A curated public database designed to represent, store, and analyze the divergent forms of data underlying HIV drug resistance.

NRTI Resistance Notes

Position	Cons	AA	Comment
41	M	L	M41L usually occurs with T215Y. Together these mutations confer intermediate-to-high level resistance to AZT and d4T and a lower level of resistance to ddI, ABC, and TDF.
41	M	NOT L	M41L usually occurs with T215Y. Together these mutations confer intermediate-to-high level resistance to AZT and d4T and a lower level of resistance to ddI, ABC, and TDF. $listMutsIn{41(NOT L)} is a highly unusual mutation at this position.
44	E	AD	E44A/D occur in patients receiving multiple NRTIs. E44D causes low-level resistance to 3TC and probably to each of the other NRTIs when present with V118I or one or more TAMs.
62	A	V	A62V is associated with multinucleoside resistance caused by Q151M; its effect in the absence of Q151M is not known.
62	A	NOT V	A62V is associated with multinucleoside resistance caused by Q151M; its effect in the absence of Q151M is not known. $listMutsIn{62(NOT V)} is a highly unusual mutation at this position.
65	K	N	K65R causes intermediate resistance to ddI, ABC, 3TC, FTC, and TDF, and low-level resistance to d4T. K65R causes AZT hypersusceptibility. K65N is an extremely rare mutation that may have a similar effect.
65	K	R	K65R causes intermediate resistance to ddI, ABC, 3TC, FTC, and TDF, and low-level resistance to d4T. K65R causes AZT hypersusceptibility.
65	K	NOT NR	K65R/N are known NRTI-resistance mutations. $listMutsIn{65(NOT NR)} is a highly unusual mutation at this position.
67	D	EG	D67N contributes some degree of resistance to each of the NRTIs except 3TC and FTC. It usually occurs with mutations at positions 70 or 215. D67E/G occur in heavily treated patients but their precise effect on NRTI susceptibility is not known.
67	D	N	D67N contributes some degree of resistance to each of the NRTIs except 3TC and FTC. It usually occurs with mutations at positions 70 or 215.
67	D	d	Amino acid deletions (d) in this region occur uncommonly. They occur in combination with other NRTI mutations and contribute decreased susceptibility to each of the NRTIs.
67	D	NOT EGNd	D67N contributes some degree of resistance to each of the NRTIs except 3TC and FTC. It usually occurs with mutations at positions 70 or 215. D67E/G occur in heavily treated patients but their precise effect on NRTI susceptibility is not known. $listMutsIn{67(NOT EGNd)} is a highly unusual mutation at this position.
69	T	D	T69D, a mutation originally identified for its role in causing ddC reistance, is associated with decreased susceptibility to ddI and d4T.
69	T	G	T69G occurs in isolates with a deletion at position 67 but its effect on NRTI susceptibility is not known.
69	T	NSAI	T69N/S/A/I are NRTI-selected mutations but their effect on NRTI susceptibility is not known.
69	T	i	Amino acid insertions (i) at this position occur in about 1%-2% of heavily treated persons. Together with TAMs, they confer high-level resistance to each of the NRTIs. Most susceptibility data are available for double amino acid insertions. However, insertions of 1 or >2 amino acids also occur.
69	T	NOT ADGINSi	T69D/N/S/G/A/I are NRTI-selected mutations. $listMutsIn{69(NOT ADGINSi)} is a highly unusual mutation at this position.
70	K	EG	K70E/G reduces TDF, ABC, DDI, and to a lesser extent 3TC and FTC susceptibility.
70	K	R	K70R causes low-level AZT, d4T, and possibly TDF resistance.
70	K	NOT EGR	K70R causes low-level AZT, d4T, and possibly TDF resistance. K70E/G reduces TDF, ABC, DDI, and to a lesser extent 3TC and FTC susceptibility. $listMutsIn{70(NOT EGR)} is an unusual mutation at this position.
74	L	I	L74V reduces susceptibility to ddI and ABC susceptibility and increases susceptibility AZT and TDF.
74	L	V	L74V reduces susceptibility to ddI and ABC susceptibility and increases susceptibility AZT and TDF. L74I appears to have a similar effect but may not increase AZT and TDF susceptibility.
74	L	NOT IV	L74V reduces susceptibility to ddI and ABC susceptibility and increases susceptibility AZT and TDF. L74I appears to have a similar effect but may not increase AZT and TDF susceptibility. $listMutsIn{74(NOT IV)} is a highly unusual mutation at this position.
75	V	I	V75I increases multinucleoside resistance caused by Q151M when present with F77L and F116Y; its effect in the absence of Q151M is not known.
75	V	L	V75L does not appear to be associated with reduced NRTI susceptibility.
75	V	TMAS	V75T/M/A/S reduce d4T and possibly ddI susceptibility.
75	V	NOT AIMSTL	V75M/T/A/S/I are NRTI-selected mutations. $listMutsIn{75(NOT AIMSTL)} is a highly unusual mutation at this position.
77	F	L	F77L increases multinucleoside resistance caused by Q151M when present with V75I or F116Y; its effect in the absence of Q151M is not known.
