Maple Syrup Urine Disease (MSUD)Maple Syrup Urine Disease (MSUD)By Jenny Morrison (836445)By Jenny Morrison (836445)

Deficiency in branched chain Deficiency in branched chain alpha-keto acid alpha-keto acid dehydrogenase complex dehydrogenase complex (BCKAD) – located in (BCKAD) – located in mitochondrial inner membranemitochondrial inner membrane

Caused by mutation in 4 Caused by mutation in 4 possible genes BCKDHA, possible genes BCKDHA, BCKDHB, DBT, and DLD that BCKDHB, DBT, and DLD that encode for the BCKADencode for the BCKAD

Results in defect in Results in defect in metabolism of branched chain metabolism of branched chain amino acids (BCAA): Valine, amino acids (BCAA): Valine, Leucine and Isoleucine Leucine and Isoleucine

Accumulation of BCAA and Accumulation of BCAA and their keto acid derivativestheir keto acid derivatives

5 clinical subtypes: “classic” 5 clinical subtypes: “classic” “intermittent”, “mild”, Thiamine “intermittent”, “mild”, Thiamine responsive, and E3-deficient responsive, and E3-deficient with lactic acidosis.with lactic acidosis.

Classification of subtypes Classification of subtypes according to nature of gene according to nature of gene mutation by genetic mutation by genetic complementation analysis after complementation analysis after somatic cell hybridisation somatic cell hybridisation (1980)(1980)

Classic MSUD is the most Classic MSUD is the most severe and most common formsevere and most common form

4 of the MSUD 4 of the MSUD clinical subtypesclinical subtypes

Onset in the first week of life:Onset in the first week of life: Maple syrup odour (in urineMaple syrup odour (in urine and on body)and on body) Feeding difficulties andFeeding difficulties and vomitingvomiting Shrill cryShrill cry Hypertonicity (episodesHypertonicity (episodes alternate with flaccidity)alternate with flaccidity) No Moro reflex and No Moro reflex and suppressed deep tendonsuppressed deep tendon reflexesreflexes Frequent convulsionsFrequent convulsions Survivors suffer from severeSurvivors suffer from severe mental retardation & motormental retardation & motor development retardationdevelopment retardation

Symptoms – Symptoms – “classic” MSUD“classic” MSUD

(Bondy & Rosenberg, 1980)

InheritanceInheritance Autosomal recessiveAutosomal recessive Frequency: Frequency:

1 in 185,000 newborns world wide (Chuang et al, 1995) 1 in 185,000 newborns world wide (Chuang et al, 1995) 1 in 176 newborns in the Mennonite population of Lancaster, 1 in 176 newborns in the Mennonite population of Lancaster,

Pennsylvania (due to consanguinity)Pennsylvania (due to consanguinity) Panethnic distributionPanethnic distribution

Genetic CounsellingGenetic Counselling Relatives of the affected individual have high genetic risks (1 in 4)Relatives of the affected individual have high genetic risks (1 in 4)

Extremely low risks to offsprings of healthy sibs or more distantExtremely low risks to offsprings of healthy sibs or more distant

relatives relatives

Molecular genetics of the BCKADMolecular genetics of the BCKAD

Molecular Molecular PhenotypesPhenotypes

GenesGenes ChromosomeChromosome ExonsExons T’scriptT’script

lengthlength

T’slationT’slation

LengthLength

IAIA E1E1ααBCKDHABCKDHA

19q13.1 – 13.219q13.1 – 13.2 99 13521352 445445

IBIB E1E1ββBCKDHBBCKDHB

6p21 – p226p21 – p22 1010 11791179 392392

IIII E2E2DBTDBT

1p311p31 1111 23842384 482482

IIIIII E3E3DLDDLD

7q31 - 327q31 - 32 1414 23202320 509509

each molecular phenotype can have > 1 clinical phenotype as different mutations in the same subunit may have different effects on the stability and function of the polypeptide.

MSUD type II constitute the majority of mutations reported

MSUD Type IAMSUD Type IA

ExonExon CodonCodon MutationMutation ConsequenceConsequence

99 393393 TTAC AC → → AAACAC Tyr Tyr → Asn→ Asn

77 242242 8-bp deletion8-bp deletion FrameshiftFrameshift

99 368368 TTAAT T → T→ TGGTT Tyr Tyr → Cys→ Cys

22 44 CAG CAG → C→ CCCAGAG FrameshiftFrameshift

66 222222 AAAAT T → A→ AGGTT Asn Asn → Ser→ Ser

E1α

Protein SequenceProtein SequenceMAVAIAAARVWRLNRGLSQAALLLLRQPGARGLARSHMAVAIAAARVWRLNRGLSQAALLLLRQPGARGLARSHPPRQQQQFSSLDDKPQFPGASAEFIDKLEFIQPNVISGIPPRQQQQFSSLDDKPQFPGASAEFIDKLEFIQPNVISGIPIYRVMDRQGQIINPSEDPHLPKEKVLKLYKSMTLLNTPIYRVMDRQGQIINPSEDPHLPKEKVLKLYKSMTLLNTMDRILYESQRQGRISFYMTNYGEEGTHVGSAAALDNTMDRILYESQRQGRISFYMTNYGEEGTHVGSAAALDNTDLVFGQYREAGVLMYRDYPLELFMAQCYGNISDLGKGDLVFGQYREAGVLMYRDYPLELFMAQCYGNISDLGKGRQMPVHYGCKERHFVTISSPLATQIPQAVGAAYAAKRRQMPVHYGCKERHFVTISSPLATQIPQAVGAAYAAKRANANRVVICYFGEGAASEGDAHAGFNFAATLECPIIFFANANRVVICYFGEGAASEGDAHAGFNFAATLECPIIFFCRNNGYAISTPTSEQYRGDGIAARGPGYGIMSIRVDGCRNNGYAISTPTSEQYRGDGIAARGPGYGIMSIRVDGNDVFAVYNATKEARRRAVAENQPFLIEAMTYRIGHHSTNDVFAVYNATKEARRRAVAENQPFLIEAMTYRIGHHSTSDDSSAYRSVDEVNYWDKQDHPISRLRHYLLSQGWWSDDSSAYRSVDEVNYWDKQDHPISRLRHYLLSQGWWDEEQEKAWRKQSRRKVMEAFEQAERKPKPNPNLLFSDEEQEKAWRKQSRRKVMEAFEQAERKPKPNPNLLFSDVYQEMPAQLRKQQESLARHLQTYGEHYPLDHFDKDVYQEMPAQLRKQQESLARHLQTYGEHYPLDHFDK

mRNA sequencemRNA sequence

1 gccggaccgc tgagtggttg ttagccaaga tggcggtagc gatcgctgca gcgagggtct 1 gccggaccgc tgagtggttg ttagccaaga tggcggtagc gatcgctgca gcgagggtct

