ABCMdb

ABCC8 p.Leu582Val

Predicted by SNAP2:	A: D (53%), C: N (57%), D: D (85%), E: D (80%), F: D (59%), G: D (75%), H: D (75%), I: N (57%), K: D (80%), M: D (53%), N: D (80%), P: D (85%), Q: D (75%), R: D (80%), S: D (71%), T: D (59%), V: N (78%), W: D (63%), Y: D (59%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, M: N, N: D, P: D, Q: D, R: D, S: D, T: D, V: N, W: D, Y: D,

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[hide] Mutations in the ABCC8 gene encoding the SUR1 subu... Diabetes Obes Metab. 2007 Nov;9 Suppl 2:28-39. Patch AM, Flanagan SE, Boustred C, Hattersley AT, Ellard S
Mutations in the ABCC8 gene encoding the SUR1 subunit of the KATP channel cause transient neonatal diabetes, permanent neonatal diabetes or permanent diabetes diagnosed outside the neonatal period.
Diabetes Obes Metab. 2007 Nov;9 Suppl 2:28-39., [PMID:17919176]

Abstract [show]
AIM: Mutations in the ABCC8 gene encoding the SUR1 subunit of the pancreatic ATP-sensitive potassium channel cause permanent neonatal diabetes mellitus (PNDM) and transient neonatal diabetes mellitus (TNDM). We reviewed the existing literature, extended the number of cases and explored genotype-phenotype correlations. METHODS: Mutations were identified by sequencing in patients diagnosed with diabetes before 6 months without a KCNJ11 mutation. RESULTS: We identified ABCC8 mutations in an additional nine probands (including five novel mutations L135P, R306H, R1314H, L438F and M1290V), bringing the total of reported families to 48. Both dominant and recessive mutations were observed with recessive inheritance more common in PNDM than TNDM (9 vs. 1; p < 0.01). The remainder of the PNDM probands (n = 12) had de novo mutations. Seventeen of twenty-five children with TNDM inherited their heterozygous mutation from a parent. Nine of these parents had permanent diabetes (median age at diagnosis: 27.5 years, range: 13-35 years). Recurrent mutations of residues R1183 and R1380 were found only in TNDM probands and dominant mutations causing PNDM clustered within exons 2-5. CONCLUSIONS: ABCC8 mutations cause PNDM, TNDM or permanent diabetes diagnosed outside the neonatal period. There is some evidence that the location of the mutation is correlated with the clinical phenotype.

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86 Nine mutations were observed in more than one proband; R1183W (c.3547C>T) was identified in five probands, R1380C (c.4138C>T) in three probands and the remainder; F132L (c.394T>C), D209E (c.627C>A), T229I (c.686C>T), L582V (c.1744C>G), R826W (c.2476C>T), R1183Q (c.3548G>A) and R1380L (c.4139G>T) were each observed in two probands. Login to comment
161 Affected probands and family members can be separated into three distinct groups based T229I/T229I ABCC8 mutations Transient Neonatal Diabetes Mellitus Recessive homozygous mutations R826W (2) H1024Y R1183Q (2) R1183W (5) R1314H R1380C (3) R1380H R1380L (2) D209E D212I D212N R306H V324M C435R L451P L582V (2) Dominant heterozygous mutations Permanent Neonatal Diabetes Mellitus E382K/E382K A1185E/A1185E Mosaic N72S Recessive homozygous or mosaic mutations P45L/G1401R E208K/Y263D T229I/V1523L L438F/M1290V P207S/c.536del4 E1327K+V1523A/ c.1327ins10 Recessive compound heterozygous mutations 1K Dominant heterozygous mutations D209E Q21 L213R L225P(2) I1425V V86A V86G F132L (2) F132V L135P Fig. 2 A diagram illustrating the inheritance of ABCC8 mutations in probands with permanent and transient forms of neonatal diabetes. Login to comment
163 Permanent Neonatal Diabetes Mellitus Transient Neonatal Diabetes Mellitus 1 5 10 15 20 25 30 35 39 N72S V86A V86G F132L F132V L135PP45L P207S E208K D209E Q211K L213R L225P T229I Y263D D209E D212I D212N T229I R306H V324M L438F L451P E382K R826W R1183W R1183Q A1185E E1327K R1314H M1290V R1380C R1380H R1380L G1401R V1523A V1523L H1024YC435R L582V I1425V Fig. 3 The location of missense mutations causing neonatal diabetes within the coding sequence of ABCC8. Login to comment
176 No neurological features were reported in R1183W/Q A1185E E1327K G1401R V1523A/L NBD1 NBD2 outside membrane inside P45L N72S F132L/V L135P P207S E208K D209E Q211K D212I/N L213R L225P T229I Y263D E382K V86A/G L438F C435R R1380C/H/L L451P R826W TMD0 TMD1 TMD2 R306H V324M L582V H1024Y I1425V R1314H M1290V Fig. 4 A schematic of the membrane topologies of SUR1 showing the location of the ABCC8 missense mutations causing neonatal diabetes. Login to comment

