Handbook of Clinical Neurology, Vol. 113 (3rd series)Pediatric Neurology Part IIIO. Dulac, M. Lassonde, and H.B. Sarnat, Editors© 2013 Elsevier B.V. All rights reserved

Chapter 169

Disorders of pyruvate metabolism

LINDA DE MEIRLEIR*

Pediatric Neurology and Metabolism, Universitair Ziekenhuis Brussel, Brussels, Belgium

INTRODUCTION

Pyruvate dehydrogenase (PDH) deficiency and pyruvatecarboxylase (PC) deficiency are the most common disor-ders in pyruvate metabolism and will be discussed in thischapter.

Owing to the role of pyruvate in energy metabolism,gluconeogenesis, lipogenesis, and amino acid synthesis,defects in pyruvate metabolism almost invariably affectthe central nervous system. The severity and the clinicalphenotypes vary, ranging from overwhelming neonatallactic acidosis and early death to milder presentationsat a later age. Diagnosis depends on biochemical ana-lyses in plasma, urine, and cerebrospinal fluid (CSF) fol-lowed by definitive enzymatic assays and DNA analysis.

PYRUVATEDEHYDROGENASE COMPLEX

The pyruvate dehydrogenase complex (PDHc) has threemain components. E1, a heterotetramer a2b2, decarbox-ylates pyruvate and transfers the acetyl group to dihydro-lipoamide acetyl transferase E2. E2 is a transacetylasethat utilizes covalently bound lipoic acid. The lipoic acidis reoxidized by E3. In addition there are other subunits,E3 binding protein and two complex-regulating enzymes:PDH kinase, which inactivates the complex, and PDHphosphatase, which reactivates the complex (Robinsonet al., 1980).

In the absence ofmitochondrial oxidation, pyruvate isreduced to lactate. In the presence of oxygen and normalmitochondrial function, pyruvate can be oxidized toacetyl-CoA via PDHc.

Clinical presentations

PDHc deficiency is most often due to mutations in thefirst component of the enzyme complex, pyruvatedehydrogenase E1a (responsible for 70% of the PDH

*Correspondence to: Linda De Meirleir, MD, PhD, Pediatric Neu

Brussels, Belgium. Tel: þ32-2-477-5784, Fax: þ32-2-477-5786, E-m

deficiencies). The gene encoding this subunit is locatedon the X chromosome (Brown et al., 1989).

E1a DEFICIENCY

There is a spectrum of clinical presentations in E1a defi-ciency. The onset can be in the neonatal period, ininfancy, or later and appears differently in boys andgirls. Female patients tend to have a more homogeneousclinical presentation, but with variable severity (Kerret al., 1996; Robinson et al., 1996; De Meirleir et al.,1998; De Meirleir, 2002).

In males there are three different major presenta-tions. The first is a severe neonatal lactic acidosis whichcan be associated with brain dysgenesis (such as corpuscallosum agenesis).

The second is later in infancy and childhood, present-ing as a Leigh’s encephalopathy and intermittent ataxia.In boys with Leigh’s encephalopathy, the initial presenta-tion within the first 5 years of life includes respiratorydisturbances/apnea or episodic weakness and ataxia withabsent tendon reflexes due to a peripheral neuropathy.A moderate to severe developmental delay becomes evi-dent in the following years. Intermittent dystonic postur-ing of the lower limbs occurs frequently. The group withLeigh’s encephalopathy is quantitatively the most impor-tant one.

The third presentation in a very small subset of malepatients is initially much less severe, with bouts of epi-sodic ataxia after carbohydrate-rich meals and progres-sing slowly over several years into a mild Leigh’sencephalopathy. A few patients have developed an acuteperipheral neuropathy during infancy (Strassburg et al.,2006) or an acute episodic ataxia (Debray et al., 2008),some without cognitive decline. Some also develop par-oxysmal dystonia or atypical absences (Barnerias et al.,

rology and Metabolism, UZ-Brussel, Laarbeeklaan 101, 1090

ail: linda.demeirleir@uzbrussel.be

EI

2010). There is even a report of a cognitively normalmale patient (Bachman-Gagescu and Merrit, 2009).

