Genome Technology Branch, NHGRI/NIH, Bethesda, MD 20892-9400, USA. nhansen@mail.nih.gov|Genome Technology Branch, NHGRI/NIH, Bethesda, MD 20892-9400, USA. nhansen@mail.nih.gov|Genome Technology Branch, NHGRI/NIH, Bethesda, MD 20892-9400, USA. nhansen@mail.nih.gov|Genome Technology Branch, NHGRI/NIH, Bethesda, MD 20892-9400, USA. nhansen@mail.nih.gov|Genome Technology Branch, NHGRI/NIH, Bethesda, MD 20892-9400, USA. nhansen@mail.nih.gov