DYS464 is known to have 4 to 7 alleles (a to d for 4 or a to g for 7).  Previously, the “genotype” is reported.  When the genotype is reported, identical repeats are reported multiple times if that same repeat is present more than once.  For example, someone may be reported as having the following markers for DYS464:

 DYS464a = 17

DYS464 b= 18

DYS464c = 18

DYS464 d = 19

As shown above, the value “18″ is reported twice.  This type of reporting is known as “genotype” reporting.  However, recent policies implemented by the American Association of Blood Banks mandates that all Accredited DNA testing laboratories must report the “phenotype” instead of “genotype” for multi-copy markers, especially if the marker has more than 2 alleles.  Though the requirements of AABB refers to apparent homozygotes detected on autosomal DNA, the interpretation concerns are similar for multicopy alleles on the Y-Chromosome because peak height ratio detection of STR fragment analysis results is not a validated method for copy number detection in the absence of real time PCR and sequencing.  ref:  Guidance for Standards for Relationship Testing Laboratories 8th Edition, 5.3.3.1.

If the phenotype is reported for the above individual, then his results will be shown as follows:

DYS464a =  17

DYS464b = 18 (duplicate repeat values are only reported once when reporting phenotypes, so when reporting by phenotype, “18″ is only reported once)

DYS464c = 19

Phenotype reporting is especially important in cases with more than 2 alleles such as DYS464 which is known to have up to 7 alleles.  For all future cases, only the phenotype will be reported for DYS464.  In 2009, all previous participant’s data will be adjusted to report only phenotype for DYS464 to ensure compatibility between old and new participants.  If you would like us to convert your genotype into phenotype for DYS464 for comparison reasons prior to the 2009 update, please contact us at support@genebase.com. 

Interpreting DYS464 data

Genetic distance:  Regardless of the number of mismatches in DYS464, the genetic distance is always reported as a maximum of 1.  Click on this link to read more about the “Infinite Alleles Method” which is used to calculate genetic distance for DYS464:  http://www.genebase.com/blog/?p=74

Please remember that “genetic distance” is not the same as “mismatching markers”.  Currently, the mismatching markers calculation is not performed using the Infinite Alleles Method and the mismatching marker value may be larger than the genetic distance.