The Relationship between Intelligence and Mitochondrial DNA Polymorphism at Site of 15925 Base Pairs

Intelligence has a huge influences and is very closely related with human’s life. Because intelligence is indefinable, scholars have specified it through testing tools and named it intelligence quotient (IQ). In measuring IQ, researchers have found that IQ has a wide distribution and tried to find out the reasons by assessing the brain's functional level and environmental and genetic factors. One study reported an association between IQ and mitochondrial DNA (mtDNA) sequence 15,925, and this study investigated the association in Koreans. The number of participants was 57 in the mental retardation group without chromosomal abnormalities and 148 in the normal group, respectively. PCR technique and direct sequencing analysis were used to know participant’s mtDNA sequences. At 15,925 base, all participants had only wild type C and no variant type of m.15,925 C > T. We further studied variants in mtDNA sequences 15,926-15,927. At 15,926 base, the variant type of 15,926 C < T was found in only one case (0.7%) in the control group. At the 15,927 base, variant type of 15,927 G < A was found in 9 cases (6.1%) in the control group and 1 case (1.8%) in the retardation group, respectively. As a result, the polymorphisms of mtDNA sequences at bases 15,925-15,927 had no statistical significance in the Korean control and mental retardation group.