D22S

D22S, often written as D22S or d22s, refers to a family of genetic marker loci located on chromosome 22. The designation comes from historical naming conventions for DNA markers and indicates a position on chromosome 22 rather than a specific gene. D22S loci are typically short tandem repeat (STR) markers used in genetic analysis and identity testing. They are not genes themselves but highly polymorphic DNA sequences that can differentiate individuals and track chromosomal inheritance.

Most D22S markers are analyzed by PCR to determine the length of the repeat region, producing an allelic profile based on fragment size. Because STRs are codominant, both parental alleles can be observed in offspring, which makes D22S markers useful for linkage studies, haplotype construction, and forensic typing. The markers are distributed at various locations along chromosome 22, contributing to a broader map of the chromosome rather than pointing to specific functional elements.

Applications for D22S loci include genetic linkage studies that help locate disease-associated regions on chromosome 22, forensic genetics as part of multi-locus identity panels, and paternity testing when used in combination with other markers. They can assist in constructing chromosomal haplotypes within families and in confirming chromosomal abnormalities through marker analysis in affected individuals.

Notes: D22S markers are part of older genetic maps and were more central before the widespread adoption of single-nucleotide polymorphism (SNP)–based genotyping. Modern panels for forensic and clinical use typically employ a broader set of markers, but D22S loci remain referenced in literature and historical datasets. See also chromosome 22, STR markers, genetic mapping.