Allelic ladders for short tandem repeat loci

DETAILED DESCRIPTION OF THE INVENTION The following definitions are provided to assist in providing a clear and consistent understanding of the scope and detail of the terms: Allelic ladder: a standard size marker consisting of amplified alleles from the locus.
Allele: a genetic variation associated with a segment of DNA, i.
e.
, one of two or more alternate forms of a DNA sequence occupying the same locus.
Biochemical nomenclature: standard biochemical nomenclature is used herein in which the nucleotide bases are designated as adenine (A); thymine (T); guanine (G); and cytosine (C).
Corresponding nucleotides are, for example, deoxyguanosine-5'-triphosphate (dGTP).
DNA polymorphism: the condition in which two or more different nucleotide sequences coexist in the same interbreeding population in a DNA sequence.
Locus (or genetic locus): a specific position on a chromosome.
Alleles of a locus are located at identical sites on homologous chromosomes.
Locus-specific primer: a primer that specifically hybridizes with a portion of the stated locus or its complementary strand, at least for one allele of the locus, and does not hybridize efficiently with other DNA sequences under the conditions used in the amplification method.
Polymerase Chain Reaction (PCR): a technique in which cycles of denaturation, annealing with primer, and extension with DNA polymerase, are used to amplify the number of copies of a target DNA sequence by >10.
sup.
6 times.
The polymerase chain reaction process for amplifying nucleic acid is covered by U.
S.
Pat.
Nos.
4,683,195 and 4,683,202, which are incorporated herein by reference for a description of the process.
Polymorphism information content (PIC): Because matings between two individuals who are both heterozygous but have identical genotypes are often not useful in genetic analysis, PIC was defined to more accurately reflect true informativeness (Botstein et al.
, 1980).
PIC values range from 0 to 1.
0, and are smaller in value than heterozygosities.
For markers that are highly informative (heterozygosities exceeding about 70%), the difference between heterozygosity and PIC is slight