[hide] Permanent neonatal diabetes due to activating muta... Rev Endocr Metab Disord. 2010 Sep;11(3):193-8. Edghill EL, Flanagan SE, Ellard S
Permanent neonatal diabetes due to activating mutations in ABCC8 and KCNJ11.
Rev Endocr Metab Disord. 2010 Sep;11(3):193-8., [PMID:20922570]

Abstract [show]
The ATP-sensitive potassium (K(ATP)) channel is composed of two subunits SUR1 and Kir6.2. The channel is key for glucose stimulated insulin release from the pancreatic beta cell. Activating mutations have been identified in the genes encoding these subunits, ABCC8 and KCNJ11, and account for approximately 40% of permanent neonatal diabetes cases. The majority of patients with a K(ATP) mutation present with isolated diabetes however some have presented with the Developmental delay, Epilepsy and Neonatal Diabetes syndrome. This review focuses on mutations in the K(ATP) channel which result in permanent neonatal diabetes, we review the clinical and functional effects as well as the implications for treatment.

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85 One of the most notable R1183W/Q A1185E E1327K G1401R V1523A/L V1524M R1531A NBD1 NBD2 outside membrane inside P45L N72S F132L/V L135P P207S E208K D209E Q211K D212I/N L213R L225P T229I Y263D A269D/N E382K V86A/G R1380C/H/L C435R L438F M1290V L451P R826W R1314H TMD0 TMD1 TMD2 R306H V324M L582V H1024Y I1425V A90V Y356C R521Q N1123D R1153G T1043TfsX74 Fig. 3 Schematic representation of 50 ABCC8 mutations which cause neonatal diabetes. Login to comment

[hide] Review. SUR1: a unique ATP-binding cassette protei... Philos Trans R Soc Lond B Biol Sci. 2009 Jan 27;364(1514):257-67. Aittoniemi J, Fotinou C, Craig TJ, de Wet H, Proks P, Ashcroft FM
Review. SUR1: a unique ATP-binding cassette protein that functions as an ion channel regulator.
Philos Trans R Soc Lond B Biol Sci. 2009 Jan 27;364(1514):257-67., [PMID:18990670]

Abstract [show]
SUR1 is an ATP-binding cassette (ABC) transporter with a novel function. In contrast to other ABC proteins, it serves as the regulatory subunit of an ion channel. The ATP-sensitive (KATP) channel is an octameric complex of four pore-forming Kir6.2 subunits and four regulatory SUR1 subunits, and it links cell metabolism to electrical activity in many cell types. ATPase activity at the nucleotide-binding domains of SUR results in an increase in KATP channel open probability. Conversely, ATP binding to Kir6.2 closes the channel. Metabolic regulation is achieved by the balance between these two opposing effects. Precisely how SUR1 talks to Kir6.2 remains unclear, but recent studies have identified some residues and domains that are involved in both physical and functional interactions between the two proteins. The importance of these interactions is exemplified by the fact that impaired regulation of Kir6.2 by SUR1 results in human disease, with loss-of-function SUR1 mutations causing congenital hyperinsulinism and gain-of-function SUR1 mutations leading to neonatal diabetes. This paper reviews recent data on the regulation of Kir6.2 by SUR1 and considers the molecular mechanisms by which SUR1 mutations produce disease.