Females with PDHE1a deficiency tend to have amoreuniform clinical presentation. This includes dysmorphicfeatures, microcephaly and moderate to severe mentalretardation and spastic di- or quadriplegia, simulatingnonprogressive cerebral palsy. The dysmorphism con-sists of narrowed head with frontal bossing, a wide nasalbridge, an upturned nose, a long philtrum and flared nos-trils. Some of these features can also be seen in fetalalcohol syndrome (De Meirleir et al., 1993). Other fea-tures are low-set ears, short fingers, and short proximallimbs and simian creases. Almost all female patientshave seizures. The seizures usually appear within thefirst 6months of life and are often diagnosed as infantilespasms (flexor and extensor) or severe myoclonic

1668 L. DE M

Fig. 169.1. A 26-year-old male patient with PDHE1a, with L

Dr. E. Scalais, Luxembourg). The MRI shows typical hyperinten

seizures. Severe neonatal lactic acidosis can be present,but can also be absent.

The different clinical presentation betweenmales andfemales was recently confirmed in 20 patients withmutations in PDHE1a (Quintana et al., 2009a) and in apaper by Barnerias et al. (2010).

Neuroradiological abnormalities such as corpuscallosum agenesis and dilated ventricles with severecortical/subcortical atrophy are typically seen in females(Fig. 169.1). In boys with PDHE1a deficiency basal gang-lia and midbrain abnormalities (Fig. 169.2) are oftenfound.

Neuropathology can reveal various degrees of dys-genesis of the corpus callosum (Michotte et al., 1993).This can be associated with other migrational defectssuch as the absence of the medullary pyramids, ectopic

RLEIR

eigh’s encephalopathy and R263G mutation (courtesy of

se signal in the putamen, dentate nuclei and tegmentum.

Fig. 169.2. MRI in several female caseswith PDHE1a (courtesy ofDr. EMorava, Nijmegen). Typical enlarged ventricles, cortical

atrophy, and corpus callosum agenesis.

DISORDERS OF PYRUVATE METABOLISM 1669

olivary nuclei, abnormal Purkinje cells in the cerebellum,dysplasia of the dentate nuclei, subcortical heterotopiasand pachygyria.

Other pyruvate dehydrogenase complexdeficiencies

PDHE1b DEFICIENCY

Only a few cases with PDHE1b deficiency have beendescribed (Brown et al., 2004). These patients presentwith early onset lactic acidosis and severe developmentaldelay. Two patients with a Leigh syndrome were alsodescribed (Quintana et al., 2009b).

PDH PHOSPHATASE DEFICIENCY

Maj et al. (2005) described two brothers with hypotoniaand feeding difficulties and delayed psychomotor devel-opment, stable on a ketogenic diet, and a mutation in thePDH phosphatase gene. Another case had a severe neo-natal lactic acidosis (Cameron et al., 2009).

E2 DEFICIENCY

A few cases of deficiency of the second component ofPDH complex (dihydrolipoamide transacetylase, E2)have also been described (Robinson et al., 1990). Headet al. (2005) published E2 deficient patients with a clin-ical picture of severe dystonia and lesions in the globuspallidus and resembling pantothenate kinase degenera-tion. Episodic dystonia was also found in two sisters withE2 deficiency and a good response on a ketogenic diet(McWilliam et al., 2010).

E3 DEFICIENCY

Dihydrolipoamide dehydrogenase (E3) deficiency pre-sents with severe and progressive hypotonia and failureto thrive, starting within the first months of life. Progres-sively, hypotonia, psychomotor retardation, microceph-aly, and spasticity occur. Some patients develop a typicalpicture of Leigh encephalopathy (Elpeleg et al., 1995,1997; Grafakou et al., 2003; Hong et al., 2003). A clinicalReye-like picture with liver involvement and myopathywith myoglobinuria without mental retardation has

EI

been seen in Ashkenazi Jewish patients with an E3 defi-ciency (Shaag et al., 1999).

E3BP DEFICIENCY

These patients have hypotonia, delayed psychomotordevelopment and often prolonged survival (Aral et al.,1997; Brown et al., 2002). Others have early onset neona-tal lactic acidosis, associated with subependymal cystsand thin corpus callosum. The clinical spectrum ofE3BP deficiency might become broader as more patientsare diagnosed.

