A
Adenine: One of the four bases that make up DNA. Abbreviated with an 'A'.
Ashkenazi Jews: Refers to Jews of Eastern European descent.
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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
Carrier: A person that carries a gene that causes a disorder, but does not show symptoms.
Chromosome: Chromosomes are packages of DNA found in the nucleus of cells. Humans have 46 chromosomes.
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: Refers to genetic disorders in which a person only needs one copy of the mutated gene to develop the disorder.
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E
Enzyme: An enzyme is a protein that has a specific action in a chemical or biochemical reaction.
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G
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).
GM2 ganglioside: A component of cellular membranes, usually broken down by hexosaminidase A in the lysosome.
Guanine: One of the four bases that make up DNA. Abbreviated with a 'G'.
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H
Hexosaminidase A (HEX A): Enzyme that degrades GM2 gangliosides into its component parts. HEX A has two subunits, alpha and beta, and an activator unit. The alpha subunit is missing or otherwise non-functional in people with Tay-Sachs.
Hexosaminidase B (HEX B): Enzyme that degrades gangliosides into its component parts. HEX B has two beta subunits, and an activator unit. The beta subunit is missing or otherwise non-functional in people with Sandhoff disease. This means both HEX A and HEX B are non-functional.
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L
Lysosome: Cellular organelle where large complicated molecules are broken down into component parts to be reused for other reactions. Lysosomes also store molecules that can't be broken down and reused.
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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.
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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S
Sandhoff: A disorder with symptoms similar to Tay-Sachs caused by non-functional hexaminidase A and B enzymes. The beta subunits of hexaminidase A and B are missing or otherwise non-functional.
T
Thymine: One of the four bases that make up DNA. Abbreviated with a 'T'.
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