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204 (a) (b) P45L N72S F132L NH2 A90V V86G COOHL135P exoplasmic cytoplasmic Walker A Walker A linker Walker B linker Walker B V324M E382K C435R L438F L582V R826W H1023Y N1122D R1183Q A1185E R1314H E1327K R1380 L I1425V V1524 L P207S E208K Q211K D212I/N L225P T229I Y263D A269D R306H D209E L213R TMD0 TMD1 TMD2 NBD1 NBD2 CL3 linker site 1 site 2 NBD1 NBD2 R826W R1380 L E1327K I1425V V1524 L Figure 5. Login to comment
207 (a) (b) P45L N72S F132L NH2 A90V V86G COOH L135P exoplasmic cytoplasmic Walker A Walker A linker Walker B linker Walker B V324M E382K C435R L438F L582V R826W H1023Y N1122D R1183Q A1185E R1314H E1327K R1380 L I1425V V1524 L P207S E208K Q211K D212I/N L225P T229I Y263D A269D R306H D209E L213R TMD0 TMD1 TMD2 NBD1 NBD2 CL3 linker site 1 site 2 NBD1 NBD2 R826W R1380 L E1327K I1425V V1524 L Figure 5. Login to comment

[hide] Clinical and metabolic features of adult-onset dia... Diabetes Care. 2012 Feb;35(2):248-51. Epub 2011 Dec 30. Riveline JP, Rousseau E, Reznik Y, Fetita S, Philippe J, Dechaume A, Hartemann A, Polak M, Petit C, Charpentier G, Gautier JF, Froguel P, Vaxillaire M
Clinical and metabolic features of adult-onset diabetes caused by ABCC8 mutations.
Diabetes Care. 2012 Feb;35(2):248-51. Epub 2011 Dec 30., [PMID:22210575]

Abstract [show]
OBJECTIVE: Gain-of-function ABCC8/sulfonylurea (SU) receptor 1 mutations cause neonatal diabetes mellitus (NDM) or late-onset diabetes in adult relatives. Given the effectiveness of SU treatment in ABCC8-NDM patients, we further characterized late-onset ABCC8-associated diabetes. RESEARCH DESIGN AND METHODS: Seven adult subjects from three NDM families and one family with type 2 diabetes were studied. Insulin secretion and insulin sensitivity were assessed using clamp techniques. We screened 139 type 2 diabetic patients who were well controlled by SU for ABCC8 mutations. RESULTS: ABCC8 mutation carriers exhibited glucose intolerance, frank diabetes, or insulin-requiring diabetes since diagnosis. HbA(1c) improved in five SU-treated patients. Insulin secretion capacity was impaired in three patients compared with adult control subjects but was restored after a 4-week SU trial in two patients. Cohort screening revealed four SU-treated patients with ABCC8 mutations, two of which are likely causal. CONCLUSIONS: Although of rare occurrence, recognition of adult-onset ABCC8-associated diabetes may help in targeting patients for SU therapy.

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49 A pathogenic role for three mutations (C435R, L582V, and R1380H) is very likely, because NDM was diagnosed in family relatives (this study) or reported by other studies (2,4,11). Login to comment
57 A pathogenic role for three mutations (C435R, L582V, and R1380H) is very likely, because NDM was diagnosed in family relatives (this study) or reported by other studies (2,4,11). Login to comment

[hide] Activating mutations in the ABCC8 gene in neonatal... N Engl J Med. 2006 Aug 3;355(5):456-66. Babenko AP, Polak M, Cave H, Busiah K, Czernichow P, Scharfmann R, Bryan J, Aguilar-Bryan L, Vaxillaire M, Froguel P
Activating mutations in the ABCC8 gene in neonatal diabetes mellitus.
N Engl J Med. 2006 Aug 3;355(5):456-66., [PMID:16885549]