61 ggcggctaaa ccgtggtttg agccaggctg ccctcctgct gctgcggcag cctggggctc 61 ggcggctaaa ccgtggtttg agccaggctg ccctcctgct gctgcggcag cctggggctc

121 ggggactggc tagatctcac ccccccaggc agcagcagca gttttcatct ctggatgaca 121 ggggactggc tagatctcac ccccccaggc agcagcagca gttttcatct ctggatgaca

181 agccccagtt cccaggggcc tcggcggagt ttatagataa gttggaattc atccagccca 181 agccccagtt cccaggggcc tcggcggagt ttatagataa gttggaattc atccagccca

241 acgtcatctc tggaatcccc atctaccgcg tcatggaccg gcaaggccag atcatcaacc 241 acgtcatctc tggaatcccc atctaccgcg tcatggaccg gcaaggccag atcatcaacc

301 ccagcgagga cccccacctg ccgaaggaga aggtgctgaa gctctacaag agcatgacac 301 ccagcgagga cccccacctg ccgaaggaga aggtgctgaa gctctacaag agcatgacac

361tgcttaacac catggaccgc atcctctatg agtctcagcg gcagggccgg atctccttct 361tgcttaacac catggaccgc atcctctatg agtctcagcg gcagggccgg atctccttct

421acatgaccaa ctatggtgag gagggcacgc acgtggggag tgccgccgcc ctggacaaca 421acatgaccaa ctatggtgag gagggcacgc acgtggggag tgccgccgcc ctggacaaca

481 cggacctggt gtttggccag taccgggagg caggtgtgct gatgtatcgg gactaccccc 481 cggacctggt gtttggccag taccgggagg caggtgtgct gatgtatcgg gactaccccc

541tggaactatt catggcccag tgctatggca acatcagtga cttgggcaag gggcgccaga 541tggaactatt catggcccag tgctatggca acatcagtga cttgggcaag gggcgccaga

601tgcctgtcca ctacggctgc aaggaacgcc acttcgtcac tatctcctct ccactggcca 601tgcctgtcca ctacggctgc aaggaacgcc acttcgtcac tatctcctct ccactggcca

661cgcagatccc tcaggcggtg ggggcggcgt acgcagccaa gcgggccaat gccaacaggg 661cgcagatccc tcaggcggtg ggggcggcgt acgcagccaa gcgggccaat gccaacaggg

721tcgtcatctg ttacttcggc gagggggcag ccagtgaggg ggacgcccat gccggcttca 721tcgtcatctg ttacttcggc gagggggcag ccagtgaggg ggacgcccat gccggcttca

781acttcgctgc cacacttgag tgccccatca tcttcttctg ccggaacaat ggctacgcca 781acttcgctgc cacacttgag tgccccatca tcttcttctg ccggaacaat ggctacgcca

841tctccacgcc cacctctgag cagtatcgcg gcgatggcat tgcagcacga ggccccgggt 841tctccacgcc cacctctgag cagtatcgcg gcgatggcat tgcagcacga ggccccgggt

901atggcatcat gtcaatccgc gtggatggta atgatgtgtt tgccgtatac aacgccacaa 901atggcatcat gtcaatccgc gtggatggta atgatgtgtt tgccgtatac aacgccacaa

961aggaggcccg acggcgggct gtggcagaga accagccctt cctcatcgag gccatgacct 961aggaggcccg acggcgggct gtggcagaga accagccctt cctcatcgag gccatgacct

1021acaggatcgg gcaccacagc accagtgacg acagttcagc gtaccgctcg gtggatgagg 1021acaggatcgg gcaccacagc accagtgacg acagttcagc gtaccgctcg gtggatgagg

1081tcaattactg ggataaacag gaccacccca tctcccggct gcggcactat ctgctgagcc 1081tcaattactg ggataaacag gaccacccca tctcccggct gcggcactat ctgctgagcc

1141aaggctggtg ggatgaggag caggagaagg cctggaggaa gcagtcccgc aggaaggtga 1141aaggctggtg ggatgaggag caggagaagg cctggaggaa gcagtcccgc aggaaggtga

1201tggaggcctt tgagcaggcc gagcggaagc ccaaacccaa ccccaaccta ctcttctcag 1201tggaggcctt tgagcaggcc gagcggaagc ccaaacccaa ccccaaccta ctcttctcag

1261acgtgtatca ggagatgccc gcccagctcc gcaagcagca ggagtctctg gcccgccacc 1261acgtgtatca ggagatgccc gcccagctcc gcaagcagca ggagtctctg gcccgccacc

1321tgcagaccta cggggagcac tacccactgg atcacttcga taagtgagac ctgctcagcc 1321tgcagaccta cggggagcac tacccactgg atcacttcga taagtgagac ctgctcagcc

1381cacccccacc catcctcagc taccccgaga ggtagcccca ctctaagggg agcaggggga 1381cacccccacc catcctcagc taccccgaga ggtagcccca ctctaagggg agcaggggga

1441cctgacagca caccactgtc ttccccagtc agctccctct aaaatactca gcggccaggg 1441cctgacagca caccactgtc ttccccagtc agctccctct aaaatactca gcggccaggg

1501cggctgccac tcttcacccc tgctcctccc ggctgttaca ttgtcagggg acagcatctg 1501cggctgccac tcttcacccc tgctcctccc ggctgttaca ttgtcagggg acagcatctg

1561cagcagttgc tgaggctccg tcagccccct cttcacctgt tgttacagtg ccttctccca 1561cagcagttgc tgaggctccg tcagccccct cttcacctgt tgttacagtg ccttctccca

1621ggggctgggt gagggcacat tcaggactag aagcccctct gggcatgggg tggacatggc 1621ggggctgggt gagggcacat tcaggactag aagcccctct gggcatgggg tggacatggc

1681aggtcagcct gtggaacttg cgcaggtgcg agtggccagc agaggtcacg aataaactgc 1681aggtcagcct gtggaacttg cgcaggtgcg agtggccagc agaggtcacg aataaactgc

1741atctctgcgc ctggctctct accaaaaaaa aaaaaaaaaa a1741atctctgcgc ctggctctct accaaaaaaa aaaaaaaaaa a

