In human genetics Haplogroup Q1a3a (phylogenetic name) and/or Q-M3 (mutational name) is a Y-chromosome DNA haplogroup (Y-DNA). Haplogroup Q1a3a is a subclade of haplogroup Q. Haplogroup Q1a3a was previously known as haplogroup Q3. In 1996 Dr. Peter Underhill and his colleagues at Stanford University first discovered the indigenous American clade or single nucleotide polymorphism (SNP) that was to become known as Q1a3a/(Q-M3). Later studies completed the genetic bridge by determining that Q-M3 was related Q-M242-bearing populations found predominately in Central Asia. Within the parent Q clade, there are 13 haplogroups marked by 17 SNPs. The "male" Y chromosome is one of the two sex chromosomes in humans. The Y chromosome spans about 58 million base pairs (the building blocks of DNA) and represents about 2 percent of the total DNA in all human cells. The Y chromosome differs from Human mitochondrial DNA haplogroups (mtDNA) in that the majority of the Y chromosome is unique and does not recombine during meiosis. Meaning the historical pattern of mutations can easily be studied.