Abstract [show]
BACKGROUND: The ATP-sensitive potassium (K(ATP)) channel, composed of the beta-cell proteins sulfonylurea receptor (SUR1) and inward-rectifying potassium channel subunit Kir6.2, is a key regulator of insulin release. It is inhibited by the binding of adenine nucleotides to subunit Kir6.2, which closes the channel, and activated by nucleotide binding or hydrolysis on SUR1, which opens the channel. The balance of these opposing actions determines the low open-channel probability, P(O), which controls the excitability of pancreatic beta cells. We hypothesized that activating mutations in ABCC8, which encodes SUR1, cause neonatal diabetes. METHODS: We screened the 39 exons of ABCC8 in 34 patients with permanent or transient neonatal diabetes of unknown origin. We assayed the electrophysiologic activity of mutant and wild-type K(ATP) channels. RESULTS: We identified seven missense mutations in nine patients. Four mutations were familial and showed vertical transmission with neonatal and adult-onset diabetes; the remaining mutations were not transmitted and not found in more than 300 patients without diabetes or with early-onset diabetes of similar genetic background. Mutant channels in intact cells and in physiologic concentrations of magnesium ATP had a markedly higher P(O) than did wild-type channels. These overactive channels remained sensitive to sulfonylurea, and treatment with sulfonylureas resulted in euglycemia. CONCLUSIONS: Dominant mutations in ABCC8 accounted for 12 percent of cases of neonatal diabetes in the study group. Diabetes results from a newly discovered mechanism whereby the basal magnesium-nucleotide-dependent stimulatory action of SUR1 on the Kir pore is elevated and blockade by sulfonylureas is preserved.

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43 A homology model26 of the human SUR1 core was used to map the mutant residues.27 Results ABCC8 Mutations in Patients with Permanent or Transient Neonatal Diabetes We identified seven heterozygous ABCC8 mutations in 9 of 34 patients with neonatal diabetes: L213R and I1424V in 2 with permanent neonatal diabetes and C435R, L582V, H1023Y, R1182Q, and R1379C in patients with transient neonatal diabetes. Login to comment
48 The L213R, H1023Y, and I1424V were noninherited mutations, as were the L582V and R1379C mutations in one family each. Login to comment
49 The L582V and R1397C mutations were also inherited in one family each, as were the C435R and R1182Q mutations. Login to comment
67 After identification of the mutations in the patients with permanent neonatal diabetes, glyburide therapy was initiated and found to be successful and insulin was discontinued after 2 days in the proband from Family 12 and after 15 days in the proband from A Permanent Neonatal Diabetes B Transient Neonatal Diabetes NN NN NN NN NN NN NN NNNM NM NM NM NM NMNM NM NM* NM* NA NA NA NA NANANANANA NA NA NA NA Family 12 (L213R) NNNN NM Family 36 (L582V) 16 NN NN NNNM NMNM Family 28 (H1023Y) Family 34 (R1182Q) Family 16 (L582V) Family 17 (R1379C) Family 16 (I1424V) I II III I II III IV V 1 1 2 1 2 3 4 5 2 1 2 1 2 1 2 1 2 3 4 5 6 7 3 1 4 6 NNNN NN NNNM NMNM* Family 13 (C435R) Family 19 (R1379C) Transient Neonatal Diabetes Figure 1. Login to comment
42 A homology model26 of the human SUR1 core was used to map the mutant residues.27 Results ABCC8 Mutations in Patients with Permanent or Transient Neonatal Diabetes We identified seven heterozygous ABCC8 mutations in 9 of 34 patients with neonatal diabetes: L213R and I1424V in 2 with permanent neonatal diabetes and C435R, L582V, H1023Y, R1182Q, and R1379C in patients with transient neonatal diabetes. Login to comment
47 The L213R, H1023Y, and I1424V were noninherited mutations, as were the L582V and R1379C mutations in one family each. Login to comment
66 After identification of the mutations in the patients with permanent neonatal diabetes, glyburide therapy was initiated and found to be successful and insulin was discontinued after 2 days in the proband from Family 12 and after 15 days in the proband from A Permanent Neonatal Diabetes B Transient Neonatal Diabetes NN NN NN NN NN NN NN NN NM NM NM NM NM NM NM NM NM* NM* NA NA NA NA NA NA NA NA NA NA NA NA NA Family 12 (L213R) NN NN NM Family 36 (L582V) 16 NN NN NN NM NM NM Family 28 (H1023Y) Family 34 (R1182Q) Family 16 (L582V) Family 17 (R1379C) Family 16 (I1424V) I II III I II III IV V 1 1 2 1 2 3 4 5 2 1 2 1 2 1 2 1 2 3 4 5 6 7 3 1 4 6 NN NN NN NN NM NM NM* Family 13 (C435R) Family 19 (R1379C) Transient Neonatal Diabetes Figure 1. Login to comment
92 Mutation Sex Wk of Gestation Birth Weight At Diagnosis At Metabolic Testing Current Treatment Age Weight Presentation Glucose Age Height Weight Insulin g (percentile) days g mmol/liter yr cm (SD)ߤ kg (percentile) U/kg/day Permanent neonatal diabetes 12 L213R Male 41 3065 (22) 125 5320 Polyuria, polydipsia 28.6 4.75 107.5 (0) 17 (50) 0.12 Glb, 10 mg/day 16 I1424V Male 40 3080 (25) 33 3360 Ketoacidosis 66 16.5 178 (+0.9) 69 (85) 0.88 Glb, 15 mg/day Transient neonatal diabetes 13 C435R Male 40 3040 (25) 32 3575 Polyuria, polydipsia 44.5 4.75 108.8 (+0.5) 17.5 (75) 16 L582V Male 40 3350 (50) 15 3210 Polyuria, polydipsia 51.4 5.25 117 (+1.9) 18.4 (50) 17 R1379C Female 40 2050 (<3) 3 2100 Hyperglycemia 6.9 5.25 114.5 (+1.6) 19.5 (82) 19 R1379C Female 40 2330 (<3) 60 4900 Polyuria, polydipsia 22 15.7 158 (-0.8) 54 (70) 1.2 Glb, 10 mg/day 28 H1023Y Male 40 3400 (55) 21 NA Ketoacidosis 37.8 16 180 (+1.2) 59.5 (60) 0.5 Glp, 10 mg/day 34 R1182Q Male 34 1830 (8) 4 1680 Hyperglycemia 13.6 2 82 (-1.5) 10.3 (8) 36 L582V Male 40 3570 (67) 74 6100 Polyuria, polydipsia 34 1.8 92 (+2) 14 (90) * Glb denotes glyburide, NA not available, and Glp glipizide. Login to comment