MSUD Type IBMSUD Type IB

Exon Exon MutationMutation ConsequenceConsequence

11 11-bp deletion11-bp deletion frameshiftframeshift

E1β

Protein sequenceMAVVAAAAGWLLRLRAAGAEGHWRRLPGAGLARGFLHPAATVEDAAQRRQVAHFTFQPDPEPREYGQTQKMNLFQSVTSALDNSLAKDPTAVIFGEDVAFGGVFRCTVGLRDKYGKDRVFNTPLCEQGIVGFGIGIAVTGATAIAEIQFADYIFPAFDQIVNEAAKYRYRSGDLFNCGSLTIRSPWGCVGHGALYHSQSPEAFFAHCPGIKVVIPRSPFQAKGLLLSCIEDKNPCIFFEPKILYRAAAEEVPIEPYNIPLSQAEVIQEGSDVTLVAWGTQVHVIREVASMAKEKLGVSCEVIDLRTIIPWDVDTICKSVIKTGRLLISHEAPLTGGFASEISSTVQEECFLNLEAPISRVCGYDTPFPHIFEPFYIPDKWKCYDALRKMINY

Alternate splicing results in 2 transcripts that encode the same protein

mRNA transcript variant 2

1 aggcggcgtg cggctgcata gcctgagaat cccggtggtg agcggggatg gcggttgtag

61 cggcggctgc cggctggcta ctcaggctca gggcggcagg ggctgagggg cactggcgtc

121 ggcttcctgg cgcggggctg gcgcggggct ttttgcaccc cgccgcgact gtcgaggatg

181 cggcccagag gcggcaggtg gctcatttta ctttccagcc agatccggag ccccgggagt

241 acgggcaaac tcagaaaatg aatcttttcc agtctgtaac aagtgccttg gataactcat

301 tggccaaaga tcctactgca gtaatatttg gtgaagatgt tgcctttggt ggagtcttta

361 gatgcactgt tggcttgcga gacaaatatg gaaaagatag agtttttaat accccattgt

421 gtgaacaagg aattgttgga tttggaatcg gaattgcggt cactggagct actgccattg

481 cggaaattca gtttgcagat tatattttcc ctgcatttga tcagattgtt aatgaagctg

541 ccaagtatcg ctatcgctct ggggatcttt ttaactgtgg aagcctcact atccggtccc

601 cttggggctg tgttggtcat ggggctctct atcattctca gagtcctgaa gcattttttg

661 cccattgccc aggaatcaag gtggttatac ccagaagccc tttccaggcc aaaggacttc

721 ttttgtcatg catagaggat aaaaatcctt gtatattttt tgaacctaaa atactttaca

781 gggcagcagc ggaagaagtc cctatagaac catacaacat cccactgtcc caggccgaag

841 tcatacagga agggagtgat gttactctag ttgcctgggg cactcaggtt catgtgatcc

901 gagaggtagc ttccatggca aaagaaaagc ttggagtgtc ttgtgaagtc attgatctga

961 ggactataat accttgggat gtggacacaa tttgtaagtc tgtgatcaaa acagggcgac

1021 tgctaatcag tcacgaggct cccttgacag gcggctttgc atcggaaatc agctctacag

1081 ttcaggagga atgtttcttg aacctagagg ctcctatatc aagagtatgt ggttatgaca

1141 caccatttcc tcacattttt gaaccattct acatcccaga caaatggaag tgttatgatg

1201 cccttcgaaa aatgatcaac tattgaccat atagaaaagc tggaagatta tgactagata

1261 tggaaatatt ttttctgaat ttttttttat atttcctccg acttacctct ttttgaaaag

1321 agagttttta ttaaatgaac catcatgata ttggctgaaa agttctacat tctattattg

1381 tattgtaaca cacatgtatt gatgattttc attaagagtt tcagattaac tttgaaaaat

1441 attccacatg gtaatcttat aaattctgtt taattacatc tgtaaatatt atgtgtgtga

1501 tagtattcaa taaagtaaaa tcaaattgtc aaaaaaaaaa aaaaaaaaaa aa//

MSUD Type IB cont.MSUD Type IB cont.mRNA transcript variant 1mRNA transcript variant 1

1 aggcggcgtg cggctgcata gcctgagaat cccggtggtg agcggggatg gcggttgtag 1 aggcggcgtg cggctgcata gcctgagaat cccggtggtg agcggggatg gcggttgtag

61 cggcggctgc cggctggcta ctcaggctca gggcggcagg ggctgagggg cactggcgtc 61 cggcggctgc cggctggcta ctcaggctca gggcggcagg ggctgagggg cactggcgtc

121 ggcttcctgg cgcggggctg gcgcggggct ttttgcaccc cgccgcgact gtcgaggatg 121 ggcttcctgg cgcggggctg gcgcggggct ttttgcaccc cgccgcgact gtcgaggatg

181 cggcccagag gcggcaggtg gctcatttta ctttccagcc agatccggag ccccgggagt 181 cggcccagag gcggcaggtg gctcatttta ctttccagcc agatccggag ccccgggagt

241 acgggcaaac tcagaaaatg aatcttttcc agtctgtaac aagtgccttg gataactcat 241 acgggcaaac tcagaaaatg aatcttttcc agtctgtaac aagtgccttg gataactcat

301 tggccaaaga tcctactgca gtaatatttg gtgaagatgt tgcctttggt ggagtcttta 301 tggccaaaga tcctactgca gtaatatttg gtgaagatgt tgcctttggt ggagtcttta

361 gatgcactgt tggcttgcga gacaaatatg gaaaagatag agtttttaat accccattgt 361 gatgcactgt tggcttgcga gacaaatatg gaaaagatag agtttttaat accccattgt

421 gtgaacaagg aattgttgga tttggaatcg gaattgcggt cactggagct actgccattg 421 gtgaacaagg aattgttgga tttggaatcg gaattgcggt cactggagct actgccattg

481 cggaaattca gtttgcagat tatattttcc ctgcatttga tcagattgtt aatgaagctg 481 cggaaattca gtttgcagat tatattttcc ctgcatttga tcagattgtt aatgaagctg

541 ccaagtatcg ctatcgctct ggggatcttt ttaactgtgg aagcctcact atccggtccc 541 ccaagtatcg ctatcgctct ggggatcttt ttaactgtgg aagcctcact atccggtccc

601 cttggggctg tgttggtcat ggggctctct atcattctca gagtcctgaa gcattttttg 601 cttggggctg tgttggtcat ggggctctct atcattctca gagtcctgaa gcattttttg

661 cccattgccc aggaatcaag gtggttatac ccagaagccc tttccaggcc aaaggacttc 661 cccattgccc aggaatcaag gtggttatac ccagaagccc tttccaggcc aaaggacttc

721 ttttgtcatg catagaggat aaaaatcctt gtatattttt tgaacctaaa atactttaca 721 ttttgtcatg catagaggat aaaaatcctt gtatattttt tgaacctaaa atactttaca

781 gggcagcagc ggaagaagtc cctatagaac catacaacat cccactgtcc caggccgaag 781 gggcagcagc ggaagaagtc cctatagaac catacaacat cccactgtcc caggccgaag