Diagnosis

Themost important laboratory test for the diagnosis of apossible PDHc deficiency is the measurement of plasmaand CSF lactate and pyruvate. Analysis of plasma aminoacids and urinary organic acidsmay also be useful.Whilethe L/P ratio is characteristically normal, it can be ele-vated if the patient is acutely ill. In contrast to deficien-cies of PC, fasting hypoglycemia is not an expectedfeature of PDHc deficiency, and blood lactate and pyru-vate usually decrease after fasting. CSF for measure-ment of lactate and pyruvate is certainly indicated asthe elevation might only be in the CSF with normal lac-tate and pyruvate concentration in plasma.

The most commonly used materials for assay ofPDHc are cultured skin fibroblasts, fresh blood lympho-cytes, or skeletal muscle (Sheu et al., 1981). A molecularanalysis of the PDHE1a gene in girls is often more rapidthan measuring the enzyme activity as the latter can pro-duce false negative results, depending on which tissue isstudied.

PDHcmust also be measured in an activated (dephos-phorylated) state, which can be done by preincubation ofwhole cells or mitochondria with dichloroacetate (DCA,an inhibitor of the kinase). In E1-phosphatase deficiencythere is a deficiency in native PDH activity, but on acti-vation of the PDH complex with DCA, activity becomesnormal. The three catalytic components of PDHc can beassayed separately. Immunoblotting of the componentsof PDHc can help distinguish if a particular protein ismissing. E3BP, which anchors E3 to the E2 core of thecomplex, can only be evaluated using immunoblotting,since it has no catalytic activity.

Genetics

All of the components of the PDH complex are encodedby nuclear genes. The genes that encode the various sub-units are autosomal except for the E1a subunit gene,which is on the X-chromosome. More than 100 differentmutations of the E1a subunit of the PDH complex havebeen reported (Lissens et al., 2000; Naito et al., 2002a).

1670 L. DE M

Defects in the other subunits, E1b, E2, PDH phosphatasehave been identified in rare cases only.

Treatment and prognosis

The possible treatments for PDHc deficiency are limited.Occasional improvement under a ketogenic diet has beenpublished and this should be tried in each patient (Falket al., 1976; Weber et al., 2001).

Naito et al. (2002b) showed that, after assaying thecells in the presence of different (low and high) concen-trations of thiamine pyrophosphate (TPP), theremight bethiamine responsiveness. Thiamine has been adminis-tered in variable doses (500–2000 mg/day) to patientswith PDHc deficiency, with lowering of blood lactateand an apparent clinical improvement.

DCA offers another potential treatment for PDHcdeficiency. DCA inhibits E1 kinase, thereby keepingany residual E1 activity in its active (dephosphorylated)form. A trial of DCA in children with congenital lacticacidosis, however, failed to improve the clinical diseaseprogression and this compound is therefore not recom-mended at this time (Stacpoole et al., 2008).

PYRUVATE CARBOXYLASEDEFICIENCY

Pyruvate carboxylase (PC) is a biotinylated mitochondrialmatrix enzyme that converts pyruvate and CO2 to oxalo-acetate and has a critical anaplerotic function replenishingtheKrebs cycle intermediates. In addition, PC controls thefirst step of hepatic gluconeogenesis, and is involved inlipogenesis (Attwood, 1995). The enzyme is expressedin several tissues, with highest activity in liver, kidney,adipose tissue, mammary gland, and pancreatic islets,moderate activity in brain, heart, and adrenal gland,and low activity in white blood cells and skin fibroblasts(Jitrapakdee et al., 1996).

Clinical presentations

Pyruvate carboxylase deficiency generates three distinctclinical phenotypes. The infantile form (type A, NorthAmerican form) is characterized by infantile-onset mildto moderate lactic acidemia, severe developmental retar-dation, failure to thrive, hypotonia, pyramidal tract signs,ataxia, convulsions, and ultimately, demise in infancy orearly childhood (Robinson et al., 1984).Metabolic or infec-tious stresses cause vomiting, dehydration, and metabolicacidosis.

Patients with the French clinical phenotype (type B)present with neonatal onset hypothermia, hypotonia,lethargy, convulsions, vomiting, and hepatomegaly.Bizarre ocular eye movements and especially rigidityand hypokinesia (hypokinetic-rigid syndrome) areimportant hallmarks and may orientate to PC deficiency

RLEIR

UV

when associated with severe lactic acidosis (Saudubrayet al., 1976; Garcı́a-Cazorla et al., 2006). Death usuallyoccurs in the first months of life. In these patients, deple-tion of intracellular aspartate and oxaloacetate compro-mises both the catalytic and anaplerotic PC functions.