[hide] New ABCC8 mutations in relapsing neonatal diabetes... Diabetes. 2007 Jun;56(6):1737-41. Epub 2007 Mar 27. Vaxillaire M, Dechaume A, Busiah K, Cave H, Pereira S, Scharfmann R, de Nanclares GP, Castano L, Froguel P, Polak M
New ABCC8 mutations in relapsing neonatal diabetes and clinical features.
Diabetes. 2007 Jun;56(6):1737-41. Epub 2007 Mar 27., [PMID:17389331]

Abstract [show]
Activating mutations in the ABCC8 gene that encodes the sulfonylurea receptor 1 (SUR1) regulatory subunit of the pancreatic islet ATP-sensitive K(+) channel (K(ATP) channel) cause both permanent and transient neonatal diabetes. Recently, we have described the novel mechanism where basal Mg-nucleotide-dependent stimulatory action of SUR1 on the Kir6.2 pore is increased. In our present study, we identified six new heterozygous ABCC8 mutations, mainly in patients presenting the transient form of neonatal diabetes (six of eight), with a median duration of initial insulin therapy of 17 months (range 0.5-38.0). Most of these mutations map to key functional domains of SUR1. Whereas Kir6.2 mutations are a common cause of permanent neonatal diabetes and in a few cases associate with the DEND (developmental delay, epilepsy, and neonatal diabetes) syndrome, SUR1 mutations are more frequent in transient (52%) compared with permanent (14%) neonatal diabetes cases screened for ABCC8 in our series. Although ketoacidosis is frequent at presentation, SUR1 mutations associate mainly with transient hyperglycemia, with possible recurrence later in life. One-half of the SUR1 neonatal diabetic patients presented with de novo mutations. In some familial cases, diabetes is not always present in the adult carriers of SUR1 mutations, supporting variability in their clinical expressivity that remains to be fully explained.

