Term
1. Visibly darkened areas on autoradiograms that represent the location of alleles on a gel.
2. Alternating dark and light areas visible on chromosomes after certain types of stains are used. |
|
Definition
|
|
Term
| A gene that, on the basis of known properties or protein product, is thought to be the gene causing a specific genetic disease. |
|
Definition
|
|
Term
| A unit of measure of the frequency of recombination between the two loci, also known as a map unit. One of these refers to a recombination frequency of 1%. |
|
Definition
|
|
Term
| A process in which overlapping clones are used to progress along a chromosome toward a gene of interest. |
|
Definition
|
|
Term
| The exchange of genetic material between homologous chromosomes during meiosis. |
|
Definition
|
|
Term
| The insertion of normal genes into a cell to correct a disease. |
|
Definition
|
|
Term
| The ordering of genes on chromosomes according to recombination frequency. |
|
Definition
|
|
Term
| A statistic that measures the probability of an event or a series of events. |
|
Definition
|
|
Term
| Describes two loci that are located close enough on the same chromosome that their recombination frequency is less than 50%. |
|
Definition
|
|
Term
| A synthetic lipid particle designed to transport DNA for efficient introduction into a target cell. |
|
Definition
|
|
Term
| The chromosome location of a specific gene. |
|
Definition
|
|
Term
| A common logarithm of the ratio of the likelihood of linkage at a specific recombination fraction to the likelihood of no linkage. |
|
Definition
|
|
Term
| Polymorphisms, such as RFLPs, VNTRs, and microsatellite repeats, that are linked to a disease locus. |
|
Definition
|
|
Term
| A gene expression assay in which mRNA on a blot is hybridized with a labeled probe. Similar to Southern blot except it is RNA which is run on the gel instead of DNA. |
|
Definition
|
|
Term
| The determining of physical distances between genes using cytogenetics and mapping techniques . |
|
Definition
|
|
Term
| A locus in which two or more alleles have gene frequencies greater than 0.01 in in a population. |
|
Definition
|
|
Term
| The isolation and cloning of a gene a disease gene after determining its approximate physical location; the gene product is subsequently determined. |
|
Definition
|
|
Term
| In molecular genetics, a labeled substance, such as a DNA segment, that is used to identify a gene, mRNA transcript, or gene product, usually through hybridization of the probe with the target. |
|
Definition
|
|
Term
| The occurrence among offspring of new combination of alleles, resulting from cross-overs that occur during parental meiosis. |
|
Definition
|
|
Term
| The proportion of meioses in which recombinants between two loci are observed. |
|
Definition
|
|
Term
| Variations in DNA sequence in populations, detected by digesting DNA with a restriction endonuclease, electrophoresing the resultant restriction fragments, transferring the fragments to a blot, and hybridizing the blot with a labeled probe. |
|
Definition
| RFLP (Restriction Fragment Length Polymorphism) |
|
|
Term
| Laboratory procedure in which DNA fragments that have been electrophoresed through a gel are transferred to a solid membrane, such as nitrocellulose. The DNA can then be hybridized with a labeled probe and exposed to X-ray film. |
|
Definition
|
|
Term
| A type of polymorphism created by variation in the number of minisatellite repeats in a defined chromosomal region. |
|
Definition
| VNTR (Variable Number of Tandem Repeats) |
|
|
Term
| Blotting technique analogous to Southern blotting, for detecting proteins, usually by immunologic techniques (ie recognition by specific antibody). |
|
Definition
|
|
Term
| A type of mutation in which the altered protein product in a heterozygote forms a complex with the normal protein product produced by the homologous normal gene, thus disabling it. |
|
Definition
|
|
Term
| The conversion of one gene's sequence to that of another. |
|
Definition
|
|
Term
| Describes a locus or loci at which a deletion or other process has converted the locus from heterozygosity to homozygosity or hemizygosity. |
|
Definition
| Loss of heterozygosity (LOH) |
|
|
Term
| Failure of homologous chromosomes (in mitosis or meiosis I) or sister chromatids (meiosis II) to separate properly into different progeny cells. Can produce aneuploidy. |
|
Definition
|
|
Term
| Loss of an allele such that a cell only expresses one form of the allele, or duplication of an allele, and loss of the second allele, such that only homozygous alleles are expressed. |
|
Definition
| Reduction of homozygosity |
|
|
Term
| A gene whose product helps to control cell growth and proliferation: mutations in thesen can lead to cancer. |
|
Definition
|
|
Term
| A finger shaped protein structural motif found in DNA-binding proteins and characterized by two cysteines and two histidines (or four cysteines) bound to a zinc ion. By inserting into the wide groove of DNA, these fingers help the protein to bind DNA. |
|
Definition
|
|
Term
| A feature of pedigrees in which a disease is seen at earlier ages or with increased severity in more recent generations. |
|
Definition
|
|
Term
| A type of mutation in which a tandem trinucleotide repeat increases in number. |
|
Definition
|
|
Term
| The presence in a cell of two chromosomes derived from a single parent and none from the other parent (disomy). In this, the two chromosomes are the nonidentical homologous chromosomes. |
|
Definition
|
|
Term
| The presence in a cell of two identical chromosomes derived from one parent and none from the other parent. |
|
Definition
|
|
Term
| Describes process in which genetic material is expressed differently when inherited from the mother than when inherited from the father. |
|
Definition
|
|
Term
| The absence of a phenotype in a person known to carry a specific mutant gene. |
