Introduction including methods (NGS) and nomenclature of genetic variants Flashcards
(23 cards)
What is medical genetics?
Medical genetics involver any application of genetics to medical practice. It thus includes studies of the inheritance of diseases in families, mapping of disease genes to specific locations on chromosomes, analyses of the molecular mechanisms through which genes cause disease, and the diagnosis and treatment of genetic disease. It also includes genetic counseling.
What is a chromosomal disorder?
A disorder in which entire chromosomes (or large segments of them) are missing, duplicated, or otherwise altered. Examples are Down syndrome and Turner syndrome.
What is a single-gene disorder?
A disorder in which a single gene are altered; these are often termed mendelian conditions or single-gene disorders. Examples are cystic fibrosis, sickle cell disease, and hemophilia. The inheritance pattern of single gene disorders are recessive, dominant, X-linked, and mitochondrial
What is multifactorial disorders?
Multifactorial disorders, which results from a combination of multiple genetic and environmental causes. Many birth defects, such as cleft lip and cleft palate, as well as many adult disorders, including heart disease and diabetes, belong in this category.
What is mitochondrial disorders?
Mitochondrial disorders is a relatively small number of diseases caused by alterations in the small cytoplasmic mitochondrial chromosome.
Disorders are classified according to the way they are inherited in families. What is these classifications?
1) Autosomal dominant
2) Autosomal recessive
3) X-linked
What is congenital malformations?
Congenital malformations - also known as birth defects - can be defined as structural or functional anomalies that occur during intrauterine life.
During what processes can errors occur?
Errors can occur in the replication of genetic material or in the translation of genes into proteins. Such errors commonly produce single-gene disorders.
Errors that occur during cell division can lead to disorders involving entire chromosomes.
What are the three basic components of a DNA molecule?
The pentose sugar (deoxyribose), a phosphate group, and four types of nitrogenous bases.
What is a polygenic disorder?
A disorder associated with genetic variants in several genes; each contributing only a small increased risk.
What is pharmacogenetics?
Study of genetic variants that modify human responses to pharmacological reagents.
What is the function of the cytochrome P450 superfamily?
They catalyses hydroxylation or demethylation of >20% of drugs metabolized in the human liver, ex. antidepressants, and some B-blockers.
The most important cytochrome is cytochrome P450 2D6 (CYP2D6)
What are the four steps in Next Generation Sequencing (NGS)?
1) Library preparation
2) DNA library bridge amplification
3) DNA library sequencing
4) Alignment and data analysis
What sequencing methods is defined by NGS?
Panel sequencing, Whole Exome Sequencing (WES), and Whole Genome Sequencing (WGS)
What is the difference between Whole exome sequencing and Whole genome sequencing?
Whole exome sequencing will only sequence the protein-coding regions of the gene (the exons).
Whole genome sequencing will sequence all genes, translocations and non-coding DNA (both introns and exons).
What is the indication type of reference sequences?
Coding DNA = c.
Genomic DNA = g.
Mitochondrial DNA = m.
RNA = r.
Protein = p.
How is nucleotides numbered?
There is no nucleotide 0.
Nucleotide 1 is the A of the ATG-translation initiation codon.
Nucleotides 5´of ATG initiation codon is -1, -2, etc.
Nucleotides 3´of the translation stop codon is *1, *2, etc.
How is DNA changes showed in the nomenclature?
Substitutions: X>Y
Insertions: “ins” after nucleotides flanking the insertion site, followed by a description of the nucleotides inserted. Ex. c.76_77insT.
Deletions: “del” after the first and last nucleotide(s) deleted. Ex. c.7_8del.
Duplication: “dup” after the nucleotide(s) duplicated. Ex. c.76dupT.
What is the start codon and the three stop codons?
Start: Met
Stop: UAA, UAG, and UGA
How is an change in different alleles noted?
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What is a silent mutation?
A change in nucleotide which not change the amino acid.
What is a nonsense mutation?
A change in a nucleotide where the triplet is changed to a stop codon.
What is a missense mutation?
A missense mutation is a DNA change that results in different amino acids being encoded at a particular position in the resulting protein.
