Null value

From ISOGG Wiki

A null value is the term used when a DNA laboratory is unable to determine a value for a short tandem repeat (STR) marker on the Y chromosome. A null value may be caused by missing genetic material, or a single-nucleotide polymorphism (SNP) near the location of the marker. The SNP prevents a value from being detected. SNPs and nulls, like other marker variations, are passed down on the Y-chromosome from father to son. Null values are often characteristic of specific haplogroups or subclades, but can occur independently in many different haplogroups.

List of null projects

• Null 425 project
• Null 439 project
• Null 448 project

Further reading

• A null primer ISOGG newsletter Vol. 1 No. 4 Jun/Jul 2008
• Thomas Krahns' presentation on null alleles from the Family Tree DNA conference in Houston, Texas in 2009 File size 8 mb