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Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY
DIAB-6127; No. of Pages 5 diabetes research and clinical practice xxx (2014) xxx.e1–xxx.e5
Contents available at ScienceDirect
Diabetes Research and Clinical Practice journ al h ome pa ge : www .elsevier.co m/lo cate/diabres
Brief report
Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY Letı´cia S. Weinert a, Sandra P. Silveiro a, Fernando M.A. Giuffrida b,c, Vivian T. Cunha a, Caroline Bulca˜o b, Luis Eduardo Calliari d, Thais Della Manna e, Ilda S. Kunii f, Renata P. Dotto f, Magnus R. Dias-da-Silva f, Andre´ F. Reis f,g,* a
Endocrinology Unit-Hospital de Clı´nicas de Porto Alegre, Postgraduate Fellowship Program in EndocrinologyUniversidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil b Centro de Endocrinologia do Estado da Bahia (CEDEBA), Salvador, Brazil c Universidade do Estado da Bahia (UNEB), Salvador, Brazil d Pediatric Endocrinology Unit, Santa Casa de Miserico´rdia, Sa˜o Paulo, Brazil e Instituto da Crianc¸a, Hospital das Clı´nicas, Universidade de Sa˜o Paulo (USP), Brazil f Laboratory of Molecular and Translacional Endocrinology, Universidade Federal de Sa˜o Paulo (UNIFESP), Brazil g Diabetes Center, Universidade Federal de Sa˜o Paulo (UNIFESP), Brazil
article info
abstract
Article history:
Thirty-two Brazilian families with MODY phenotype were screened for GCK and HNF1A
Received 1 August 2014
mutations. GCK mutations were found in 8 families, all patients with mild asymptomatic
Accepted 4 August 2014
hyperglycaemia; 3 of them are novel: p.Asp365Asn, p.Gly81Asp and p.Val253Leu. Previously
Available online xxx
described mutations in HNF1A were found in 2 families. # 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Maturity-onset diabetes of the young (MODY) Monogenic diabetes Glucokinase HNF1A
1.
Introduction
Maturity-onset diabetes of the young (MODY) is a heterogeneous group of rare subtypes of diabetes mellitus (DM), caused
by mutations in at least 13 different genes and frequently misdiagnosed as type 1 or type 2 DM [1,2]. MODY frequency is around 1–2% among patients with DM [3]. Glucokinase (GCK) and hepatocyte nuclear factor homeobox-1A (HNF1A) are the most commonly [1,2,4] affected genes.
* Corresponding author at: Universidade Federal de Sa˜o Paulo (UNIFESP), Diabetes Center, R. Estado de Israel, 639-Vila Mariana, Sa˜o Paulo, Sa˜o Paulo, SP 04022-001, Brazil. Tel.:+55 11 55764856; fax: +55 11 55231669. E-mail address: [email protected] (A.F. Reis). http://dx.doi.org/10.1016/j.diabres.2014.08.006 0168-8227/# 2014 Elsevier Ireland Ltd. All rights reserved.
Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
Family/ patient
Gender
Age (years)
Age at diagnosis (years)
BMI (kg/m2)
Fasting glucose (mg/dL)
HbA1c, % (mmol/ mol)
Chronic complications
C-peptide (ng/mL)
C-reactive protein (mg/L)
Drugs
Gene/ nucleotide change
Aminoacid substitution
Previous description
A M
54
23
24.7
128
7.2 (55)
Diabetic nephropathy and retinopathy
1.6
NA
Metformin and glyburide
HNF1A/c.24_ 35dup12
p.Gln9_Leu12du
[7]
Proband
F
42
27
19.2
194
6.7 (50)
No
1.6
<0.12
Metformin, glyburide and NPH insulin
HNF1A/c.872dupC
p.Gly292fs
[12]
Father Proband
M M
50 19
45 17
28.8 24.9
132 NA
6.5 (48) NA
No No
NA NA
NA NA
Glyburide No
GCK/c.242G>A GCK/c.242G>A
p.Gly81Asp p.Gly81Asp
New mutation New mutation
Proband
M
15
13
20.6
101
6.4 (46)
No
1.6
NA
No
GCK/c.1093G>A
p.Asp365Asn
New mutation
Proband
F
26
19
19.8
110
6.3 (45)
No
2.0
1.2
Metformin
GCK/c.781G>A
p.Gly261Arg
([4], [12–14])
Son Proband
M F
9 41
7 NA
16.5 22.7
108 100
5.8 (40) NA
No NA
NA NA
NA NA
No No
GCK/c.1136C>T GCK/c.1136C>T GCK/c.1136C>T
p.Ala379Val p.Ala379Val
[4]a [4]a
Son
M
10
9
15.7
114
6.0 (42)
No
1.0
NA
No
GCK/c.47T>A
[4]
Proband
F
43
32
22.1
105
5.6 (38)
No
1.3
0.08
No
GCK/c.47T>A
p.Val16Glu (exon 2) p.Val16Glu (exon 2)
Son
M
5
1
15.1
111
6.6 (49)
No
0.4
NA
No
GCK/c.757G>C
Proband
F
33
NA
24.2
110
6.1 (43)
No
1.0
0.39
No
GCK/c.757G>C
Son
M
1
4 months
16.0
108
6.0 (40)
No
NA
NA
No
GCK/c.757G>C
Son
M
10
9
15.6
119
5.9 (41)
No
1.6
NA
No
GCK/c.626C>T
Proband
F
39
22
21.0
120
6.2 (44)
No
3.4
NA
DPP IV inhibitor
GCK/c.626C>T
Proband
F
15
11
16.0
127
6.6 (49)
No
2.4
NA
No
GCK/c.423delCA
B
C
D E F
G
[4]
H p.Val253Leu (exon 7) p.Val253Leu (exon7) p.Val253Leu (exon 7)
New mutation New mutation New mutation
I pThr209Met (exon 6) pThr209Met (exon 6)
([4], [16])
p.Hist141fsX20 (exon 4)
[4]
[4,16]b
J
BMI: Body mass index, M: male; F: female; NA: not available; DPP IV: dipeptidyl peptidase IV. With functional study. b Diagnosis during pregnancy. a
diabetes research and clinical practice xxx (2014) xxx.e1–xxx.e5
Proband
DIAB-6127; No. of Pages 5
e2
Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
Table 1 – Clinical and genetic characteristics of participants.
DIAB-6127; No. of Pages 5 diabetes research and clinical practice xxx (2014) xxx.e1–xxx.e5
MODY is an autosomal dominant form of diabetes more frequently diagnosed before 25 years of age and caused by a variable primary insulin secretion defect. GCK-MODY is characterised by mild non-progressive familial hyperglycaemia [5]. HNF1A-MODY, as well as MODY caused by other transcription factors, should be suspected in families with two or more generations of diabetic members and autosomal dominant inheritance [1]. Despite its low prevalence, MODY is not a single entity but has genetic, metabolic, and clinical heterogeneity. Therefore, efforts in characterising different MODY populations may shed light on the understanding of pathophysiology and genetic susceptibility of altered insulin secretion and response to therapy upon different ethnic backgrounds. Herein, we aimed to report major clinical and genetic features of a Brazilian cohort referred to MODY molecular diagnosis, including three unreported GCK missense mutations. We focused on HNF1A and GCK mutation screening and the description of novel GCK-MODY mutations.
2.
Materials and methods
Thirty-two Brazilian families with phenotypes suggestive of MODY were referred to genetic evaluation in the Laboratory of Molecular and Translational Endocrinology – Universidade Federal de Sa˜o Paulo (UNIFESP) utilising previously described methods [5], as part of a collaborative task force for MODY molecular diagnosis. Clinical and laboratory data were obtained from medical assistants from routine care. This study was approved by the Ethics Committee of UNIFESP and of the Hospital de Clı´nicas de Porto Alegre. All patients
e3
or legal guardians agreed to have the molecular test performed and signed the informed consent.