841 tcatacagga agggagtgat gttactctag ttgcctgggg cactcaggtt catgtgatcc841 tcatacagga agggagtgat gttactctag ttgcctgggg cactcaggtt catgtgatcc

901 gagaggtagc ttccatggca aaagaaaagc ttggagtgtc ttgtgaagtc attgatctga 901 gagaggtagc ttccatggca aaagaaaagc ttggagtgtc ttgtgaagtc attgatctga

961 ggactataat accttgggat gtggacacaa tttgtaagtc tgtgatcaaa acagggcgac961 ggactataat accttgggat gtggacacaa tttgtaagtc tgtgatcaaa acagggcgac

1021 tgctaatcag tcacgaggct cccttgacag gcggctttgc atcggaaatc agctctacag1021 tgctaatcag tcacgaggct cccttgacag gcggctttgc atcggaaatc agctctacag

1081 ttcaggagga atgtttcttg aacctagagg ctcctatatc aagagtatgt ggttatgaca1081 ttcaggagga atgtttcttg aacctagagg ctcctatatc aagagtatgt ggttatgaca

1141 caccatttcc tcacattttt gaaccattct acatcccaga caaatggaag tgttatgatg1141 caccatttcc tcacattttt gaaccattct acatcccaga caaatggaag tgttatgatg

1201 cccttcgaaa aatgatcaac tattgaccat ataggtaggt atgcatcttg agaaagctac1201 cccttcgaaa aatgatcaac tattgaccat ataggtaggt atgcatcttg agaaagctac

1261 tatgtgcccc tgacattaac gtactgttaa ccaagacaca gcaatcatca gtgttttgat1261 tatgtgcccc tgacattaac gtactgttaa ccaagacaca gcaatcatca gtgttttgat

1321 ggtaacaaac tttgatggta aagttgataa aaggcaactt tcagaagaaa ataatgtgct1321 ggtaacaaac tttgatggta aagttgataa aaggcaactt tcagaagaaa ataatgtgct

1381 ttagaaaaaa aattcaaatt tatagtagta tatttacatt tttgttgttg ttgttctgag1381 ttagaaaaaa aattcaaatt tatagtagta tatttacatt tttgttgttg ttgttctgag

1441 atggagtctc actctgtcgc ccaggctaga ctgcagtggt gcaatctcag ctcactgcaa1441 atggagtctc actctgtcgc ccaggctaga ctgcagtggt gcaatctcag ctcactgcaa

1501 cctcccccct acccccgagt tcaagcaatt ctcctgcctc agcctgctga gtagttggga 1501 cctcccccct acccccgagt tcaagcaatt ctcctgcctc agcctgctga gtagttggga

1561 ttacaggtgc ccaccaccat gcccagctaa tttttgtgtt tttattggag gtggggtttc1561 ttacaggtgc ccaccaccat gcccagctaa tttttgtgtt tttattggag gtggggtttc

1621 actatgttgg ctcagctgat ttcaaattcc tgacctcaag tgatccacct gccttagcct1621 actatgttgg ctcagctgat ttcaaattcc tgacctcaag tgatccacct gccttagcct

1681 cccaaagtgc tgggattaca ggcatgagcc actgcacctg gctatattta catttaatag1681 cccaaagtgc tgggattaca ggcatgagcc actgcacctg gctatattta catttaatag

1741 aaacatatct agcatatgta tatgtgattt tttttttttt tgagaccgag tctcactctg1741 aaacatatct agcatatgta tatgtgattt tttttttttt tgagaccgag tctcactctg

1801 tcaccaggct ggagtgcagt ggtgcgatct tggctcatgg caacctccgc ctcccaggtt1801 tcaccaggct ggagtgcagt ggtgcgatct tggctcatgg caacctccgc ctcccaggtt

1861 caagcgattg tcctgcctca gtctcctgag tagctgggac tacaggtgtg caccaacatg1861 caagcgattg tcctgcctca gtctcctgag tagctgggac tacaggtgtg caccaacatg

1921 cccagctaat tttttatatt tttagtagag acggggtttc accatgttgg ccaggatggt1921 cccagctaat tttttatatt tttagtagag acggggtttc accatgttgg ccaggatggt

1981 ctcgatctct tgaccttgtg ttccacccgt cttggcctcc caaagcgctg gaattacagg1981 ctcgatctct tgaccttgtg ttccacccgt cttggcctcc caaagcgctg gaattacagg

2041 catgagccac cgcgcctggc ctgtatatgt gatttctaaa aaatagatgc atgcatatgt2041 catgagccac cgcgcctggc ctgtatatgt gatttctaaa aaatagatgc atgcatatgt

2101 taacattgaa tagtcaatca ctagatgaag atgctctcta ccatggttta gattgcaagt2101 taacattgaa tagtcaatca ctagatgaag atgctctcta ccatggttta gattgcaagt

2161 gtactttata ccattgtttc aacttcaacc tttatttttg tatatatttt ttcaactact2161 gtactttata ccattgtttc aacttcaacc tttatttttg tatatatttt ttcaactact

2221 taaactgttc atgaataggc gtactttctg tatttaaaaa tggcccctca agcaccgtta 2221 taaactgttc atgaataggc gtactttctg tatttaaaaa tggcccctca agcaccgtta