|
Definition
|
|
Term
| In a population, the proportion of individuals possessing a disease-causing genotype who express the disease phenotype. When this proportion is less than 100%, the disease genotype is said to have reduced or incomplete penetrance. |
|
Definition
|
|
Term
| DNA sequences that occur in multiple copies located directly next to one another. |
|
Definition
|
|
Term
| Condition in which two copies of one chromosome are derived from a single parent, and no copies are derived from the other parent. May be either isodisomy or heterodisomy. |
|
Definition
|
|
Term
| A trait in which the same genotype may produce phenotypes of varying severity or expression. |
|
Definition
|
|
Term
| Grouping of cells from the intestine which show an abnormality of cell proliferation and a failure of cellular maturation. Initially the cells are benign or noninvasive; the accumulation of further mutations leads to invasiveness, and the development of adenocarcinoma. |
|
Definition
|
|
Term
| Sequence of DNA that is complementary to part of an mRNA, used to specifically inhibit expression of that gene. |
|
Definition
| Antisense oligonucleotide |
|
|
Term
| Tumors derived from epithelial cells. Adenocarcinomas are tumors derived from intestinal epithelial cells which first formed adenomas, and then gathered additional mutations to become invasive, and a carcinoma. |
|
Definition
|
|
Term
| A technology whereby DNA fragments are “fixed” on a glass or silicon chip in an ordered array and unknown samples are hybridized to the chip. Spots at which hybridization occur are detected via fluoresence and indicate a positive signal with the DNA on the chip. Up to 6,000 different DNA fragments can be screened on one chip, allowing this to be a fast and efficient method for screening populations for genetic mutations. Also known as microarrays. |
|
Definition
|
|
Term
| An alteration of DNA in which a duplication or deletion occurs that is not a multiple of three base pairs. |
|
Definition
|
|
Term
| The non-reciprocal transfer of information between homologous genes as a consequence of heteroduplex formation, followed by repair of mismatches in the heteroduplex. In this context, this is associated with two crossover events. |
|
Definition
|
|
Term
| Exchange of genetic material between two DNA fragments presenting sequence homology. |
|
Definition
|
|
Term
| The attachment of methyl groups; in genetics, refers especially to the addition of methyl groups to cytosine bases, forming 5-methyl-cytosine. This is correlated with reduced transcription of genes. |
|
Definition
|
|
Term
| An alteration in DNA sequence. |
|
Definition
|
|
Term
| A gene that can transform cells into a highly proliferative state, causing cancer. |
|
Definition
|
|
Term
| Cloning vector derived from P1 bacteriophage that can accommodate large inserts of foreign DNA. |
|
Definition
|
|
Term
| The isolation and cloning of a disease gene after determining its approximate location by linkage analysis; the gene product is then subsequently determined. |
|
Definition
|
|
Term
| A test designed to determine if a specific sequence of DNA encodes a premature stop codon, such that a truncated protein is synthesized instead of the full length protein. |
|
Definition
|
|
Term
| a segment of DNA consisting of a multiply repeated short sequence element. Repeats of a 2 bp unit are referred to as dinucleotides, those with 3 bp as trinucleotides, etc. Longer repeats are particularly likely to have multiple polymorphic alleles with variable lengths. Polymorphic SSR’s are a major source of genetic markers for the human genome project. |
|
Definition
| Simple Sequence repeat (SSR) markers (microsatellite regions) |
|
|
Term
| A gene whose product helps to control cell growth and proliferation; mutations in tumor suppressors can lead to cancer. An example is the retinoblastoma gene, Rb. |
|
Definition
|
|
Term
| A synthesized yeast chromosome capable of carrying a large insert of foreign DNA (up to 1,000 kbases). |
|
Definition
| Yeast artificial chromosome (YAC) |
|
|
Term
| In a population, the proportion of chromosomes that contain a specific allele. |
|
Definition
|
|
Term
| A statistic that measures the proportion of genes shared by two individuals as a result of descent from a common ancestor. |
|
Definition
| Coefficient of relationship |
|
|
Term
|
Definition
|
|
Term
| Risk estimate based upon direct observation of data. |
|
Definition
|
|
Term
| Individuals who shares 50% of their genome. eg. Parent and child, or dizygous sibling. |
|
Definition
|
|
Term
| Specifies an equilibrium relationship between gene frequencies and genotype frequencies in populations. |
|
Definition
|
|
Term
| A primary morphological defect resulting from an intrinsically abnormal development process. |
|
Definition
|
|
Term
| Describes traits or diseases that are the product of the interaction of multiple genetic and environmental factors, such as neural tube defects. |
|
Definition
|
|
Term
| The probability that a couple will produce a child with a genetic disease. Refers to couples who have not yet had a child with the disease in question. Compare this to recurrence risk. |
|
Definition
|
|
Term
| Describes a trait caused by the combined additive effects of multiple genes. |
|
Definition
|
|
Term
| Branch of genetics dealing with genetic variation and genetic evolution of populations. |
|
Definition
|
|
Term
| The first person in a pedigree to be identified clinically as having the disease in question. |
|
Definition
|
|
Term
| The probability that another affected offspring will be produced in families in which one or more affected offspring will be produced in families in which one or more affected offspring have already been produced. |
|
Definition
|
|
Term
| Individuals who share 25% of their genome eg. first cousins |
|
Definition
|
|
