Table 2.

Types of microsatellite alterations in mtDNA

Microsatellite	No. of dinucleotide tracts with additions or deletions of base pairs
	−22	−20	−14	−8	−4	−2	0	+2	Total
(AT)16 (+1 frame)	1						24*		25
(AT)16 (+2 frame)		1	1	3		17	1†		23
(GT)16 (+1 frame)					15		1†	6	22
(GT)16 (+2 frame)			1			32			33

Tracts in independent Arg⁺ revertants were examined by PCR or DNA sequence analysis as described in Materials and Methods. 

^*In 14 of these 24 Arg⁺ strains, the reporter genes were sequenced, and 12 had a deletion of one A in a run of three As located about 10 bp downstream of the dinucleotide tract. In 10 additional strains, PCR analysis indicated a 1-bp deletion, but the genes were not sequenced. 

^† No changes were detected within the dinucleotide tract or in the short run of As located downstream of the tract.