2281 atttacattc cagttattta catgataatt catgacattc tgaaacttgc ctgtatatta 2281 atttacattc cagttattta catgataatt catgacattc tgaaacttgc ctgtatatta 2341 tctgaaaaat ggatttcttg aggaaaagat ctgtttattg tatgtaagga aaaattttac 2341 tctgaaaaat ggatttcttg aggaaaagat ctgtttattg tatgtaagga aaaattttac 2401 ctgaaaacaa acaaacaaac cctaaaactc agcaccacta ccatttccag aagctttttt 2401 ctgaaaacaa acaaacaaac cctaaaactc agcaccacta ccatttccag aagctttttt 2461 agcaagtgaa tattttttac ataatggata ataaatggta tttattcatc atgattttct 2461 agcaagtgaa tattttttac ataatggata ataaatggta tttattcatc atgattttct 2521 aagtaatgct tatcagcccc ttcagtggtg ttattctaac aaaatgaata cattacaaat 2521 aagtaatgct tatcagcccc ttcagtggtg ttattctaac aaaatgaata cattacaaat 2581 tattaagtta gcttttcaga gttttaatat agaagttact agcactgaca cactgatttt 2581 tattaagtta gcttttcaga gttttaatat agaagttact agcactgaca cactgatttt 2641 gaaatgtttc aaaatgagta gatacgatta gatcctttac cttttaatat ctagtttttc 2641 gaaatgtttc aaaatgagta gatacgatta gatcctttac cttttaatat ctagtttttc 2701 caaaaatgat agtaatatct tttgaagaac tatgcttttt caaaagcaaa atcaactctg 2701 caaaaatgat agtaatatct tttgaagaac tatgcttttt caaaagcaaa atcaactctg 2761 tataatagca cattctctac tttttaaaga tcagaaatgc tagaattctt gacttttgtg 2761 tataatagca cattctctac tttttaaaga tcagaaatgc tagaattctt gacttttgtg 2821 tatgggtagt aaatctagct cactgaaaat cagagtgaaa cgcctttaca tttgtgcgga 2821 tatgggtagt aaatctagct cactgaaaat cagagtgaaa cgcctttaca tttgtgcgga 2881 tagagaagtt aactctccct catatgtcac tgtgctacca taatccctac attttctgtc 2881 tagagaagtt aactctccct catatgtcac tgtgctacca taatccctac attttctgtc 2941 tgttctagtc taagaatatt gttatagatg gaagttagga ccattagccc acagatgcgt 2941 tgttctagtc taagaatatt gttatagatg gaagttagga ccattagccc acagatgcgt 3001 gtattctctc agacataccg gtgtagatgc catatttctg atgtcttctt aatgtctgtg 3001 gtattctctc agacataccg gtgtagatgc catatttctg atgtcttctt aatgtctgtg 3061 aaagcaactg gcatctacaa taaatcacac ttagaactgg ttagaggact ccctcacttt 3061 aaagcaactg gcatctacaa taaatcacac ttagaactgg ttagaggact ccctcacttt 3121 tgttgtccat gtggttccct tccgtggacc agccgtaata aagagccaag gtagtgatgg 3121 tgttgtccat gtggttccct tccgtggacc agccgtaata aagagccaag gtagtgatgg 3181 tggccacgtg cctcgttgct atttttaaag taatattcag atgtggtttt aaatttagat 3181 tggccacgtg cctcgttgct atttttaaag taatattcag atgtggtttt aaatttagat 3241 tatgtattcc ttttgaaaca taagaaaaac atttaaacct atgctgaaaa tacgataaaa 3241 tatgtattcc ttttgaaaca taagaaaaac atttaaacct atgctgaaaa tacgataaaa 3301 gaaaaacaac tccaatatgc taaaagttaa atatggtatt taagaaaata gtcatgtatg 3301 gaaaaacaac tccaatatgc taaaagttaa atatggtatt taagaaaata gtcatgtatg 3361 caattgagaa agtctataat ttattttaca gaaaagctgg aagattatga ctagatatgg 3361 caattgagaa agtctataat ttattttaca gaaaagctgg aagattatga ctagatatgg 3421 aaatattttt tctgaatttt tttttatatt tcctccgact tacctctttt tgaaaagaga 3421 aaatattttt tctgaatttt tttttatatt tcctccgact tacctctttt tgaaaagaga

3481 gtttttatta aatgaaccat catgatattg gctgaaaagt tctacattct attattgtat 3481 gtttttatta aatgaaccat catgatattg gctgaaaagt tctacattct attattgtat

3541 tgtaacacac atgtattgat gattttcatt aagagtttca gattaacttt gaaaaatatt 3541 tgtaacacac atgtattgat gattttcatt aagagtttca gattaacttt gaaaaatatt 3601 ccacatggta atcttataaa ttctgtttaa ttacatctgt aaatattatg tgtgtgatag 3601 ccacatggta atcttataaa ttctgtttaa ttacatctgt aaatattatg tgtgtgatag 3661 tattcaataa agtaaaatca aattgtcaaa aaaaaaaaaa aaa 3661 tattcaataa agtaaaatca aattgtcaaa aaaaaaaaaa aaa

E2

MSUD Type II

Protein sequence

MAAVRMLRTWSRNAGKLICVRYFQTCGNVHVLKPNYVCFFGYPSFKYSHPHHFLKTTAALRGQVVQFKLSDIGEGIREVTVKEWYVKEGDTVSQFDSICEVQSDKASVTITSRYDGVIKKLYYNLDDIAYVGKPLVDIETEALKDSEEDVVETPAVSHDEHTHQEIKGRKTLATPAVRRLAMENNIKLSEVVGSGKDGRILKEDILNYLEKQTGAILPPSPKVEIMPPPPKPKDMTVPILVSKPPVFTGKDKTEPIKGFQKAMVKTMSAALKIPHFGYCDEIDLTELVKLREELKPIAFARGIKLSFMPFFLKAASLGLLQFPILNASVDENCQNITYKASHNIGIAMDTEQGLIVPNVKNVQICSIFDIATELNRLQKLGSVGQLSTTDLTGGTFTLSNIGSIGGTFAKPVIMPPEVAIGALGSIKAIPRFNQKGEVYKAQI