A third, more benign but rare clinical presentation hasbeen reported. Patients have acute episodes of lactic aci-dosis and ketoacidosis, which respond to hydration andbicarbonate therapy. These patients have a surprisinglynear normal cognitive and neuromotor developmentdespite the severe biochemical enzymatic deficiencyphenotype (Van Coster et al., 1991; Hamilton et al.,1997; Arnold et al., 2001).

DISORDERS OF PYR

Diagnosis

The three forms of PC deficiency have biochemicalabnormalities that partially overlap, but also have spe-cific distinctions that allow differential diagnosis.

In patients with the North American phenotypelactate is increased, while the lactate/pyruvate ratiosare normal or only modestly increased. Ammoniumand citrulline concentrations are normal, while alanineis increased. The 3-OH-butyrate/acetoacetate ratio isnormal or decreased. In the cerebrospinal fluid, lactate,lactate/pyruvate ratio and alanine concentrations areincreased and glutamine is decreased. The urinaryorganic acid profile is characterized by large amountsof lactate, pyruvate, 3-OH-butyrate and a-ketoglutarate.

Patients with the French phenotype have metabolicacidosis, hyperlactacidemia and sometimes fastinghypoglycemia. Blood lactate and pyruvate concentra-tions are elevated and with increased lactate/pyruvateratio. The 3-OH-butyrate/acetoacetate ratio is decreased.Hyperammonemia is a constant finding, as is an increaseof blood citrulline, lysine, and proline.

A diagnosis of PC deficiency should be considered inany child presenting with lactic acidosis and neurologicalabnormalities associated with hypoglycemia, hyperam-monemia, or ketosis. In neonates, a high lactate/pyruvateratio associated with a low 3-OH-butyrate/acetoacetateratio is pathognomonic. Cultured skin fibroblasts arepreferentially used for assessing the catalytic activityof PC (DeVivo et al., 1977).

Only few detailed neuroradiological descriptions ofPC deficiency are reported in the literature. In the severeforms there can be subdural effusion, severe brainlesions that appear as ischemia-like and periventricularhemorrhagic cysts. Even antenatal ischemic-like brainlesions have been demonstrated (Brun et al., 1999;Garcı́a-Cazorla et al., 2006). Upon progression, cerebralatrophy and delay in myelination can be observed. Thefinding of cystic periventricular leukomalacia in a neo-nate associated with lactic acidosis suggests pyruvate

carboxylase deficiency. Schiff et al. (2006) reported apatient who survived after neonatal lactic acidemiaand was alive at 9 years of age with mild developmentaldelay. Brain MRI at 18 months revealed subcorticalleukodystrophy.

Neuropathology can reveal widespread demyelin-ation of the cerebral and cerebellar white matter andsymmetrical paraventricular cavities around frontaland temporal horns are the most striking abnormalities(Saudubray et al., 1976; Brun et al., 1999).

Genetics

PC deficiency is an autosomal recessive disorder. Morethan half the patients with the French phenotype lackthe PC protein. Patients with the North American pheno-type or the more benign type generally have cross-reacting material (CRM-positive) and possess enoughresidual catalytic activity to sustain the anaplerotic roleof PC. The PC cDNAwas first cloned from a human livercDNA library (Freytag and Collier, 1984). The mRNAtranscript is 4.2 kb and the protein is 125 kDa(MacKay, 1994; Wexler et al., 1994). Several reports onmutations are nowpublished (Carbone et al., 1998, 2002).

Wang et al. (2008) reported the molecular basis foreight cases (one type A, five type B and two type C)of PC deficiency. Mosaicism was found in five cases(one type A, three type B and one type C), and four ofthese cases had prolonged survival. The type B pheno-type correlates with complex missense mutations, dele-tions and splice donor site mutations in the form ofhomozygosity, compound heterozygosity, and mosai-cism. Missense mutations were found in type C patients.Monnot et al. (2009) reported nine novel mutations ofthe PC gene and their study confirmed that type B is con-sistently associated with at least one truncating muta-tion, mostly lying in the C-terminal part, whereas formA always results from the association of two missensemutations in the N-terminal domain.

