Exome and whole-genome sequencing Flashcards
(25 cards)
What is the primary purpose of exome sequencing?
To identify genes underlying mendelian conditions
What technology has dramatically reduced the cost of DNA sequencing?
Next-generation sequencing
What percentage of the human genome do exons represent?
Less than 2%
What is the first step in the exome sequencing process?
DNA is randomly sheared
What is used to enrich the library for sequences corresponding to exons?
Hybridization capture
On average, how many single nucleotide variants does exome sequencing identify per person?
20,000 to 25,000
What percentage of variants identified in exome sequencing are typically polymorphisms?
More than 95%
What does the presence of a stop codon indicate in variant prioritization?
Typically more pathogenic than single amino acid substitutions
What is the significance of a variant being highly conserved across species?
It implies functional significance
What is the benefit of comparing candidate variants among affected individuals?
Suggests that the gene is causal if multiple novel variants are found
What is a limitation of exome sequencing?
Difficulty in accurately inferring small deletions and insertions
What is the expected outcome of whole-genome sequencing compared to exome sequencing?
More comprehensive variant identification
What are some examples of epigenetic factors that can affect gene expression?
Methylation, histone modification, chromatin regulation
What type of diseases are increasingly being studied using exome and whole-genome sequencing methods?
Common, complex diseases such as diabetes and hypertension
What is the relationship between environmental factors and epigenetic changes?
Environmental factors can alter regulatory elements affecting gene expression
What is the significance of identifying multiple de novo events in the same gene?
Suggests the gene plays a role in causing the condition
What do genetic variants found in the general population typically indicate?
Less likely to be disease-causing
What is the expected inheritance pattern for autosomal recessive conditions?
Pathogenic variants should be present in both parents
List some well-known mendelian disease-causing genes.
- BRCA1
- Cystic fibrosis transmembrane regulator (CFTR)
- Huntington protein
- SOD1
- FMR1
What is the gene associated with Retinoblastoma?
pRB tumor suppressor
Located at 13q14.1-q14.2
What gene is associated with Sickle cell disease?
β-Globin component of hemoglobin
Located at 11p15.5
Which gene is linked to Tay–Sachs disease?
Hexosaminidase A
Located at 15q23-q24
Fill in the blank: ATPase refers to _______.
adenosine triphosphatase
Fill in the blank: GMP stands for _______.
guanosine monophosphate
