Humans differ genetically by 1%

Scientists are now establishing a more accurate database of human genetic variation, after the shocking news late in 2006 that scientists underestimated the amount of genetic difference among humans by a factor of 10!  We humans are now understood to be 99% alike, not 99.9% alike as previously reported.

It turns out that 12% of our genome is involved in copy number variations (CNVs), with 1% of our genome actually different from other people.  CNVs include repeating and deleted sequences of DNA, implying that some people may have more DNA than other people!  These CNVs affect 2,900 genes (360 million genetic bases, or "letters"), including 15% of known disease gene variants.

The CNV variations are in addition to known single base ("letter") differences (SNPs), making a total of 30 million DNA differences among people (1% of the genome).  These include:

• 1.5 million single-letter differences (SNPs)
• 24 million letters of unmatched sequences among people (i.e. unique among human subgroups)
• 3.5 million multi-copy (repeating) sequences
• 1 million letters in inverted sequence