3.
Results
We identified GCK gene mutations in 8 families (Table 1). Three missense mutations had not been previously reported (p.Asp365Asn, p.Gly81Asp and p.Val253Leu). Cosegregation with hyperglycaemia was found in available family members for mutations p.Gly81Asp and p.Val253Leu (Fig. 1). In the other case with the p.Asp365Asn mutation, no other family members were available. Individuals with GCK-MODY had mild asymptomatic hyperglycaemia (fasting glucose 113 10 mg/dL and HbA1c 6.1 0.3%/43.2 3.3 mmol/mol), no use of antidiabetic drugs except three patients, absence of chronic diabetic complications, normal lipid profile, and normal blood pressure. Median age at diagnosis of hyperglycaemia was 12 years and one participant, the brother of the proband, was only 4 months old when diagnosed in the family with the p.Val253Leu mutation. This child had mild asymptomatic hyperglycaemia, was in good health and growing properly. During his last medical visit, at the age of 1 year and 2 months, he was 10.5 kg (percentile 25–50) and 81 cm (percentile 50–75). Previously described mutations in HNF1A gene were also found in 2 participants (Table 1). Patient carrying mutation p.Gly292fs required insulin therapy 10 years after the diagnosis of diabetes (10 units of NPH insulin). The other one, with mutation p.Gln9_Leu12dup, had good glucose control with oral antidiabetic drugs but was diagnosed with diabetic retinopathy and nephropathy. Both patients had detectable levels of fasting C-peptide (1.6 ng/ml).
A
45 y Wt /M
17 y Wt/M
B
15 y
6y
6y
?
Wt/M
1y Wt /M
4m Wt /M
Fig. 1 – Heredogram of family C, affected by the novel mutation p.Gly81Asp (A) and of family H, affected by the novel mutation p.Val253Leu (B). Number describes age at diagnosis of hyperglycaemia. Arrow identifies the probands. Question mark denotes unknown glycaemic status. Wt/M denotes tested patients with mutations. Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
DIAB-6127; No. of Pages 5
e4
4.
diabetes research and clinical practice xxx (2014) xxx.e1–xxx.e5
Discussion
In this manuscript we reported 10 Brazilian families with genetic diagnosis of MODY and classic clinical profile. Mutations of GCK and HNF1A gene are the most frequently found in various studied population [2,4]. In Brazil, previous studies have also described GCK-MODY and HNF1A-MODY patients [5–9]. In 2 of the 3 novel mutations in GCK gene (p.Gly81Asp and p.Val253Leu), cosegregation with hyperglycaemia was found in available family members, which strongly indicates that these mutations are causative of hyperglycaemia. In the other 5 families, GCK mutations have been previously described in other populations, among them: p.Ala379Val and pThr209Met, with functional studies demonstrating reduced enzymatic activity [10,11], and p.Val16Glu, p.Hist141fsX20, and p.Gly261Arg were described in many populations including Spanish patients [4,12–15]. Among mutations found in the HNF1A gene, p.Gly292fs is the most frequent worldwide [16] and had been previously described in Brazilian patients [9]. The other HNF1A mutation had also been reported in Brazilian individuals [7]. All evaluated participants had clinical criteria suggestive of MODY, in agreement with best practice recommendations for genetic testing [2]. One patient was first diagnosed with hyperglycaemia during pregnancy, a common finding in MODY patients. The two patients with HNF1A-MODY also had classic features of this subtype such as young age at diagnosis, family history of diabetes, normal body mass index, no evidence of insulin resistance, and sensitivity to sulfonylurea treatment. Genetic testing for GCK and HNF1A mutations is considered essential, since it confirms diagnosis of MODY and correctly classifies its subtype [2]. Testing also enables the attending physician to provide the appropriate treatment for each patient, since GCK-MODY patients usually do not require pharmacological treatment [4] and HNF1A-MODY patients usually respond to sulfonylureas [2]. Moreover, since children are at 50% risk of inheriting the mutations, an appropriate counselling can be provided and genetic testing can be offered to family members. HNF1A and GCK mutations are frequent in Brazil and an important cause of monogenic diabetes, although no data about prevalence can be derived from our sample. Therefore, correct clinical suspicion and molecular investigation are of utmost importance to correctly diagnose and treat these individuals in our population. However, a large proportion of Brazilians with a clinical phenotype of transcription factor MODY remain undiagnosed and should be investigated for other rarer forms in future studies.