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34 Eleven patients are of French origin, four are Spanish (16), and one (KS-L582V) (Table 1) is from Turkey. Login to comment
39 The two other mutations, L582V (c.1744CϾG) and R1182Q (c.3545GϾA), had been previously described by our group in three independent families with TND cases (13). Login to comment
50 In the families with E208K, L582V, and R825W mutations, the fathers carried the mutation in the heterozygous state, whereas the A269D mutation in the NJ family was inherited from the mother (Table 1). Login to comment
51 The R1182Q and V1523M mutations were not identified in either parent, consistent with de novo mutations. Login to comment
66 Probands SGM-E208K, KS-L582V, and LM-R825W have a mutation inherited from their fathers and proband NJ-A269D from her mother (Table 1). Login to comment
67 In families with the L582V, R825W, and A269D mutations, glucose tolerance tests were performed in the fathers and mother, who were found to be free from diabetes. Login to comment
68 However, the father of KS-L582V has an A1C just above the upper limit of normal, which may suggest minimal glucose disposal disturbances. Login to comment
69 In the case of the father of SGM-E208K, glucose intolerance was documented during the oral glucose tolerance test. Login to comment
77 In the ND-SUR1 patients, an apparently mild phenotype, i.e., without neurological features, is observed in the TND families, except in a few cases presenting with PND (13) TABLE1 ClinicalfeaturesinneonataldiabeticpatientsscreenedpositiveforABCC8mutations Patient SGMGKKSLMCNCDDLNJ MutationE208KV324ML582VR825WR1182QR1379HV1523MA269D SexFemaleMaleMaleFemaleFemaleMaleMaleFemale TypeofdiabetesTNDTNDTNDTNDTNDTNDPND Notyet known Atbirth Weight(g/percentile)1,790/321,660/Ͻ33,250/282,300/Ͻ32,930/103,150/432,710/312,390/Ͻ3 Gestationweek33.53739394138.53739 Atpresentation Age(days)1112361013426766 Weight(g)1,7904,2904,3002,5203,0003,6903,6605,100 PresentationGlucose monitoring KetoacidosisKetoacidosisGlucose monitoring WeightlossKetoacidosisKetoacidosisKetoaciduria Glucose(mmol/l)12.424.160.516.824.164.23627.5 Autoantibodies00000000 Insulindose(units⅐kg-1 ⅐day-1 )0.1012.400.300.720.502.500.72 PancreasultrasonographyNANANNNNNN Currentstatus Age(months)712728134833188.7 Height(cm/SD)63/-1.6134.5/-0.790.2/0.672.5/-0.4101.2/0.296/184/1.370/0.8 Weight(kg/percentile)6.15/323.6/Ͻ313.5/759.62/5614.9/5017.5/Ͼ9711/318.52/50 Diabetes(yes[ϩ],no[-])-ϩ(9)*----ϩϩ Insulindose(units⅐kg-1 ⅐day-1 )00†00000.600.62 A1Catlastexamination(%)4.56.05.15.05.45.05.58.9 Neurologicalfeatures MuscleweaknessNoNoNoNoNoNoNoNo MotordevelopmentaldelayNoNoNoNoNoNoNoNo EpilepsyNoNoNoNoNoNoNoNo MentaldevelopmentaldelayNoNoNoNoNoNoNoNo SpeechdevelopmentaldelayNoYesNoNoNoYesNoNo DysmorphicfeaturesNoNoNoNoNoNoNoNo OtherfeaturesNoNoNoNoNoHyperkinesia, troubleof feeding behavior NoHypotonia ParentwithamutationFatherNone‡FatherFatherNoneNone‡NoneMother Glucosetolerance§IGT-NN---N Ageatexamination(year)41-3129---25 A1Catlastexamination(%)¶5.4-6.1NA---5.2 BMIatlastexamination(kg/m2 )27-2422---NA *Ageatrelapse,inyear.†PatientGK-V324Mwassuccessfullyswitchedtoglibenclamide(gliburide)attheageof9.5years(currentdose2.5mg/day;weight25kg).‡Onlythemotherwas screenedforthemutation;thefatherofGK-V324Mdied,andnoinformationisavailableonthebiologicalfatherofCD-R1379H.§Assessedbyanoralglucosetolerancetest.¶Upperlimit ofnormalvaluesforA1C:5.6%.IGT,impairedglucosetolerance;N,normal;NA,notavailable. Login to comment
84 We believe that those mutations (A269D, L582V, and R825W) are not polymorphisms, as they were shown to be absent from a large number of euglycemic subjects. Login to comment
85 Moreover, one of these mutations, L582V, has been shown to cosegregate with diabetes in one previously published family (13). Login to comment
35 Eleven patients are of French origin, four are Spanish (16), and one (KS-L582V) (Table 1) is from Turkey. Login to comment
40 The two other mutations, L582V (c.1744Cb0e;G) and R1182Q (c.3545Gb0e;A), had been previously described by our group in three independent families with TND cases (13). Login to comment
87 Strikingly, some of the parents of the probands (two fathers and one mother) are carriers of an ABCC8 mutation likely to be responsible for neonatal diabetes in their children and, despite this, have normal glucose tolerance as shown in an oral glucose tolerance test. We believe that those mutations (A269D, L582V, and R825W) are not polymorphisms, as they were shown to be absent from a large number of euglycemic subjects. Login to comment
88 Moreover, one of these mutations, L582V, has been shown to cosegregate with diabetes in one previously published family (13). Login to comment

