the structure and replication of human leukocyte mitochondrial dna ( mtdna ) was investigated in healthy young adult males ( 23 -- 37 years old ) , middle-aged males ( 42 -- 52 years old ) with secondary polycythemia , and elderly males ( 80 -- 89 years old ) who exhibited different degrees of age-related disease syndromes .
C0012634
disease
C0039082
syndromes