Two broad categories of DNA markers have been used to examine Y chromosome diversity: bi-allelic loci, which exhibit two possible alleles, and multi-allelic loci. Results from typing the lower resolution bi-allelic markers are classified into haplogroups while multi-allelic results are characterized as haplotypes (de Knijff 2000).
Bi-allelic markers include single nucleotide polymorphisms (Y-SNPs) and an Alu element insertion (see Chapter 8). The Y-Alu polymorphism (YAP) was the first discovered Y chromosome bi-allelic marker (Hammer 1994). Bi-allelic markers are sometimes referred to as unique event polymorphisms (UEPs) because of their low mutation rates (~10-8 per generation). Approximately 250 bi-allelic Y chromosome markers have been characterized (Y Chromosome Consortium 2002, Butler 2003).
Y chromosome multi-allelic markers include two minisatellites and over 200 short tandem repeat (Y-STR) markers (Butler 2003, Kayser et al. 2004). These multi-allelic loci can be used to differentiate Y chromosome haplotypes with fairly high resolution due to their higher mutation rates. Minisatellite loci have mutation rates as high as 6-11% per generation (Jobling et al. 1999) while the average mutation rate for Y-STRs is ~0.2% per generation (Kayer et al. 2000, Dupuy et al. 2004).
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This book discusses the futility of curing stammering by common means. It traces various attempts at curing stammering in the past and how wasteful these attempt were, until he discovered a simple program to cure it. The book presents the life of Benjamin Nathaniel Bogue and his struggles with the handicap. Bogue devotes a great deal of text to explain the handicap of stammering, its effects on the body and psychology of the sufferer, and its cure.