MNVSWSADHRVIDGATMSRFSNLWKSYLENPAFMLLDLK

mRNA sequence1 atttccgggg taagatggct gcagtccgta tgctgagaac ctggagcagg aatgcgggga 61 agctgatttg tgttcgctat tttcaaacat gtggtaatgt tcatgttttg aagccaaatt 121 atgtgtgttt ctttggttat ccttcattca agtatagtca tccacatcac ttcctgaaaa 181 caactgctgc tctccgtgga caggttgttc agttcaagct ctcagacatt ggagaaggga 241 ttagagaagt aactgttaaa gaatggtatg taaaagaagg agatacagtg tctcagtttg 301 atagcatctg tgaagttcaa agtgataaag cttctgttac catcactagt cgttatgatg 361 gagtcattaa aaaactctat tataatctag acgatattgc ctatgtgggg aagccattag 421 tagacataga aacggaagct ttaaaagatt cagaagaaga tgttgttgaa actcctgcag 481 tgtctcatga tgaacataca caccaagaga taaagggccg aaaaacactg gcaactcctg 541 cagttcgccg tctggcaatg gaaaacaata ttaagctgag tgaagttgtt ggctcaggaa 601 aagatggcag aatacttaaa gaagatatcc tcaactattt ggaaaagcag acaggagcta 661 tattgcctcc ttcacccaaa gttgaaatta tgccacctcc accaaagcca aaagacatga 721 ctgttcctat actagtatca aaacctccgg tattcacagg caaagacaaa acagaaccca 781 taaaaggctt tcaaaaagca atggtcaaga ctatgtctgc agccctgaag atacctcatt 841 ttggttattg tgatgagatt gaccttactg aactggttaa gctccgagaa gaattaaaac 901 ccattgcatt tgctcgtgga attaaactct cctttatgcc tttcttctta aaggctgctt 961 ccttgggatt actacagttt cctatcctta acgcttctgt ggatgaaaac tgccagaata 1021 taacatataa ggcttctcat aacattggga tagcaatgga tactgagcag ggtttgattg 1081 tccctaatgt gaaaaatgtt cagatctgct ctatatttga catcgccact gaactgaacc 1141 gcctccagaa attgggctct gtgggtcagc tcagcaccac tgatcttaca ggaggaacat 1201 ttactctttc caacattgga tcaattggtg gtacctttgc caaaccagtg ataatgccac 1261 ctgaagtagc cattggggcc cttggatcaa ttaaggccat tccccgattt aaccagaaag 1321 gagaagtata taaggcacag ataatgaatg tgagctggtc agctgatcac agagttattg 1381 atggtgctac aatgtcacgc ttctccaatt tgtggaaatc ctatttagaa aacccagctt 1441 ttatgctact agatctgaaa tgaagactga taagacattc ttgaactttt tgagcttcca 1501 aagagtatgt aaaccctagc tgtgccagca catgttcatc tttacaattt atattgtaaa 1561 cgatttgtat cgtatgatta aggatctaag gcacaatatt tgtcactgtt ctattagact 1621 ttttactgaa aatgaataat ggtgtaatgg ttctcctggg gctgtcacat tttataggtc 1681 agagtgtgac ttcttaatat ggtgctgatg tttttgtgtc aatggcttga aactggcaag 1741 attaacaaaa ttaggccggg catggtggct cacgcctgta atccagcact ttgggaggcc 1801 caggtggggc gatcacctga ggttagaagt ttgagaccag cctggccaac atggtgaaac 1861 ctggcctcta cctaaaaaat acaaaattga ccgggtgtgg tggtgggtac cgctacttgg 1921 gaggctgagg caggagaatc gcttgaacct gggaggtgga ggttgcagtg agctgagatc 1981 gtgctattgc actccagcct gggcgacaga gcaagacgcc atctcaaaaa caaaaaaaac2041 aaaattcatg ttactaaaag acaggtagcc atatacagac agtatatgcc ctattttttt2101 taactgactc ttaatgaaac tttaatttta cttaattaag aaatggaatt tatatacaaa2161 aatattttcc atttccgtta ttatgctaat tgttgtatga aataagtgca attatacttc2221 tcttttgaga tatccaagag tatattcttg ctctgtatag agaatatcat ctgatagtgt2281 cttatttata ttaattaatg tctttgaaaa gggaaaagta taaactggcc ttaaaattgt

2341 ccaattatag ttttataacc agtctattaa aggtgtttgt ttaaaatgga tatagtttta 2401 gatttgtggt aatgctttgg tattttcttg gggaagacct tcacctttgc aaacttccct 2461 catgtaagga aggtacttta aatgtagcag ccactgacat ttcttttttt aaaaaaaatt 2521 tgagaagtct acttcctttt aacttttttg gtcttcagct aaaaaatagg ataagaaatt 2581 aaggtctatt ccattctcca tatcctgggt aagaatgtaa ataagaggag aaggaagagt 2641 ctaatagtaa ttatggatat aaaaaataag aaattttgta tagaaatgaa ggtttcataa 2701 tgatcatttt gttaaaggtc tactttaatc agaaatagca acgagatgaa tgtatccaac 2761 atttcaattt gcattcggaa atccatgttg tttctaatat tgtccagttg aaaactgtat 2821 gccaaaatta gttgtttaag tgaagttttg tgacagaaaa aaggttgttt taatatctac 2881 ttggtttttc tcaaaatgga aataatttta aaatcaggaa agaataaatc agccaggtgt 2941 gatgacttgt aactgtaatc ccagttatag gggaggctga agcaggagga tcacttgagg 3001 ccaggagttt gagaccagcc tgggcaacat agtgagatcc catctcaaaa aacattattt 3061 ttaaaattag cctggtggct cacgcctgta atcccagcac tttgggaggc cgaggtggcc 3121 agatcacctg aggtcaggag ttcgagacca ccctggccaa catggtgaaa ccccatctct 3181 acagttttgt aaaaatacaa aaattacctg ggcctggtgc acaggcctgt agtcccagct 3241 acttgggagg ctgaggcagg agaattgctt gagcccaaga ggtggaggtt acagtgagca 3301 gagatcacac cactgcactc cagcctgggt ggcagagcaa cacttcgtct cagaaaaaaa 3361 aaaaaaaacc aaaaaccaaa aagccaagtg tggtggtgtg cacctatagt cccagctact 3421 caggaagctg agacaagagg atcaattgag cccaggagtt caaagctgta gtgagctgtc 3481 attgtgccac tatcctccag tatgggtgac agagtgagac ctggtctcta aaaat

MSUD Type II - MutationsMSUD Type II - Mutations

Exon(e)/Intron(i) Exon(e)/Intron(i) Codon Codon MutationMutation ConsequenceConsequence

7 (e)7 (e) 215215 TTTTT T → T→ TGGTT Phe Phe → Cys→ Cys

4 (i)4 (i) -- -- 17-bp insertion, 17-bp insertion, frameshiftframeshift

8 (e)8 (e) -- AAGGgt gt → A→ AAAgtgt Exon 8 deletionExon 8 deletion

-- -- 15 to 20-bp deletion15 to 20-bp deletion --

8 (i)8 (i) -- AGAGggt t → AGt→ AGt Exon 8 deletionExon 8 deletion

2 (e)2 (e) -- -- Exon 2 deletionExon 2 deletion

2 (e)2 (e) -- CCATATG G → CG→ CG FrameshiftFrameshift

6 (e)6 (e) 163163 GGAA AA → → TTAAAA Glu Glu → Ter→ Ter

4 (e)4 (e) 7777 CCAT AT → → TTATAT Ile Ile → Thr→ Thr

5 (i)5 (i) -- ATATgtgta a → Ata→ Ata Exon 5 deletionExon 5 deletion

MSUD Type IIIMSUD Type III

ExonExon CodonCodon MutationMutation ConsequenceConsequence

N/AN/A 3737 AAAA AA → → GGAAAA Lys Lys → Glu→ Glu

N/AN/A 453453 CCCCG G → C→ CTTGG Pro Pro → Leu→ Leu

E3

Protein SequenceMQSWSRVYCS LAKRGHFNRI SHGLQGLSAV PLRTYADQPI DADVTVIGSG PGGYVAAIKAAQLGFKTVCI EKNETLGGTC LNVGCIPSKALLNNSHYYHM AHGTDFASRG IEMSEVRLNLDKMMEQKSTA VKALTGGIAH LFKQNKVVHV NGYGKITGKN QVTATKADGG TQVIDTKNILIATGSEVTPF PGITIDEDTI VSSTGALSLKKVPEKMVVIG AGVIGVELGS VWQRLGADVTAVEFLGHVGG VGIDMEISKN FQRILQKQGF KFKLNTKVTG ATKKSDGKID VSIEAASGGKAEVITCDVLL VCIGRRPFTK NLGLEELGIE LDPRGRIPVN TRFQTKIPNI YAIGDVVAGPMLAHKAEDEG IICVEGMAGG AVHIDYNCVP SVIYTHPEVA WVGKSEEQLK EEGIEYKVGKFPFAANSRAK TNADTDGMVK ILGQKSTDRV LGAHILGPGA GEMVNEAALA LEYGASCEDIARVCHAHPTL SEAFREANLA ASFGKSINF

