا فان دال. "فئات SNP ذات الصلة من الطب الشرعي". التقنيات الحيوية 44 ، العدد 5 (2008): 603-610.</li>
</ol>

مقارنة اختلافات أرقام النسخ وتعدد أشكال النوكليوتيد المفردة

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لقد فتح تسلسل الجينوم البشري العديد من أسرار الجينوم المحفوظة بشكل أفضل. لقد حدد العلماء الآلاف من الاختلافات الجينومية الموجودة داخل مجتمع ما. يمكن أن تكون هذه الاختلافات نيوكليوتيدًا واحدًا أو اختلافًا كروموسوميًا أكبر.

اختلافات عدد النسخ أو CNVs هي الاختلافات الهيكلية التي تغطي أكثر من 1 كيلو بايت من تسلسل الحمض النووي. من ناحية أخرى، فإن تعدد أشكال النوكليوتيدات المفردة (SNP) هو تغير في النوكليوتيدات المفردة أو طفرة نقطية توجد في أكثر من 1٪ من السكان. يعد كل من CNV وSNPs ذا قيمة كبيرة في دراسات الفحص الجيني وتحليل القرابة.

أشكال تباين عدد النسخ.

هناك خمسة أشكال من CNVs. الأول يسمى الحذف. يمكن أن يؤدي فقدان جزء من الحمض النووي إلى تقليل عدد نسخ الجين أو مجموعة الجينات. والثاني يسمى الازدواجية جنبا إلى جنب. هنا، يتم إدخال نسخة من قطعة الكروموسومات في المنطقة المجاورة. والثالث يسمى الازدواجية غير المتجاورة. هنا، يتضاعف جزء الكروموسوم ويتم إدخاله في منطقة كروموسومية بعيدة أو كروموسوم مختلف. الشكل الرابع يسمى متلازمة الأليلة (Multiallelic CNV ). يتضاعف جزء من الحمض النووي عدة مرات ويؤدي إلى تكوين أليلات متعددة للجين. الشكل الخامس يسمى إعادة الترتيب المعقد. هنا يتضاعف جزء من الحمض النووي وينقلب قبل أن يتم إدخاله مرة أخرى في نفس الكروموسوم أو في كروموسوم مختلف.

تعدد الأشكال النوكليوتيدات واحد

تعدد أشكال النوكليوتيدات المفردة أو SNP هو نوع آخر من التباين الجينومي الذي يتضمن تغييرات في قاعدة نيوكليوتيدات واحدة. لقد حدد العلماء الآلاف من تعدد الأشكال في جميع أنحاء الجينوم البشري، ويتم استخدامها بشكل روتيني كعلامات وراثية للأمراض الموروثة وتحليل الطب الشرعي.

بناءً على تطبيقها، يتم تقسيم SNPs إلى أربعة أنواع. يتم استخدام تعدد الأشكال (SNP) لاختبار الهوية للتمييز بين الأشخاص وإبعاد الأشخاص عن الروابط العائلية. إن تعدد الأشكال (SNPs) المفيد للنسب هو تعدد الأشكال (SNPs) المرتبط بإحكام والذي يساعد في تحديد الأفراد المفقودين في التحليل العائلي. تساعد تعدد الأشكال (SNPs) المعلوماتية الخاصة بالنسب في تحديد أصل الشخص والربطه بخصائصه المظهرية. تحدد تعدد الأشكال (SNPs) المعلوماتي للنمط الظاهري احتمالية وراثة نمط ظاهري معين، مثل لون البشرة ولون العين وما إلى ذلك.
</div>

فتح تسلسل الجينوم البشري العديد من أفضل أسرار الجينوم المحفوظة. حدد العلماء الآلاف من اختلافات الجينوم الموجودة ...

Education

JoVE Core

Molecular Biology

البيولوجيا الجزيئية

Unit 2

الوحدة الثانية

Genomes and Evolution

الجينومات والتطور

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

genome variation in cnvs and snps

Genome variation in CNVs and SNPs shows how DNA can differ across people in a population. These differences may involve a single nucleotide, which is one DNA base, or a larger chromosomal change. Scientists study them to understand inherited variation in the human genome.

Copy number variations, or CNVs, are structural changes that cover more than 1 kb of DNA sequence. A CNV can change the number of copies of a gene or a group of genes. The main forms are deletion, tandem duplication, noncontiguous duplication, multiallelic CNV, and complex rearrangement.

A deletion removes a DNA segment and can lower gene copy number. In tandem duplication, a copied chromosomal segment is inserted next to the original region. In noncontiguous duplication, the copied segment moves to a distant chromosomal region or even a different chromosome. Multiallelic CNV creates several copies and can produce multiple alleles of a gene. In complex rearrangement, a segment duplicates and inverts before it is inserted back into the same or a different chromosome.

Single nucleotide polymorphism, or SNP, is another genomic variation that changes one nucleotide base. A SNP is a point mutation found in more than 1% of the population. Scientists have identified thousands of SNPs across the human genome, and they are widely used as genetic markers in studies of inherited disease and forensic analysis.

SNPs are grouped by use into four types. Identity-testing SNPs help distinguish people and exclude familial connections. Lineage informative SNPs are tightly linked SNPs that help identify missing individuals in family analysis. Ancestry informative SNPs help connect a person's ancestry with related phenotypic traits. Phenotype informative SNPs help estimate the chance of traits such as skin color or eye color.

Genome Variation in CNVs and SNPs

evolutionary relationships through genome comparisons

evolutionary-relationships-through-genome-comparisons

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genome copying errors

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phylogenetic trees

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comparing copy number variations and snps

Genome variation in CNVs and SNPs shows how DNA can differ across people in a population. These differences may involve a single nucleotide, which is one DNA base, or a larger chromosomal change. Scientists study them to understand inherited variation in the human genome. Copy number variations, or CNVs, are structural changes that cover more than 1 kb of DNA sequence. A CNV can change the number of copies of a gene or a group of genes. The main forms are deletion, tandem duplication,...

key terms and concepts

Explore how copy number variations and SNPs change the human genome, from deletions and duplications to ancestry, identity, and phenotype markers.

Genome Variation in CNVs and SNPs | JoVE K12

molecular biology

JoVE Core Molecular Biology showcases the molecular processes of the cell through clear and concise animated video lessons. Additionally, in scientist-in-action videos, these concepts' application is demonstrated through real experiments in modern laboratories.

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Biology

Evolution

Speciation

Tennessee Academic Standards

Heredity

BIO1.LS3.2

Virginia  Standards of Learning

HIgh School

BIO.5

BIO.5.d

Minnesota Academic Standards in Science

Life Science

3.2.1 9L.3.2.1.3

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Biological Evolution: Unity and Diversity

Arizona Science Standards

HS+B.L4

HS+B.L4U1.13

Next Generation Science Standards

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS3-2

new-york-state-science-learning-standards

New York State Science Learning Standards

Inheritance and Variation of Traits

HS-LS3-1.

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This ...

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Apply concepts of statistics and probability to support explanations that populations of organisms adapt when an advantageous heritable trait increases in proportion to organisms lacking this trait. Emphasis is on analyzing shifts in numerical distribution of traits and using these shifts as evidence to support explanations for adaptations. Explanations could include basic statistical or graphical analysis.

HS-LS4-3

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HS-LS4-5

Genome Variation in CNVs and SNPs

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