[hide] A rare mutation in ABCC8/SUR1 leading to altered A... Diabetes. 2008 Jun;57(6):1595-604. Epub 2008 Mar 17. Tarasov AI, Nicolson TJ, Riveline JP, Taneja TK, Baldwin SA, Baldwin JM, Charpentier G, Gautier JF, Froguel P, Vaxillaire M, Rutter GA
A rare mutation in ABCC8/SUR1 leading to altered ATP-sensitive K+ channel activity and beta-cell glucose sensing is associated with type 2 diabetes in adults.
Diabetes. 2008 Jun;57(6):1595-604. Epub 2008 Mar 17., [PMID:18346985]

Abstract [show]
OBJECTIVE: ATP-sensitive K(+) channels (K(ATP) channels) link glucose metabolism to the electrical activity of the pancreatic beta-cell to regulate insulin secretion. Mutations in either the Kir6.2 or sulfonylurea receptor (SUR) 1 subunit of the channel have previously been shown to cause neonatal diabetes. We describe here an activating mutation in the ABCC8 gene, encoding SUR1, that is associated with the development of type 2 diabetes only in adults. RESEARCH DESIGN AND METHODS: Recombinant K(ATP) channel subunits were expressed using pIRES2-based vectors in human embryonic kidney (HEK) 293 or INS1(832/13) cells and the subcellular distribution of c-myc-tagged SUR1 channels analyzed by confocal microscopy. K(ATP) channel activity was measured in inside-out patches and plasma membrane potential in perforated whole-cell patches. Cytoplasmic [Ca(2+)] was imaged using Fura-Red. RESULTS: A mutation in ABCC8/SUR1, leading to a Y356C substitution in the seventh membrane-spanning alpha-helix, was observed in a patient diagnosed with hyperglycemia at age 39 years and in two adult offspring with impaired insulin secretion. Single K(ATP) channels incorporating SUR1-Y356C displayed lower sensitivity to MgATP (IC(50) = 24 and 95 micromol/l for wild-type and mutant channels, respectively). Similar effects were observed in the absence of Mg(2+), suggesting an allosteric effect via associated Kir6.2 subunits. Overexpression of SUR1-Y356C in INS1(832/13) cells impaired glucose-induced cell depolarization and increased in intracellular free Ca(2+) concentration, albeit more weakly than neonatal diabetes-associated SUR1 mutants. CONCLUSIONS: An ABCC8/SUR1 mutation with relatively minor effects on K(ATP) channel activity and beta-cell glucose sensing causes diabetes in adulthood. These data suggest a close correlation between altered SUR1 properties and clinical phenotype.

