MCAD defekt; en lang rejse

Transkript

1 MCAD defekt; en lang rejse Niels Gregersen Molekylær Medicinsk Forskningsenhed Klinisk Institut, Aarhus Universitet og Århus Universitetshospital, Skejby VLCAD EH HDH KT TFP MCAD SCAD LCAD EH HDH KT

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3 MCAD defekt: En defekt i omsætningen af fede syrer

4 Urinundersøgelse for organiske syrer ved gaskromatografi-massespektrometri (GC-MS) 2-årig dreng 3. anfald Døsighed udviklet til bevistløshed Hypoketotisk hypoglykæmi Acidose Forhøjede leverenzymer Seks anfald i alderen 2, 20, 25, 27, 28 og 30 mdr. GC-MS urinundersøgelse Mælkesyre β-hydroxy smørsyre Adipinsyre Suberinsyre Suberylglycin Sebacinsyre

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6 Fedtsyreoxidationen (β-oxidationen) i mitokondrierne

7 Fedtsyreoxidationen (β-oxidationen) LK-fedt acyl-coa VLCAD Dekanoyl-CoA MCAD Oktanoyl-CoA MCAD Hexanoyl-CoA MCAD Butyryl-CoA SCAD Acetyl-CoA Sebacinsyre Suberinsyre Adipinsyre Suberylglycin Citronsyrecyklus

8 Metabolitter ved MCAD mangel LC-fatty acyl-coa VLCAD Decanoyl-CoA MCAD Octanoyl-CoA MCAD Hexanoyl-CoA MCAD Butyryl-CoA SCAD Acetyl-CoA Citric acid cycle Decanoylcarnitine Decenoylcarnitine Octanoylcarnitine Hexanoylcarnitine Hexanoylglycine Sebacinsyre Suberinsyre Adipinsyre Suberylglycin

9 Tandem masssespektrometri af acylcarnitiner i blod fra patient med MCAD mangel

10 Fra patient til gen og tilbage Urin metabolitter Kliniske symptomer hos patienten Unormale metabolitter i urin og blod Nedsat enzymaktivitet ACAD aktivitet Kontrol Patient Mutation i gen 1990 C6 C8 C10 MCAD gensekventering A C G T A C G T Patient Kontrol

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12 PCR 94 C 5min 22 C 1min 53 C 6min

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15 MCAD genet 985A>G ATG 5 -UTR UTR

16 Fatty acid oxidation workshop. Sandbjerg May 1990 Matsubara Y, Narisawa K, Miyabayashi S, Tada K, Coates PM, Bachmann C, ElsasLJ, Pollitt RJ, Rhead WM, Roe CR. Biochem Biophys Res Comm 171; 1990: Gregersen N, Andresen BS, Bross P, Winter V, Rüdiger N, Engst S, Christensen E, Kelly D, Strauss AW, Kølvraa S, Bolund L, Ghisla S. Hum Genet 86; 1991: Yokota I, Indo Y, Coates PM, Tanaka K. J Clin Invest 86;1990: A C G T A C G T Kelly DP, Whelan AJ, Ogden ML, Alpers R, Zhang ZF, Bellus G, Gregersen N, Dorland L, Strauss AW.. Proc Natl Acad Sci (USA ) 87, 1990: Patient Control 985A>G

17 MCAD deficiency 985A>G prevalence: Philadelphia 1991 Genotypering af 172 patienter med MCAD defekt for 985A>G Total G/G G/non-G non-g/non-g % 18% 2% Coates PM, Chen YT, Curtis D, Gregersen N, et al. Prog Clin Biol Res 1992; 375: Tanaka K, Yokota I, Coates PM, Strauss AW, Kelly DP, Zhang Z, Gregersen N, Andresen BS, Matsubara Y, Curtis D, Chen YT. Hum Mut 1;

18 Translatorisk medicin cyklus Treatment Clinical, Biochemical and/or genetic tests Patients Molecular cell pathology Indications of genes involved Cell and animal models Molecular genetic investigations Identification of gene variations Molecular pathogenesis Gene variation(s) Functional studies

19 Diagnostisk strategi ved mistanke om MCAD defekt Patient Clinical symptoms Urine/blood abnormalities 80% 20% 985G assay 985G/985G Family study Diagnosis confirmed Heterozygous 985G or non 985G MCAD gene sequencing 985G/X or X/Y Family study Diagnosis confirmed

20 Genetisk Diagnostik Genotypering af 985A>G MCAD mutationen A/A G/A A/A G/A G/A G/A A/A G/A G/G G/G A/A

21 Diagnostisk brug af variationsspecifikt assay MCAD 985A>G A/A G/A A/A G/A G/A G/A G/A G/G G/G A/A

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25 Diagnostisk sekventering af exon 11 Kontrol Heterozygot Homozygot

26 Mild og alvorlig MCAD gene variation?? G/A X/A G: 985A>G A: normal X: mild variation 558T>A? G/X Fundet ved screening efter nedsættelse af cut-off G/X Fundet ved screening ved normal cut-off.