mRNA sequence 1 gcgcagggag gggagacctt ggcggacggc ggagccccag cggaggtgaa agtattggcg 61 gaaaggaaaa tacagcggaa aaatgcagag ctggagtcgt gtgtactgct ccttggccaa 121 gagaggccat ttcaatcgaa tatctcatgg cctacaggga ctttctgcag tgcctctgag 181 aacttacgca gatcagccga ttgatgctga tgtaacagtt ataggttctg gtcctggagg 241 atatgttgct gctattaaag ctgcccagtt aggcttcaag acagtctgca ttgagaaaaa 301 tgaaacactt ggtggaacat gcttgaatgt tggttgtatt ccttctaagg ctttattgaa 361 caactctcat tattaccata tggcccatgg aacagatttt gcatctagag gaattgaaat 421 gtccgaagtt cgcttgaatt tagacaagat gatggagcag aagagtactg cagtaaaagc 481 tttaacaggt ggaattgccc acttattcaa acagaataag gttgttcatg tcaatggata 541 tggaaagata actggcaaaa atcaagtcac tgctacgaaa gctgatggcg gcactcaggt 601 tattgataca aagaacattc ttatagccac gggttcagaa gttactcctt ttcctggaat 661 cacgatagat gaagatacaa tagtgtcatc tacaggtgct ttatctttaa aaaaagttcc 721 agaaaagatg gttgttattg gtgcaggagt aataggtgta gaattgggtt cagtttggca 781 aagacttggt gcagatgtga cagcagttga atttttaggt catgtaggtg gagttggaat 841 tgatatggag atatctaaaa actttcaacg catccttcaa aaacaggggt ttaaatttaa 901 attgaataca aaggttactg gtgctaccaa gaagtcagat ggaaaaattg atgtttctat 961 tgaagctgct tctggtggta aagctgaagt tatcacttgt gatgtactct tggtttgcat 1021 tggccgacga ccctttacta agaatttggg actagaagag ctgggaattg aactagatcc 1081 tagaggtaga attccagtca ataccagatt tcaaactaaa attccaaata tctatgccat 1141 tggtgatgta gttgctggtc caatgctggc tcacaaagca gaggatgaag gcattatctg 1201 tgttgaagga atggctggtg gtgctgtgca cattgactac aattgtgtgc catcagtgat 1261 ttacacacac cctgaagttg cttgggttgg caaatcagaa gagcagttga aagaagaggg 1321 tattgagtac aaagttggga aattcccatt tgctgctaac agcagagcta agacaaatgc 1381 tgacacagat ggcatggtga agatccttgg gcagaaatcg acagacagag tactgggagc 1441 acatattctt ggaccaggtg ctggagaaat ggtaaatgaa gctgctcttg ctttggaata 1501 tggagcatcc tgtgaagata tagctagagt ctgtcatgca catccgacct tatcagaagc 1561 ttttagagaa gcaaatcttg ctgcgtcatt tggcaaatca atcaactttt gaattagaag 1621 attatatatt tttttttctg aaatttcctg ggagcttttg tagaagtcac attcctgaac 1681 aggatattct cacagctcca agaatttcta ggactgaatt atgaaacttt tggaaggtat 1741 ttaataggtt tggacaaaat ggaatactct tatatctata ttttacataa atttagtatt 1801 ttgtttcagt gcactaatat gtaagacaaa aaggactact tattgtagtc atcctggaat 1861 atctccgtca actcatattt tcatgctgtt catgaaagat tcaatgcccc tgaatttaaa 1921 tagctctttt ctctgataca gaaaagttga attttacatg gctggagcta gaatttgata 1981 tgtgaacagt tgtgtttgaa gcacagtgat caagttattt ttaatttggt tttcacattg 2041 gaaacaagtc agtcattcag atatgattca aatgtctata aaccaaactg atgtaagtaa 2101 atggtctctc acttgtttta tttaacctct aaattctttc attttagggg tagcatttgt 2161 gttgaagagg ttttaaagct tccattgttg tctgcaactc tgaagggtaa ttatatagtt 2221 acccaaatta agagagtcta tttacggaac tcaaatacgt gggcattcaa atgtattaca 2281 gtggggaatg aagatactga aataaacgtc ttaaatattc

Metabolic functionsMetabolic functions

Branched chain dehydrogenase complex Branched chain dehydrogenase complex (BCKAD)(BCKAD)

3 catalytic components: branched-chain 3 catalytic components: branched-chain alpha-keto acid decarboxylase (E1), alpha-keto acid decarboxylase (E1), lipoamide acyltransferase (E2) and lipoamide acyltransferase (E2) and lipoamide dehydrogenase (E3) lipoamide dehydrogenase (E3)

2 regulatory enzymes: kinase and 2 regulatory enzymes: kinase and phosphotasephosphotase

Encoded by 6 genetic lociEncoded by 6 genetic loci Mutation in any of the loci can result in Mutation in any of the loci can result in

defectdefect Defect in BCKAD causes a block in BCKA Defect in BCKAD causes a block in BCKA

oxidative decarboxylationoxidative decarboxylation Accumulation of BCKAAccumulation of BCKA

(1) transamination by BCAA amino transferase(2) oxidative decarboxylation by BCKAD(3) dehydrogenation by isovaleryl-CoA dehydrogenase (4) dehydrogenation by alpha-methyl branched chain cyl-CoA dehydrogenase

(Chuang & Shih, 1995)

Screening and DiagnosisScreening and Diagnosis Prenatal diagnosisPrenatal diagnosis

analysis of cultured amniocytes obtained at mid-trimester analysis of cultured amniocytes obtained at mid-trimester amniocentesisamniocentesis

direct analysis of tissues or cultured cells from chorionic villi sample direct analysis of tissues or cultured cells from chorionic villi sample taken during first trimestertaken during first trimester

Use allele-specific oligonucleotide (ASO) probe following PCR to detect Use allele-specific oligonucleotide (ASO) probe following PCR to detect mutation in DNA obtained from amniocytes mutation in DNA obtained from amniocytes

Attempts at measuring amniotic fluid concentration of BCAA, BCKA Attempts at measuring amniotic fluid concentration of BCAA, BCKA and and αα-hydroxyacids have been unsuccessful-hydroxyacids have been unsuccessful

