Anticorpi Anti Gliadina Deamidata:un nuovo utile marker per la malattia celiaca

Sergio AmarriUO Pediatria

Azienda Ospedaliera Reggio Emilia

Sintomi tipici di malattia celiaca• diarrea• vomito• distensione addominale• perdita di peso• pallore• anoressia• magrezza• edemi• irritabilità

Manifestazioni extraintestinali• Dermatite erpetiforme• Anemia sideropenica di ndd• Bassa statura• Ritardo puberale• Infertilità ed aborti ricorrenti• Alopecia areata• Stomatite aftosa• Ipoplasia smalto dentario• Ipertransaminasemia di ndd• Epilessia farmaco-resistente, atassia , polineurite• Osteoporosi• Miocardiopatia dilatativa• Artriti

Quadri clinici e malattie associate

• Tiroidite di Hashimoto• Diabete tipo I: 3 – 8 %• Sindrome Down: 5 – 12 %• Sindrome di Turner• Sindrome di Sjogren• Deficit IgA• Sclerosi multipla• Cirrosi biliare primitiva

FORMA CLASSICA DI MALATTIA CELIACA

CELIACHIA

Biopsia positiva

IgA sieriche + anti-tTG positiviAGA < 2 anni di vita

Sintomi di malassorbimento

Sensibilità e Specificità (Istologia)Gold Standard

Test (sierologia)

positivo negativo

positivo a b

negativo c d

Sensibilità = a/(a+c) Specificità = d/(b+d) Alta sensibilità = pochi falsi negativi (c)!

Alta specificità = pochi falsi positivi (b)!

Combinazioni marker celiachiaEMA-IgA AGA-IgA* AGA-IgG* Diagnosi

anti-tTG IgA anti-tTG IgG

+ + + quasi certa

+ - + probabile

+ + - Più probabile

+ - - Probabile

- + + Probabile

- + - meno probabile

- - + Improbabile (deficit IgA!)

* AGA < 2 anni di età. Anti-tTG positivi conferma EMA

Utilità marker celiachia • Anti-transglutaminasi IgA (il più utile)

– Limiti: deficit di IgA e primi due anni di vita

• EMA IgA (meno sensibile e più specifico della tTG si usa per conferma)– Limiti: costoso e legato all’interpretazione

dell’operatore

• Anti-transglutaminasi IgG (poco accurato)

• AGA IgA (utile sotto i due anni di vita)

• AGA IgG (di scarsa utilità)

DGP

Celiac Disease NEJM 2007; 357:1731-1743

Peter H.R. Green and Christophe Cellier

Lewis&Scott. Deamidated gliadin and tTG compared as screening for coeliac disease. Aliment Pharmacol 2010

IgA - DGP

IgA - tTG

Lewis&Scott. Deamidated gliadin and tTG compared as screening for coeliac disease. Aliment Pharmacol 2010

IgA - DGP IgA - tTG

Combination testing for antibodies in the diagnosis of coeliac disease: comparison of multiplex immunoassay ELISA methods. Aliment Pharmacol 2008; 28: 805-13

Testκ-Statistics

Sensitivity (%) Specificity (%) Accuracy (%)

MIA ELISA† MIA ELISA† MIA ELISA†

DGP IgA 0.89 71.6* 75.0* 92.7 95.2 83.9* 86.8*

DGP IgG 0.86 66.3 65.2 96.8 98.4 83.8 84.3

TTG IgA 0.97 81.8* 79.3* 98.4 98.4 91.5* 90.5*

TTG IgG 0.48 13.0 28.3 100.0 96.8 63.0 67.6

Combination testing for antibodies in the diagnosis of coeliac disease: comparison of multiplex immunoassay ELISA methods. Aliment Pharmacol 2008; 28: 805-13

Test κ-Statistics

Sensitivity (%) Specificity (%) Accuracy (%)

MIA ELISA MIA ELISA MIA ELISA

DGP IgA or IgG

0.87 77.8

78.3 90.2

94.4 85.0

87.5

TTG IgA or IgG

0.93 82.2

80.4 98.4

96.0 91.5

89.4

DGP IgA or TTG IgA

0.93 83.0

83.0 92.7

95.2 86.6

90.1

DGP IgG or TTG IgA

0.96 84.4

82.6 95.9

97.6 91.1

91.2

DGP IgA or IgG or TTG IgA

0.91 85.6

83.7 90.2

94.4 88.3

89.8

DGP IgA or IgG or TTG IgA or IgG

0.88 85.6

83.7 90.2

91.9 88.3

88.4

Combination testing for antibodies in the diagnosis of coeliac disease: comparison of multiplex immunoassay ELISA methods. Aliment Pharmacol 2008; 28: 805-13

Test

Sensitivity (%) Specificity (%) Accuracy (%)

MIA ELISA MIA ELISA MIA ELISA

DGP IgA and IgG

0.90 60.0 61.4 99.2 99.2 82.7 83.5

TTG IgA and IgG

0.50 11.1 25.3 100.0 99.2 62.6 68.7

DGP IgA and TTG IgA

0.96 70.5 71.3 98.4 98.4 86.7 87.2

DGP IgG and TTG IgA

0.88 63.3 60.9 99.2 99.2 84.1 83.4

DGP IgA and IgG and TTG IgA

0.91 60.0 58.6 99.2 99.2 82.7 82.5

DGP IgA and IgG and TTG IgA and IgG

0.57 11.1 20.7 100.0 99.2 62.6 66.8

Volta et al. Deamidated gliadin peptide antibodies as a routine test for celiac disease: a prospective analysis

J Clin Gastroenterol 2009

Volta et al. Deamidated gliadin peptide antibodies as a routine test for celiac disease: a prospective analysis