Conflict of interest statement There is no authors’ conflict of interest.
Acknowledgments Funding: Sa˜o Paulo State Research Foundation-FAPESP grants 2011/20747-8 (to M.R.D.S.). Postgraduate Fellowship Programme in Endocrinology-Universidade Federal do Rio Grande do Sul
(UFRGS). Renata P. Dotto (PhD) is student from the Brazilian Research Council (CNPq).
references
[1] Fajans SS, Bell GI. MODY: history, genetics, pathophysiology, and clinical decision making. Diabetes Care 2011;34(8): 1878–84. http://dx.doi.org/10.2337/dc11-dc0035. [2] Ellard S, Bellanne´-Chantelot C, Hattersley AT, European Molecular Genetics Quality Network EMQN MODY group. Best practice guidelines for the molecular genetic diagnosis of maturity-onset diabetes of the young. Diabetologia 2008;51(4):546–53. http://dx.doi.org/10.1007/s00125-008-0942-y. [3] Ledermann HM. Is maturity onset diabetes at young age (MODY) more common in Europe than previously assumed? Lancet 1995;345(8950):648. [4] Estalella I, Rica I, Perez de Nanclares G, Bilbao JR, Vazquez JA, San Pedro JI, et al. Mutations in GCK and HNF-1alpha explain the majority of cases with clinical diagnosis of MODY in Spain. Clin Endocrinol 2007;67(4):538–46. http:// dx.doi.org/10.1111/j.1365-2265.2007.02921.x. [5] Furuzawa GK, Giuffrida FMA, Oliveira CSV, Chacra AR, Dib SA, Reis AF. Low prevalence of MODY2 and MODY3 mutations in Brazilian individuals with clinical MODY phenotype. Diabetes Res Clin Pract 2008;81(3):e12–4. http:// dx.doi.org/10.1016/j.diabres.2008.06.011. [6] Giuffrida FMA, Calliari LE, Manna TD, Ferreira JG, SaddiRosa P, Kunii IS, et al. A novel glucokinase deletion (p.Lys32del) and five previously described mutations cosegregate with the phenotype of mild familial hyperglycaemia (MODY2) in Brazilian families. Diabetes Res Clin Pract 2013;100(2):e42–5. http://dx.doi.org/10.1016/j. diabres.2013.01.029. [7] Maraschin JdeF, Kannengiesser C, Murussi N, Campagnolo N, Canani LH, Gross JL, et al. HNF1alpha mutations are present in half of clinically defined MODY patients in South-Brazilian individuals. Arq Brasil Endocrinol Metab 2008;52(8):1326–31. [8] DellaManna T, da Silva MR, Chacra AR, Kunii IS, Rolim AL, Furuzawa GK, et al. Clinical follow-up of two Brazilian subjects with glucokinase-MODY (MODY2) with description of a novel mutation. Arq Brasil Endocrinol Metab 2012;56(8):490–5. [9] Moises RS, Reis AF, Morel V, Chacra AR, Dib SA, BellanneChantelot C, et al. Prevalence of maturity-onset diabetes of the young mutations in Brazilian families with autosomaldominant early-onset type 2 diabetes. Diabetes Care 2001;24(4):786–8. [10] Estalella I, Garcia-Gimeno MA, Marina A, Castan˜o L, Sanz P. Biochemical characterization of novel glucokinase mutations isolated from Spanish maturity-onset diabetes of the young (MODY2) patients. J Hum Genet 2008;53(5): 460–6. http://dx.doi.org/10.1007/s10038-008-0271-275. [11] Miller SP, Anand GR, Karschnia EJ, Bell GI, LaPorte DC, Lange AJ. Characterization of glucokinase mutations associated with maturity-onset diabetes of the young type 2 (MODY-2): different glucokinase defects lead to a common phenotype. Diabetes 1999;48(8):1645–51. [12] Massa O, Meschi F, Cuesta-Munoz A, Caumo A, Cerutti F, Toni S, et al. High prevalence of glucokinase mutations in Italian children with MODY. Influence on glucose tolerance, first-phase insulin response, insulin sensitivity and BMI. Diabetologia 2001;44(7):898–905. [13] Thomson KL, Gloyn AL, Colclough K, Batten M, Allen LIS, Beards F, et al. Identification of 21 novel glucokinase (GCK) mutations in UK and European Caucasians with maturityonset diabetes of the young (MODY). Hum Mutat 2003;22(5):417. http://dx.doi.org/10.1002/humu.9186.
Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
DIAB-6127; No. of Pages 5 diabetes research and clinical practice xxx (2014) xxx.e1–xxx.e5
[14] Velho G, Blanche´ H, Vaxillaire M, Bellanne´-Chantelot C, Pardini VC, Timsit J, et al. Identification of 14 new glucokinase mutations and description of the clinical profile of 42 MODY-2 families. Diabetologia 1997;40(2):217–24. http://dx.doi.org/10.1007/s001250050666. [15] Codner E, Rocha A, Deng L, Martı´nez-Aguayo A, Godoy C, Mericq V, et al. Mild fasting hyperglycemia in children: high rate of glucokinase mutations and some risk of developing type 1 diabetes mellitus. Pediatr Diabetes
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2009;10(6):382–8. http://dx.doi.org/10.1111/j.13995448.2009.00499.x. [16] Colclough K, Bellanne´-Chantelot C, Saint-Martin C, Flanagan SE, Ellard S. Mutations in the genes encoding the transcription factors hepatocyte nuclear factor 1 alpha and 4 alpha in maturity-onset diabetes of the young and hyperinsulinemic hypoglycemia. Hum Mutat 2013;34(5):669–85. http://dx.doi.org/10.1002/humu.22279.
Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
Contents available at ScienceDirect
Diabetes Research and Clinical Practice journ al h ome pa ge : www .elsevier.co m/lo cate/diabres
Brief report
Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY Letı´cia S. Weinert a, Sandra P. Silveiro a, Fernando M.A. Giuffrida b,c, Vivian T. Cunha a, Caroline Bulca˜o b, Luis Eduardo Calliari d, Thais Della Manna e, Ilda S. Kunii f, Renata P. Dotto f, Magnus R. Dias-da-Silva f, Andre´ F. Reis f,g,* a
Endocrinology Unit-Hospital de Clı´nicas de Porto Alegre, Postgraduate Fellowship Program in EndocrinologyUniversidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil b Centro de Endocrinologia do Estado da Bahia (CEDEBA), Salvador, Brazil c Universidade do Estado da Bahia (UNEB), Salvador, Brazil d Pediatric Endocrinology Unit, Santa Casa de Miserico´rdia, Sa˜o Paulo, Brazil e Instituto da Crianc¸a, Hospital das Clı´nicas, Universidade de Sa˜o Paulo (USP), Brazil f Laboratory of Molecular and Translacional Endocrinology, Universidade Federal de Sa˜o Paulo (UNIFESP), Brazil g Diabetes Center, Universidade Federal de Sa˜o Paulo (UNIFESP), Brazil
article info
abstract
Article history:
Thirty-two Brazilian families with MODY phenotype were screened for GCK and HNF1A
Received 1 August 2014
mutations. GCK mutations were found in 8 families, all patients with mild asymptomatic
Accepted 4 August 2014
hyperglycaemia; 3 of them are novel: p.Asp365Asn, p.Gly81Asp and p.Val253Leu. Previously
Available online xxx
described mutations in HNF1A were found in 2 families. # 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Maturity-onset diabetes of the young (MODY) Monogenic diabetes Glucokinase HNF1A
1.