Treatment

Patients with isolated PC deficiency do not respond tobiotin therapy or to other cofactors. Some patients withpersistent lactic acidosis may require bicarbonate to cor-rect the acidosis. One patient with the French type B(Ahmad et al., 1999) was treated with high doses of cit-rate (7.5 mol/kg/day) and aspartate (10 mmol/kg/day)in order to provide oxaloacetate. Lactate and ketonesdiminished dramatically, and plasma amino acids nor-malized, except for arginine, which required supplemen-tation. In the cerebrospinal fluid, glutamine remainedlow and lysine elevated, showing that the treatmenthad not normalized brain chemistry. Treatment did notimprove neurological outcome.

ATE METABOLISM 1671

EIRLEIR

Mochel et al. (2005) reported a 6-day-old girl withpyruvate carboxylase deficiency type B. Triheptanoin,an odd-carbon triglyceride, was administrated as asource for acetyl-CoA and anaplerotic propionyl-CoA. Although this patient eventually succumbed tosevere infection after 6 months of this treatment,there was an immediate (less than 48 hours) reversalof major hepatic failure with full correction of all bio-chemical abnormalities. Importantly the transport ofC5 ketone bodies, representing alternative energeticfuel for the brain, across the blood–brain barrier, withincreased levels of glutamine and free g-aminobutyricacid (f-GABA) in the cerebrospinal fluid could bedemonstrated.

This treatment should be initiated in other patientswith PC deficiency.

1672 L. DE M

REFERENCES

Ahmad A, Kahler SG, Kishnani PS et al. (1999). Treatment of

pyruvate carboxylase deficiency with high doses of citrate

and aspartate. Am J Med Genet 87: 331–338.

Aral B, Benelli C, Ait-Ghezala G et al. (1997). Mutations in

PDX1, the human lipoyl-containing component X of the

pyruvate dehydrogenase-complex gene on chromosome

11p1, in congenital lactic acidosis. Am J Hum Genet 61:1318–1326.

Arnold GL, Griebel ML, Porterfield M et al. (2001). Pyruvate

carboxylase deficiency. Report of a case and additional evi-

dence for the “mild” phenotype. Clin Pediatr 40: 519–521.Attwood PV (1995). The structure and the mechanism of

action of pyruvate carboxylase. Int J Biochem Cell Biol

27: 231–249.Bachman-Gagescu R, Merrit JL (2009). A cognitively normal

PDH-deficient 18-year-old man carrying the R263G muta-

tion in the PDHA1gene. JIMD Short Report 181 http://dx.doi.org/10.1007/s10545-009-1101-4.

Barnerias C, Saudubray JM, Touati G et al. (2010). Pyruvate

dehydrogenase complex deficiency: four neurological

phenotypes with differing pathogenesis. Dev Med

Child Neurol 52: e1–9.

Brown RM, Dahl HHM, Brown GK (1989). X-chromosome

localization of the functional gene for the E1 alpha subunit

of the human pyruvate dehydrogenase complex. Genomics

4: 174–181.

Brown RM, Head RA, Brown GK (2002). Pyruvate dehydroge-

nase E3 binding protein deficiency. HumGenet 110: 187–191.Brown RM, Head RA, Boubriak II et al. (2004). Mutations in

the gene for the E1b subunit: a novel cause of pyruvate

dehydrogenase deficiency. Hum Genet 115: 123–127.Brun N, Robitaille Y, Grignon A et al. (1999). Pyruvate car-

boxylase deficiency: prenatal onset of ischemia-like brain

lesions in two sibs with the acute neonatal form. Am JMed

Genet 84: 94–101.

Cameron JM, Maj M, Levandovskiy V et al. (2009). Pyruvate

dehydrogenase phosphatase 1 (PDP1) null mutation

produces a lethal infantile phenotype. Hum Genet 125:319–326.

Carbone MA, MacKay N, Ling M et al. (1998). Amerindian

pyruvate carboxylase deficiency is associated with two dis-

tinct missense mutations. Am J Hum Genet 62: 1312–1319.Carbone MA, Applegarth DA, Robinson BH (2002). Intron

retention and frameshift mutations result in severe pyruvate

carboxylase deficiency in two male siblings. Hum Mutat

20: 48–56.Debray FG, Lambert M, Gagne R et al. (2008). Pyruvate dehy-

drogenase deficiency presenting as intermittent isolated

acute ataxia. Neuropediatrics 39: 20–23.DeMeirleir L (2002). Defects of pyruvate metabolism and the

Krebs cycle. J Child Neurol 17: 3S26–S33.