77	F	NOT L	F77L increases multinucleoside resistance caused by Q151M when present with V75I or F116Y. $listMutsIn{77(NOT L)} is a highly unusual mutation at this position
115	Y	F	Y115F causes intermediate resistance to ABC and low-level resistance to TDF.
115	Y	NOT F	Y115F causes intermediate resistance to ABC and low-level resistance to TDF. $listMutsIn{115(NOT F)} is a highly unusual mutation at this position.
116	F	Y	F116Y increases multinucleoside resistance caused by Q151M when present with F77L or V75I; its effect in the absence of Q151M is not known.
116	F	NOT Y	F116Y increases multinucleoside resistance caused by Q151M when present with F77L or V75I; its effect in the absence of Q151M is not known. $listMutsIn{116(NOT Y)} is a highly unusual mutation at this position.
118	V	I	V118I occurs in ~2% of untreated persons and with increased frequency in persons receiving multiple NRTIs. It causes low-level resistance to 3TC and possibly to other NRTIs when present with E44A/D and/or one or more TAMs.
118	V	NOT I	$listMutsIn{V118(NOT I)} is a highly unusual mutation at this position.
151	Q	L	By itself, Q151M causes intermediate-to-high level resistance to AZT, ddI, d4T, and ABC; and low-level resistance to TDF. With changes at the associated positions 75, 77, and 116, Q151M confers high-level resistance to AZT, ddI, d4T, and ABC; intermediate resistance to TDF, and low-level resistance to 3TC and FTC. Q151L is a rarely observed transitional mutation that may precede the emergence of the Q151M.
151	Q	M	By itself, Q151M causes intermediate-to-high level resistance to AZT, ddI, d4T, and ABC; and low-level resistance to TDF. With changes at the associated positions 75, 77, and 116, Q151M confers high-level resistance to AZT, ddI, d4T, and ABC; intermediate resistance to TDF, and low-level resistance to 3TC and FTC.
151	Q	NOT LM	By itself, Q151M causes intermediate-to-high level resistance to AZT, ddI, d4T, and ABC; and low-level resistance to TDF. With changes at the associated positions 75, 77, and 116, Q151M confers high-level resistance to AZT, ddI, d4T, and ABC; intermediate resistance to TDF, and low-level resistance to 3TC and FTC. $listMutsIn{151(NOT LM)} is a highly unusual mutation at this position.
184	M	VI	M184V/I cause high-level in vitro resistance to 3TC and FTC and low-level in vitro resistance to ddI and ABC. M184V/I increase susceptibility to AZT, TDF, and d4T.
184	M	NOT IV	M184V/I cause high-level in vitro resistance to 3TC and FTC and low-level in vitro resistance to ddI and ABC. M184V/I increase susceptibility to AZT, TDF, and d4T. $listMutsIn{184(NOT IV)} is a highly unusual mutation at this position.
210	L	FS	L210W contributes resistance to each of the NRTIs except 3TC and FTC. It usually occurs with the mutations M41L and T215Y. L210F/S occur rarely and are of unknown significance.
210	L	W	L210W contributes resistance to each of the NRTIs except 3TC and FTC. It usually occurs with the mutations M41L and T215Y.
210	L	NOT FSW	L210W contributes resistance to each of the NRTIs except 3TC and FTC. It usually occurs with the mutations M41L and T215Y. $listMutsIn{210(NOT FSW)} is a highly unusual mutation at this position.
215	T	F	T215F causes AZT and D4T resistance and reduces susceptibility to ABC, ddI, and to a lesser extent TDF.
215	T	SCDEIV	T215S/C/D/E/I/V are transitions between wild type and the mutations Y and F. Most do not reduce NRTI susceptibility but their presence may suggests that T215Y or F may also be present.
215	T	Y	T215Y causes AZT and D4T resistance and reduces susceptibility to ABC, ddI, and TDF particularly when it occurs in combination with M41L and L210W.
215	T	NOT CDEFISVY	T215Y causes AZT and D4T resistance and reduces susceptibility to ABC, ddI, and TDF particularly when it occurs in combination with M41L and L210W. T215S/C/D/E/I/V are transitions between wild type and the mutations Y and F. Most do not reduce NRTI susceptibility but their presence may suggests that T215Y or F may also be present. $listMutsIn{215(NOT CDEFISVY)} is a highly unusual mutation at this position.
219	K	EQ	K219Q/E decrease AZT and probably d4T susceptibility when present with K70R or T215Y/F but have little if any effect on the remaining NRTIs.
219	K	NR	K219N/R occur commonly in heavily NRTI-treated patients. Their effect on NRTI susceptibility is uncertain.
219	K	WDH	K219W/H/D are uncommon NRTI-selected mutations at this position.
219	K	NOT ENQRWDH	K219Q/E/N/R/W/D/H are NNRTI-associated mutations. $listMutsIn{219(NOT ENQRWDH)} is an unusual mutation at this position.
348	N	I	N348I causes low-level reductions in AZT and NVP susceptibility.
348	N	NOT I	N348I causes low-level reductions in AZT and NVP susceptibility. $listMutsIn{348(NOT I)} is an unusual mutation at this position.