J Clin Gastroenterol 2009

test SENSIBILITA’ SPECIFICITA’

IgA tTG 93,7% 96,6%

IgA EMA 91,6% 100%

IgA DGP 84,3% 79,8%

IgG DGP 82,3% 98,9%

Copyright ©2009 American Association for Clinical Chemistry

Basso, D. et al. Clin Chem 2009;55:150-157

Individual values of AGA IgA II, AGA IgG II, and tTG IgA measured in the sera of children with (CD) or without (CS) typical celiac disease duodenal histology

Basso, D. et al. Clin Chem 2009;55:150-157

Positive result Sensitivity Specificity PPV NPV

AGA IgA II and tTG IgA 80.7 100 100 80.4

AGA IgA II or tTG IgA 92.5 90.6 92.5 90.6

AGA IgG II and tTG IgA

77.6 99.2 99.2 77.8

AGA IgG II or tTG IgA

95.0 95.3 96.2 93.8

AGA IgA II and AGA IgG II and tTG IgA

72.0 100 100 73.8

AGA IgA II or AGA IgG II or tTG IgA

95.0 89.8 92.2 93.4

Copyright ©2009 American Association for Clinical Chemistry

Basso, D. et al. Clin Chem 2009;55:150-157

ROC curves of AGA IgA II, AGA IgG II, and tTG IgA in distinguishing celiac disease from control children without total IgA deficiency

Copyright ©2009 American Association for Clinical Chemistry

Basso, D. et al. Clin Chem 2009;55:150-157

Median values, interquartile range, and outliers of AGA IgA II, AGA IgG II, and tTG IgA of children with CD subdivided according to Marsh-Oberhuber classification

Sensitivity (%) of antibody tests at more than 99% specificity*

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Antibodies Against Deamidated Gliadin as New and Accurate Biomarkers of Childhood Coeliac DiseaseJPGN 2009: 49;52-58

•

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Antibodies Against Deamidated Gliadin as New and Accurate Biomarkers of Childhood Coeliac DiseaseJPGN 2009: 49;52-58

25

Serum and intestinal celiac disease-associated antibodies in children with celiac disease < 2 years of age JPGN 2010; 50:43-48

(Amarri & Volta)Pazienti celiaci sesso: 4 F, 3M

età: range 16 – 28 mesi

sintomi all’esordio: diarrea, addome globoso, ipotonia muscolare, calo ponderale, astenia, famigliarità (1)

vn DGP-AGA IgG <10 AU

EmA IgA <1:5

tTG IgA <16 AU

AGA IgA*

AGA IgG <10

Biopsia

DRG 19.3 1:160 118.0 3A-B IS 126.0 1:640 129.0 >100 >100 3B BC 118.9 1:160 144.8 4.49 >100 3A PR 8.8 Neg 3.8 49.7 81.5 1 MA 124.0 1:80 128.4 82.9 3B-C SM 130.6 1:320 125.2 3C PA 105.8 1:320 126.7 >100 >100 3C

*AGA IgA vn <10, borderline 8-15, positivo > 15

NOS ANA Neurone DRG Neg Neg CNS+ IS Neg Cito+ Neg BC R1 Neg Neg PR Neg Neg Neg MA R1 ANAs Neg SM R1 Cito+ Neg PA Neg Neg Neg

Controlli sesso: 3 F e 3 M

età: range 12 - 28 mesipatologie: neurologiche, polmonari, F-U soggetti

asintomatici per infezioni peri-natali

AGA IgA vn <10, borderline 8-15, positivo > 15

Tutti i marker di celiachia e altri auto-anticorpi negativi, solo un caso di AGA IgA borderline (6.8)

Adattato da Basso, D. et al. Clin Chem 2009;55:150-157

Sensitivity Specificity PPV NPV

≤ 2 anni

AGA IgA II 80.0 93.8 96.0 71.4

AGA IgG II 96.7 100 100 94.1

tTG IgA 90 100 100 84.2

Change in DGP antibodies and TGAA in children receiving GFD vs regular dietLiu, Edwin et al JPGN 2007

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Top, In children treated with GFD, DGP antibody levels significantly decreased (most resolved); however, children receiving a regular diet had persistently high levels of DGP antibodies. Bottom, TGAA levels also decreased significantly with GFD treatment, compared with children receiving a regular diet; however, the majority of children treated with GFD remained TGAA positive.

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Liu, Edwin et al JPGN 2007

Liu, Edwin et al JPGN 2007Representative graphs of children treated with GFD over time. Arrow indicates time of biopsy with confirmed celiac disease, and institution of GFD. Sometimes, rarely, and never indicate patient-reported frequency of dietary indiscretion. A, Example of persistently positive TGAA with resolution of DGP antibodies. B, Example of transiently positive TGAA while DGP remained negative at all time points. C, Example of persistently positive TGAA and DGP antibodies. D, Example of complete resolution of both TGAA and DGP antibodies.

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Solid line = DGP antibody, dashed line = TGAA

Gliadina Deamidata (DGP)

• L’anticorpo di classe IgG (IgG DGP) è la vera novità

• In aggiunta alle tTG aumenta la nostra capacità diagnostica

• IgG DGP:– Può essere impiegato nei deficit di IgA– Può essere impiegato sotto i due anni di età– Permette una conferma diagnostica e aumenta

la specificità dei due test combinati• IgG DGP è un marcatore più tempestivo della

aderenza alla dieta aglutinata

Possibile variazione iter diagnostico sierologico

IgA tTG IgA tTG

IgA EMA

IgG tTG

IgA AGA IgG DGP

Adattato da Volta et al. Expert Rev Gastroenterol Hepatol 2010