Introduction
Maturity-onset diabetes of the young (MODY) is a heterogeneous group of rare subtypes of diabetes mellitus (DM), caused
by mutations in at least 13 different genes and frequently misdiagnosed as type 1 or type 2 DM [1,2]. MODY frequency is around 1–2% among patients with DM [3]. Glucokinase (GCK) and hepatocyte nuclear factor homeobox-1A (HNF1A) are the most commonly [1,2,4] affected genes.
* Corresponding author at: Universidade Federal de Sa˜o Paulo (UNIFESP), Diabetes Center, R. Estado de Israel, 639-Vila Mariana, Sa˜o Paulo, Sa˜o Paulo, SP 04022-001, Brazil. Tel.:+55 11 55764856; fax: +55 11 55231669. E-mail address: [email protected] (A.F. Reis). http://dx.doi.org/10.1016/j.diabres.2014.08.006 0168-8227/# 2014 Elsevier Ireland Ltd. All rights reserved.
Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
Family/ patient
Gender
Age (years)
Age at diagnosis (years)
BMI (kg/m2)
Fasting glucose (mg/dL)
HbA1c, % (mmol/ mol)
Chronic complications
C-peptide (ng/mL)
C-reactive protein (mg/L)
Drugs
Gene/ nucleotide change
Aminoacid substitution
Previous description
A M
54
23
24.7
128
7.2 (55)
Diabetic nephropathy and retinopathy
1.6
NA
Metformin and glyburide
HNF1A/c.24_ 35dup12
p.Gln9_Leu12du
[7]
Proband
F
42
27
19.2
194
6.7 (50)
No
1.6
<0.12
Metformin, glyburide and NPH insulin
HNF1A/c.872dupC
p.Gly292fs
[12]
Father Proband
M M
50 19
45 17
28.8 24.9
132 NA
6.5 (48) NA
No No
NA NA
NA NA
Glyburide No
GCK/c.242G>A GCK/c.242G>A
p.Gly81Asp p.Gly81Asp
New mutation New mutation
Proband
M
15
13
20.6
101
6.4 (46)
No
1.6
NA
No
GCK/c.1093G>A
p.Asp365Asn
New mutation
Proband
F
26
19
19.8
110
6.3 (45)
No
2.0
1.2
Metformin
GCK/c.781G>A
p.Gly261Arg
([4], [12–14])
Son Proband
M F
9 41
7 NA
16.5 22.7
108 100
5.8 (40) NA
No NA
NA NA
NA NA
No No
GCK/c.1136C>T GCK/c.1136C>T GCK/c.1136C>T
p.Ala379Val p.Ala379Val
[4]a [4]a
Son
M
10
9
15.7
114
6.0 (42)
No
1.0
NA
No
GCK/c.47T>A
[4]
Proband
F
43
32
22.1
105
5.6 (38)
No
1.3
0.08
No
GCK/c.47T>A
p.Val16Glu (exon 2) p.Val16Glu (exon 2)
Son
M
5
1
15.1
111
6.6 (49)
No
0.4
NA
No
GCK/c.757G>C
Proband
F
33
NA
24.2
110
6.1 (43)
No
1.0
0.39
No
GCK/c.757G>C
Son
M
1
4 months
16.0
108
6.0 (40)
No
NA
NA
No
GCK/c.757G>C
Son
M
10
9
15.6
119
5.9 (41)
No
1.6
NA
No
GCK/c.626C>T
Proband
F
39
22
21.0
120
6.2 (44)
No
3.4
NA
DPP IV inhibitor
GCK/c.626C>T
Proband
F
15
11
16.0
127
6.6 (49)
No
2.4
NA
No
GCK/c.423delCA
B
C
D E F
G
[4]
H p.Val253Leu (exon 7) p.Val253Leu (exon7) p.Val253Leu (exon 7)
New mutation New mutation New mutation
I pThr209Met (exon 6) pThr209Met (exon 6)
([4], [16])
p.Hist141fsX20 (exon 4)
[4]
[4,16]b
J
BMI: Body mass index, M: male; F: female; NA: not available; DPP IV: dipeptidyl peptidase IV. With functional study. b Diagnosis during pregnancy. a
diabetes research and clinical practice xxx (2014) xxx.e1–xxx.e5
Proband
DIAB-6127; No. of Pages 5
e2
Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
Table 1 – Clinical and genetic characteristics of participants.
