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
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.
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.
CPK: Creatine phosphokinase, an enzyme released from damaged muscle cells. High levels of CPK in the blood, along with clinical features typical of DMD, most likely mean the boy has Duchenne.
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.
Dystrophin: The muscle protein that boys with DMD can't produce. Without dystrophin, the muscle cells gradually die.
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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).
Gentamycin: An antibiotic that had some success in producing dystrophin in mice that had a premature stop codon in their dystrophin gene.
Gower's maneuver: A typical sign of Duchenne in which a boy rises to a standing position by pushing his upper body upright with his arms on his legs.
Guanine: One of the four bases that make up DNA. Abbreviated with a 'G'.
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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 of a gene) from each other.
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M
Macrophage: A type of white blood cell that engulfs foreign cells or debris from dead cells.
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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S
Satellite cell: A type of cell associated with muscle cells. Satellite cells regenerate damaged or dead muscle cells.
Sex-linked: Refers to genetic disorders that only affect males.
Stop codon: The three letter code in a gene that signals the end of the gene. A mutation that causes a stop codon to appear in the middle of a gene will prematurely halt the reading of that gene.
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T
Thymine: One of the four bases that make up DNA. Abbreviated with a 'T'.
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