Routine newborn screeningRoutine newborn screening Guthrie bacterial inhibition assay Guthrie bacterial inhibition assay

Increase leucine levels in blood spotsIncrease leucine levels in blood spotsDetect classic, intermediate and E3-deficient MSUD but intermediateDetect classic, intermediate and E3-deficient MSUD but intermediatemay be missed due to lower leucine levels than classicmay be missed due to lower leucine levels than classic

Tandem mass spectroscopy coupled with fast atom bombardment Tandem mass spectroscopy coupled with fast atom bombardment (FAB) ionisation (FAB) ionisation

Detect organic acids and amino acids abnormalities in blood and Detect organic acids and amino acids abnormalities in blood and urineurine

samples on filter papersamples on filter paper

Screening and Diagnosis cont.Screening and Diagnosis cont. General diagnosis or genetic studiesGeneral diagnosis or genetic studies

Urine 2,4-dinitrophenylhydrazine (DNPH) testUrine 2,4-dinitrophenylhydrazine (DNPH) test Gas chromatographic mass spectroscopy (GC-MS)Gas chromatographic mass spectroscopy (GC-MS) Enzymic studies of cell cultures (skin fibroblasts and lymphoblasts)Enzymic studies of cell cultures (skin fibroblasts and lymphoblasts) Allele-specific oligonucleotide (ASO) probingAllele-specific oligonucleotide (ASO) probing

Historical perspectiveHistorical perspective

Diagnosis relied on the recognition of clinical symptoms and signs and Diagnosis relied on the recognition of clinical symptoms and signs and Chemical and enzymological analysis were performed if indicated Chemical and enzymological analysis were performed if indicated (Galjaard 1980)(Galjaard 1980)

Therapies and Management Therapies and Management Long term dietary managementLong term dietary management Restrict intake of BCAA in diet to Restrict intake of BCAA in diet to

the amount essential for growththe amount essential for growth Start as soon as possible and Start as soon as possible and

continue for lifecontinue for life Treat classic and intermediate Treat classic and intermediate

MSUD patients the same wayMSUD patients the same way For intermittent MSUD, decrease For intermittent MSUD, decrease

protein intake during episodesprotein intake during episodes Monitor plasma BCAA levels Monitor plasma BCAA levels

weekly for the first 6 months and weekly for the first 6 months and keep as close to normal as keep as close to normal as possiblepossible

A trial of thiamine therapy is A trial of thiamine therapy is recommended to determine recommended to determine thiamine responsiveness in all thiamine responsiveness in all new patientsnew patients

History of dietary therapiesHistory of dietary therapiesDietary therapies started in 1959.Dietary therapies started in 1959.Gelatin has low BCAA and was Gelatin has low BCAA and was used as a source of BCAA in used as a source of BCAA in England in the early days. A England in the early days. A synthetic formula was developed by synthetic formula was developed by Snyderman et al in the United Snyderman et al in the United States which consisted of 18 amino States which consisted of 18 amino acids (based on breastmilk acids (based on breastmilk composition) carbohydrates, fat, composition) carbohydrates, fat, minerals and vitamins. Based on minerals and vitamins. Based on this formula, other commercial this formula, other commercial medical diets have since been medical diets have since been created. created.

Therapies and Management cont.Therapies and Management cont.Acute-phase managementAcute-phase management Infection and stress can cause a significant accumulation of BCAA and BCKA which can Infection and stress can cause a significant accumulation of BCAA and BCKA which can

be life threateningbe life threatening Treatment involves:Treatment involves:

Rapid removal of toxic metabolitesRapid removal of toxic metabolitesExchange transfusionExchange transfusion (early 1960’s) achieved limited success (early 1960’s) achieved limited successPeritoneal dialysisPeritoneal dialysis (1969) produced significant improvement within hours. (1969) produced significant improvement within hours.

It is simple to implement and has become an established procedure forIt is simple to implement and has become an established procedure for treating patients in crisis treating patients in crisis

HemodialysisHemodialysis is equally successful but requires specialised equipment is equally successful but requires specialised equipment and personneland personnel

CContinuous arteriovenous hemoperfusion ontinuous arteriovenous hemoperfusion can be used for adults butcan be used for adults but hashas technical limitations when applied to newbornstechnical limitations when applied to newborns Parenteral Nutritional therapyParenteral Nutritional therapy

BCAA-freeBCAA-free L-amino acid mixture combined with glucose, lipid, electrolytes L-amino acid mixture combined with glucose, lipid, electrolytes and vitaminsand vitamins Minimise catabolic state and/or promote anabolismMinimise catabolic state and/or promote anabolism

use use insulin and carbohydrateinsulin and carbohydrate to promote anabolism to promote anabolism

Key ReferencesKey References Bondy, P.K. & Rosenberg, L.C. 1980, Bondy, P.K. & Rosenberg, L.C. 1980, Metabolic Control and Disease, Metabolic Control and Disease, 8th 8th

Edition, W.B. Saunders Company, PhiladelphiaEdition, W.B. Saunders Company, Philadelphia Galjaard, H. 1980, Galjaard, H. 1980, Genetic Metabolic Diseases: Early Diagnosis and Prenatal Genetic Metabolic Diseases: Early Diagnosis and Prenatal

Analysis, Analysis, Elsevier/North-Holland Biomedical Press, AmsterdamElsevier/North-Holland Biomedical Press, Amsterdam Chuang, D.T. & Shih, V.E. 1995, ‘Disorders of Branched Chain Amino Acid Chuang, D.T. & Shih, V.E. 1995, ‘Disorders of Branched Chain Amino Acid

and Keto Acid Metabolism’, in and Keto Acid Metabolism’, in The Metabolic and Molecular Bases of The Metabolic and Molecular Bases of Inherited Diseases, Inherited Diseases, vol. 1,vol. 1, 77thth Edition, eds Scriver et al., McGraw-Hill, New Edition, eds Scriver et al., McGraw-Hill, New YorkYork

OMIM, URL: http://www3.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=248600OMIM, URL: http://www3.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=248600 Ensemble, URL: http://www.ensembl.org/homo_sapians/genereview?Ensemble, URL: http://www.ensembl.org/homo_sapians/genereview?

gene=ENSG00000137992 (ENSG00000142046, ENSG00000083123, gene=ENSG00000137992 (ENSG00000142046, ENSG00000083123, ENSG00000091140)ENSG00000091140)

Other therapiesOther therapies Introducing subunits of BCKDH enzyme into cells using a retrovirousIntroducing subunits of BCKDH enzyme into cells using a retrovirous Liver transplantLiver transplant Somatic gene therapySomatic gene therapy

Therapies and Management cont.Therapies and Management cont.