Y-chromosomal microsatellite mutation rates: differences in mutation rate between and within loci.
Precise estimates of mutation rates at Y-chromosomal microsatellite STR (short tandem repeat) loci make an important basis for paternity diagnostics and dating of Y chromosome lineage origins. There are indications of considerable locus mutation rate variability between (inter-) and within (intra-) loci. We have studied nine Y-STR loci-DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS385, and DYS388-in 1,766 father-son pairs of confirmed paternity (a total of 15,894 meioses). Five biallelic markers were also analyzed in the fathers-Tat, YAP, 12f2, SRY1532, and 92R7-defining haplogroups 1, 2, 3, 4, 9, and 16, respectively. A total of 36 fragment length mutations were observed: 24 gains (22 single-step, two double-step) and 12 single-step losses. Thus, there was a significant surplus of gains (p=0.045). Overall, the mutation rate was positively correlated to STR repeat length and there was a significant relative excess of losses in long alleles and gains in short alleles (p=0.043). In contrast to the situation in autosomal STR loci and in MSY-1, no noteworthy correlation between mutation rate and the father's age at the child's birth was observed. We observed significant interlocus differences in Y-STR mutation rates (p<0.01). The number of observed mutations ranged from zero in DYS392 to eight in DYS391 and DYS390. We have also demonstrated obvious differences in mutation rates between the haplogroups studied (p=0.024), a phenomenon that is a reflection of the dependence of mutation rate on allele size. Our study has thus demonstrated the necessity of not only locus-specific, but even allele-specific, mutation rate estimates for forensic and population genetic purposes, and provides a considerable basis for such estimates.
Dupuy
B Myhre
BM
Institute of Forensic Medicine, University of Oslo, Rikshospitalet, Oslo, Norway.
Stenersen
M
M
Institute of Forensic Medicine, University of Oslo, Rikshospitalet, Oslo, Norway.
Egeland
T
T
Biostatistics, Rikshospitalet, Oslo, Norway.
Olaisen
B
B
Institute of Forensic Medicine, University of Oslo, Rikshospitalet, Oslo, Norway.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D041322:Chromosomes, Human, Y / Q000235:genetics*; D005220:Fathers; D005819:Genetic Markers / Q000235:genetics*; D006801:Humans; D008297:Male; D008540:Meiosis / Q000235:genetics; D008875:Middle Aged; D018598:Minisatellite Repeats / Q000235:genetics*; D016296:Mutagenesis / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D009679:Nuclear Family
D005819:Genetic Markers