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83 (E), wild type; (F), Y356C; (f), K1521N; (Ⅺ), H1023Y; (Œ), R248Q; (‚), L582V; (ૺ), R1379C. Login to comment
88 A: Currents from inside-out patches excised from HEK293 cells overexpressing recombinant Kir6.2/SUR1-wild type (WT), Kir6.2/SUR1-Y356C, and Kir6.2/SUR1-L582V in Mg2؉ -containing (left) and Mg2؉ -free (right) solution. Login to comment
94 D: MgATP concentration-inhibition curves for wild-type and Kir6.2/SUR1-L582V KATP channels. Login to comment
95 E: ATP (Mg2؉ -free) concentration-inhibition curves for wild-type and Kir6.2/SUR1-L582V KATP channels. Login to comment
120 To test whether the mutations associated with type 2 diabetes might affect stimulus-secretion coupling in beta-cells, we next measured the sensitivity to ATP of recombinant KATP channels carrying SUR-Y356C, -R248Q, and -K1521N and compared these to the ATP sensitivity of TND-associated mutants (4), L582V, H1023Y, and R1379C. Login to comment
132 Given the limited magnitude of the type 2 diabetes-associated mutant`s effects, we used a TND-associated SUR1 mutation, L582V (4), as a positive control. Login to comment
140 Heterozygous channels expressing SUR1-L582V (hetL582V) were also more ATP sensitive than homozygous SUR1-L582V channels (homL582V): IC50 ϭ 869 ␮mol/l and IC50 ϭ 1,140 ␮mol/l for het582V and hom582V, respectively (Fig. 2A and D) (Table 1). Login to comment
147 Thus, the gain-of-function effect of L582V mutation was mediated via Mg2ϩ -dependent activation, while the effect of Y356C apparently occurred through a different mechanism. Login to comment
152 Similarly, the cytoplasmic disposition of SUR1-L582V was not different from that of the wild-type SUR1 (Fig. 3E). Login to comment
153 Interestingly, we did note a tendency toward lower cell surface expression of SUR1-L582V (Fig. 3F) versus wild type. Login to comment
158 We therefore studied the effect on these two phenomena of the Y356C and L582V mutations in SUR1. Login to comment
177 TABLE 2 Parameters of ATP inhibition for KATP channels with mutant SUR1 subunit IC50 WT Y356C L582V ЉheteroЉ ЉhomoЉ ЉheteroЉ ЉhomoЉ 2 Mg2ϩ mmol/l 24 Ϯ 3 (5) 61 Ϯ 11 (10)* 95 Ϯ 9 (10)* 869 Ϯ 48 (6)* 1140 Ϯ 346 (6)* 0 Mg2ϩ mmol/l 8 Ϯ 1 (6) 25 Ϯ 5 (7)* 38 Ϯ 8 (8)* 17 Ϯ 3 (5)† 17 Ϯ 3 (6)† Data are means Ϯ SE (number of experiments). Login to comment
198 A, C, and E: Representative confocal images of cells expressing the SUR1 (wild-type [A], Y356C [C], and L582V [E]) subunit alone. Login to comment
200 B, D, and F: Representative images of cells expressing SUR1 (wild-type [B], Y356C [D], and L582V [F]) subunits together with Kir6.2. Login to comment
210 We observed that two mutations (Y356C and L582V) that are associated with phenotypes of different severity in heterozygous patients cause different shifts in the ATP sensitivity of the KATP channel (Fig. 2B and D). Login to comment
221 Thus, the Y356C mutant lead to a substantially less marked inhibition of glucose-induced [Ca2ϩ ]cyt increase than L582V (Fig. 5B). Login to comment
248 In contrast to Y356C, the activatory effect of mutations L582V (Fig. 3D) and H1023Y (4) was not observed under Mg2ϩ -free conditions, suggesting that these mutations exert their effects via the SUR1 NBDs. Login to comment