DIAB-6127; No. of Pages 5 diabetes research and clinical practice xxx (2014) xxx.e1–xxx.e5
MODY is an autosomal dominant form of diabetes more frequently diagnosed before 25 years of age and caused by a variable primary insulin secretion defect. GCK-MODY is characterised by mild non-progressive familial hyperglycaemia [5]. HNF1A-MODY, as well as MODY caused by other transcription factors, should be suspected in families with two or more generations of diabetic members and autosomal dominant inheritance [1]. Despite its low prevalence, MODY is not a single entity but has genetic, metabolic, and clinical heterogeneity. Therefore, efforts in characterising different MODY populations may shed light on the understanding of pathophysiology and genetic susceptibility of altered insulin secretion and response to therapy upon different ethnic backgrounds. Herein, we aimed to report major clinical and genetic features of a Brazilian cohort referred to MODY molecular diagnosis, including three unreported GCK missense mutations. We focused on HNF1A and GCK mutation screening and the description of novel GCK-MODY mutations.
2.
Materials and methods
Thirty-two Brazilian families with phenotypes suggestive of MODY were referred to genetic evaluation in the Laboratory of Molecular and Translational Endocrinology – Universidade Federal de Sa˜o Paulo (UNIFESP) utilising previously described methods [5], as part of a collaborative task force for MODY molecular diagnosis. Clinical and laboratory data were obtained from medical assistants from routine care. This study was approved by the Ethics Committee of UNIFESP and of the Hospital de Clı´nicas de Porto Alegre. All patients
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or legal guardians agreed to have the molecular test performed and signed the informed consent.
3.
Results
We identified GCK gene mutations in 8 families (Table 1). Three missense mutations had not been previously reported (p.Asp365Asn, p.Gly81Asp and p.Val253Leu). Cosegregation with hyperglycaemia was found in available family members for mutations p.Gly81Asp and p.Val253Leu (Fig. 1). In the other case with the p.Asp365Asn mutation, no other family members were available. Individuals with GCK-MODY had mild asymptomatic hyperglycaemia (fasting glucose 113 10 mg/dL and HbA1c 6.1 0.3%/43.2 3.3 mmol/mol), no use of antidiabetic drugs except three patients, absence of chronic diabetic complications, normal lipid profile, and normal blood pressure. Median age at diagnosis of hyperglycaemia was 12 years and one participant, the brother of the proband, was only 4 months old when diagnosed in the family with the p.Val253Leu mutation. This child had mild asymptomatic hyperglycaemia, was in good health and growing properly. During his last medical visit, at the age of 1 year and 2 months, he was 10.5 kg (percentile 25–50) and 81 cm (percentile 50–75). Previously described mutations in HNF1A gene were also found in 2 participants (Table 1). Patient carrying mutation p.Gly292fs required insulin therapy 10 years after the diagnosis of diabetes (10 units of NPH insulin). The other one, with mutation p.Gln9_Leu12dup, had good glucose control with oral antidiabetic drugs but was diagnosed with diabetic retinopathy and nephropathy. Both patients had detectable levels of fasting C-peptide (1.6 ng/ml).
