Progress and Prospects in Human Genetic Research into Age-Related Hearing Impairment

Table 2

Common human NAT2 alleles (haplotypes) discussed in the previous studies regarding ARHI (modified from Hein, 2006 [41]).

Allele (haplotype)^1	Nucleotide change(s)^2	Amino acid change(s)^3	Catalytic activity^4	Results in the previous ARHI studies
NAT2 * 4	None	None	High	Wild type
NAT2 * 5A	341T>C (rs1801280); 481 C>T	I114T	Low	Negative by Angeli et al. [37], van Eyken et al. [43], Ünal et al. [44], and Bared et al. [38]
NAT2 * 6A	282 C>T; 590 G>A (rs1799930)	R197Q	Low	Negative by Angeli et al. [37]
				Positive by Ünal et al. [44], van Eyken et al. [43], Bared et al. [38]
NAT2 * 6B	590 G>A (rs1799930)	R197Q	Low	Negative by Angeli et al. [37] and Bared et al. [38]
NAT2 * 7A	857 G>A	G286E	Low	Negative by van Eyken et al. [43]
				(NAT2*7A/B combined) Negative by Ünal et al. [44]
NAT2 * 7B	282 C>T; 857 G>A (rs1799931)	G286E	Low	Negative by Bared et al. [38]
NAT2 * 14A	191 G>A (rs1801279)	R64Q	Low	Negative by Ünal et al. [44], Bared et al. [38]
				Data not shown by van Eyken et al. [43]
NAT2 * 14B	191 G>A (rs1801279); 282 C>T	R64Q	Low	Negative by Bared et al. [38]

1Common NAT2 alleles (haplotypes) associated with low catalytic activity and slow acetylator phenotype are bolded.
²Signature SNP for each cluster is shown with underline.
³Amino-acid substitutions that confer reduced NAT2 activities.
Individuals homozygous for alleles indicated by boldface in annotation 1 are slow acetylators.