Agne, let me post what FamilyTreeDNA says about mtDNA. The boldface-underline is mine:
That means the people with whom you match could have common relatives older than 500 years. In other words, mtDNA by itself is generally not useful for finding relatives.
Bob Kosovsky, New York City, seeking any and all permutations/locations of:
KASOVSKI/Y, KASOWSKI/Y, KOSOFSKY, KOSOVSKY, KOSOWSKY, KOSOW, KOSSOVE, etc.
Slutsk: DAVIDSON, GELFAND (also Sioux City, Iowa)
Klodawa: JARET, JARETSKY, JARECKI, KOLSKY/I; Przedecz: PIFKO, PIWKO