A
45 y Wt /M
17 y Wt/M
B
15 y
6y
6y
?
Wt/M
1y Wt /M
4m Wt /M
Fig. 1 – Heredogram of family C, affected by the novel mutation p.Gly81Asp (A) and of family H, affected by the novel mutation p.Val253Leu (B). Number describes age at diagnosis of hyperglycaemia. Arrow identifies the probands. Question mark denotes unknown glycaemic status. Wt/M denotes tested patients with mutations. Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006
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Discussion
In this manuscript we reported 10 Brazilian families with genetic diagnosis of MODY and classic clinical profile. Mutations of GCK and HNF1A gene are the most frequently found in various studied population [2,4]. In Brazil, previous studies have also described GCK-MODY and HNF1A-MODY patients [5–9]. In 2 of the 3 novel mutations in GCK gene (p.Gly81Asp and p.Val253Leu), cosegregation with hyperglycaemia was found in available family members, which strongly indicates that these mutations are causative of hyperglycaemia. In the other 5 families, GCK mutations have been previously described in other populations, among them: p.Ala379Val and pThr209Met, with functional studies demonstrating reduced enzymatic activity [10,11], and p.Val16Glu, p.Hist141fsX20, and p.Gly261Arg were described in many populations including Spanish patients [4,12–15]. Among mutations found in the HNF1A gene, p.Gly292fs is the most frequent worldwide [16] and had been previously described in Brazilian patients [9]. The other HNF1A mutation had also been reported in Brazilian individuals [7]. All evaluated participants had clinical criteria suggestive of MODY, in agreement with best practice recommendations for genetic testing [2]. One patient was first diagnosed with hyperglycaemia during pregnancy, a common finding in MODY patients. The two patients with HNF1A-MODY also had classic features of this subtype such as young age at diagnosis, family history of diabetes, normal body mass index, no evidence of insulin resistance, and sensitivity to sulfonylurea treatment. Genetic testing for GCK and HNF1A mutations is considered essential, since it confirms diagnosis of MODY and correctly classifies its subtype [2]. Testing also enables the attending physician to provide the appropriate treatment for each patient, since GCK-MODY patients usually do not require pharmacological treatment [4] and HNF1A-MODY patients usually respond to sulfonylureas [2]. Moreover, since children are at 50% risk of inheriting the mutations, an appropriate counselling can be provided and genetic testing can be offered to family members. HNF1A and GCK mutations are frequent in Brazil and an important cause of monogenic diabetes, although no data about prevalence can be derived from our sample. Therefore, correct clinical suspicion and molecular investigation are of utmost importance to correctly diagnose and treat these individuals in our population. However, a large proportion of Brazilians with a clinical phenotype of transcription factor MODY remain undiagnosed and should be investigated for other rarer forms in future studies.
Conflict of interest statement There is no authors’ conflict of interest.
Acknowledgments Funding: Sa˜o Paulo State Research Foundation-FAPESP grants 2011/20747-8 (to M.R.D.S.). Postgraduate Fellowship Programme in Endocrinology-Universidade Federal do Rio Grande do Sul
(UFRGS). Renata P. Dotto (PhD) is student from the Brazilian Research Council (CNPq).
references
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Please cite this article in press as: Weinert LSDTDDIFFD, et al. Three unreported glucokinase (GCK) missense mutations detected in the screening of thirty-two Brazilian kindreds for GCK and HNF1A-MODY. Diabetes Res Clin Pract (2014), http://dx.doi.org/10.1016/j.diabres.2014.08.006