27 Translatorisk medicin cyklus Treatment Clinical, Biochemical and/or genetic tests Patients Molecular cell pathology Indications of genes involved Cell and animal models Molecular genetic investigations Identification of gene variations Molecular pathogenesis Gene variation(s) Functional studies

28 Fra patient til gen og tilbage Urin metabolitter Kliniske symptomer hos patienten Unormale metabolitter i urin og blod Nedsat enzymaktivitet ACAD aktivitet Kontrol Patient Mutation i gen 1990 C6 C8 C10 MCAD gensekventering A C G T A C G T Genfrekvens 1991 Patient Kontrol

29 Frequency of MCAD 985A>G 1:127 1:50 USA 1:84 1:276 1:102 Disease frequency: 1/30000 Japan 0 1:83 1:64 1:62 1:98 1:76 1:104 1:52 1:115 1:240 1:218 1:91 1:215 1:142 1:332 Australia 1:71 Tanaka K, Gregersen N, et al. Pediat Res 1997;41:

30 Fra patient til gen og tilbage Urin metabolitter Kliniske symptomer hos patienten Unormale metabolitter i urin og blod Nedsat enzymaktivitet ACAD aktivitet Kontrol Patient Mutation i gen 1990 C6 C8 C10 MCAD gensekventering A C G T A C G T Genfrekvens 1991 Patient Blodmetabolitter Kontrol Screening af nyfødte 2002

31 Translatorisk medicins cyklus Treatment Clinical, Biochemical and/or genetic tests Patients Molecular cell pathology Indications of genes involved Cell and animal models Molecular genetic investigations Identification of gene variations Molecular pathogenesis Gene variation(s) Functional studies

32 MCAD missense mutationer

33 Sterically Forbidden Mutation G170R

34 Wildtype - No Steric Strain

35 Mutation kcal / mol No optimization

36 Mutation kcal / mol Full optimization

37 LC-fatty acyl-coa VLCAD Decanoyl-CoA MCAD Octanoyl-CoA MCAD Hexanoyl-CoA MCAD Butyryl-CoA SCAD Acetyl-CoA Citric acid cycle Oktansyre R147W G185S W153R A168V G66C G68C R22W R83C S329L R359C R356W R301W N C R147W G185S W153R A168V G66C G68C R22W R83C S329L R359C R356W R301W N C Energi mangel Sygdomsmekanisme ved MCAD mangel Loss-of-function Gain-offunction R147W G185S W153R A168V G66C G68C R22W R83C S329L R359C R356W R301W N C R147W G185S W153R A168V G66C G68C R22W R83C S329L R359C R356W R301W N C Nedbrydning Ophobning

38 MCAD Protein (Western blot med anti-mcad antistof) 1989

39 Fedtsyreoxidationen (β-oxidationen) i mitokondrierne

40 Fedtsyreoxidationen (β-oxidationen) i mitokondrierne VLCAD TFP LCAD MCAD EH HDH KT SCAD EH HDH KT VLCAD TFP LCAD VLCAD TFP LCAD MCAD HDH EH KT SCAD EH KT HDH HDH EH KT SCAD EH KT HDH

41 MCAD Mangel Grunden til den store variation i alvorligheden af sygdommen kenden vi ikke i dag. Det måskyldes andre genetiske variationer og ydre påvirkninger, såsom feber og stess. Det er det vi prøver at finde ud af. VLCAD TFP LCAD MCAD EH HDH KT SCAD EH HDH KT

42 Rinaldo, Matern, Bennett. Annu. Rev. Physiol. 2002; 64: C 16 -C 18 fatty acids Long-Chain Fatty Acid Transporter VLCAD 1 2 C 18 Enoyl-CoA H 2 O Acyl-CoA C 16 Carnitine Acyl-CoA Carnitine Transporter C 14 C 12 β-oh acyl-coa NAD + 3 NADH+H + TFP β-ketoacyl-coa 4 Carnitine -CH=CH- -CH-CH 2 - OH Acetyl-CoA 2 Carnitine CPT I CoASH CoASH MCAD SCAD 3 1 Acylcarnitine Acylcarnitine FAD + FADH FAD + 2 FADH 2 H 2 O CPT II NAD + Acyl-CoA -CH 2 -CH 2-4 -C-CH 2 - = O NADH+H + CACT Carnitine C 4 -C 12 fatty acids Carnitine Steroidogenesis Acetyl-CoA Ketogenesis TCA cycle ATP FADH 2 FAD + NADH+H + IMM ADP+P i H + 1/2 O 2 H + H 2 O H + NAD + II V IV III I CoQ Plasma membrane Cyt c H + H + H + OMM

43 Rinaldo, Matern, Bennett. Annu. Rev. Physiol. 2002; 64: C 16 -C 18 fatty acids Long-Chain Fatty Acid Transporter VLCAD 1 2 C 18 Enoyl-CoA H 2 O Acyl-CoA C 16 Carnitine Acyl-CoA Carnitine Transporter C 14 C 12 β-oh acyl-coa NAD + 3 NADH+H + TFP β-ketoacyl-coa 4 Carnitine -CH=CH- -CH-CH 2 - OH Acetyl-CoA 2 Carnitine CPT I CoASH CoASH MCAD SCAD 3 1 Acylcarnitine Acylcarnitine FAD + FADH FAD + 2 FADH 2 H 2 O CPT II NAD + Acyl-CoA -CH 2 -CH 2-4 -C-CH 2 - = O NADH+H + CACT Carnitine C 4 -C 12 fatty acids Carnitine Steroidogenesis Acetyl-CoA Ketogenesis TCA cycle ATP FADH 2 FAD + NADH+H + IMM ADP+P i H + 1/2 O 2 H + H 2 O H + NAD + II V IV III I CoQ Plasma membrane Cyt c H + H + H + OMM

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