A
Adenine: One of the four bases that make up DNA. Abbreviated with an 'A'.
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B
Base: A small molecule inside the larger molecule of DNA. Bases - A, C, G, and T - are arranged in line in a DNA molecule (e.g. CGGTACAGG) and encode instructions for making proteins.
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C
CAG: Triplet codon that codes for glutamine. The number of CAG repeats is higher in the IT-15 gene of people with Huntington.
Chromosome: Chromosomes are packages of DNA found in the nucleus of cells. Humans have 46 chromosomes.
Codon: Three letters of bases in a gene that encode the type of amino acid to be placed in the protein. For example, the codon G-T-G signifies the amino acid valine.
Cytosine: One of the four bases that make up DNA. Abbreviated with a 'C'.
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D
DNA: Short for deoxyribonucleic acid, DNA is the molecule that carries genetic information.
Dominant: A genetic trait or disorder is dominant when only one copy of the mutated gene is necessary for the trait to develop. A recessive trait or disorder develops when two copies of the mutated gene are inherited.
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E
Enzyme: Protein that helps other chemical reactions in the body proceed.
Exon: A section of a gene that contains the instructions for making a protein.
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G
Gel: Hard Jello-like substance that scientists use to measure the size of DNA fragments during DNA diagnostic tests.
Gene: A portion of DNA that contains instructions for making a protein.
Genotype: The genetic composition of a person. Usually used when considering one gene or chromosome (e.g., males have a XY genotype, females have a XX).
Glutamine: One of 20 amino acids. People with Huntington have more glutamines in the huntingtin protein because of the increased number of CAG repeats.
Guanine: One of the four bases that make up DNA. Abbreviated with a 'G'.
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H
Huntingtin: The protein made by the IT-15 gene. People with Huntington have a huntingtin protein with more glutamines.
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I
Intron: A section of a gene that does not contain any instructions for making a protein. Introns separate exons -- the coding sections -- from each other.
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M
Mutation: A change in the genetic code (the A's, C's, G's and T's) of a gene.
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P
PCR/Polymerase chain reaction: A method to increase or amplify specific sections of DNA. This method can be used to detect changes in genes that cause genetic disorders.
Primer: A small DNA molecule used to perform PCR.
Protein: A type of molecule produced by the body. The instructions for producing proteins reside in the genes.
Punnett square: A method of showing the potential offspring of two parents.
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R
Recessive: Refers to genetic disorders in which a person must have two copies of the mutated gene to develop the disorder.
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T
Thymine: One of the four bases that make up DNA. Abbreviated with a 'T'.
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