Table 1.

Details of the different types of satellite DNA

	Satellite	Minisatellite (telomeric)	Minisatellite (hypervariable)	Microsatellite
Other names	–	–	Variable number tandem repeats (VNTRs)	Short tandem repeats (STRs)
Size of repeat unit	5 to several hundred bases	Mainly “TTAGGG”' in humans	6 to > 50 bp	1 to 5 bp
Total expansion size	100 kb to several Mb	10–15 kb	100 bp to ∼ 20 kb	10 to ∼100 bp (excluding certain trinucleotide repeats)
Location	Heterochromatin, especially centromeric heterochromatin	All telomeres	Throughout genome, but most clustered in telomeric regions	Distributed almost ubiquitously throughout genome
Biological functions	Unknown (probably none)	Protects chromosome ends, provides means of terminal sequence replication, possible roles in chromosome pairing and cell ageing	Very rare examples of expression, importance unknown. Otherwise unknown (probably none)	Unknown, but may fine tune gene expression. Again trinucleotides are special case. (Contingency genes in prokaryotes)