De Meirleir L, Lissens W, Denis R et al. (1993). Pyruvate

dehydrogenase deficiency: clinical and biochemical diag-

nosis. Pediatr Neurol 9: 216–220.

De Meirleir L, Specola N, Seneca S et al. (1998). Pyruvate

dehydrogenase E1alpha deficiency in a family: different

clinical presentation in two siblings. J Inherit Metab Dis

21: 224–226.DeVivoDC,HaymondMW,LeckieMP et al. (1977). The clin-

ical and biochemical implications of pyruvate carboxylase

deficiency. J Clin Endocrinol Metab 45: 1281–1296.Elpeleg ON, RuitenbeekW, Jakobs C et al. (1995). Congenital

lacticacidemia caused by lipoamide dehydrogenase defi-

ciency with favorable outcome. J Pediatr 126: 72–74.

Elpeleg ON, Shaag A, Glustein JZ et al. (1997). Lipoamide

dehydrogenase deficiency in Ashkenazi Jews: an insertion

mutation in the mitochondrial leader sequence. HumMutat

10: 256–257.Falk RE, Cederbaum SD, Blass JP et al. (1976). Ketogenic diet

in the management of pyruvate dehydrogenase deficiency.

Pediatrics 58: 713–721.Freytag SO, Collier KJ (1984). Molecular cloning of a cDNA

for human pyruvate carboxylase. Structural relationship to

other biotin-containing carboxylases and regulation of

mRNA content in differentiating preadipocytes. J Biol

Chem 259: 12831–12837.Garcı́a-Cazorla A, Rabier D, Touati G et al. (2006). Pyruvate

carboxylase deficiency: metabolic characteristics and new

neurological aspects. Ann Neurol 59: 121–127.Grafakou O, Oexle K, van den Heuvel L et al. (2003). Leigh

syndrome due to compound heterozygosity of dihydro-

lipoamide dehydrogenase gene mutations. Description of

the first E3 splice site mutation. Eur J Pediatr 162: 714–718.

Hamilton J, RaeMD, LoganRWet al. (1997). A case of benign

pyruvate carboxylase deficiency with normal develop-

ment. J Inherit Metab Dis 20: 401–403.Head RA, Brown RM, Zolkipli Z et al. (2005). Clinical and

genetic spectrum of pyruvate dehydrogenase deficiency:

dihydrolipoamide acetyltransferase (E2) deficiency. Ann

Neurol 58: 234–241.

Hong YS, Korman SH, Lee J et al. (2003). Identification of a

common mutation (Gly194Cys) in both Arab Moslem and

Ashkenazi Jewish patients with dihydrolipoamide dehy-

drogenase (E3) deficiency: possible beneficial effect of

vitamin therapy. J Inherit Metab Dis 26: 816–818.

DISORDERS OF PYRUVATE METABOLISM 1673

Jitrapakdee S, Walker ME, Wallace JC (1996). Identification

of novel alternatively spliced pyruvate carboxylase

mRNAs with divergent 50-untranslated regions which are

expressed in a tissue-specific manner. Biochem Biophys

Res Commun 223: 695–700.Kerr DS, Wexler ID, Tripatara A et al. (1996). Defects of the

human pyruvate dihydrolipoamide dehydrogenase defi-

ciency. Med Sci Monit 7: 1319–1325.Lissens W, DeMeirleir L, Seneca S et al. (2000). Mutations in

the X-linked pyruvate dehydrogenase (E1) a sububit gene

(PDHA1) in patients with a pyruvate dehydrogenase com-

plex deficiency. Hum Mutat 15: 209–219.MacKay N, Rigat B, Douglas C et al. (1994). cDNA cloning of

human kidney pyruvate carboxylase. Biochem Biophys

Res Commun 202: 1009–1014.McWilliamCA, Ridout CK, BrownRMet al. (2010). Pyruvate

dehydrogenase E2 deficiency: a potentially treatable cause

of episodic dystonia. Eur J of Ped Neurology http://dx.doi.org/10.1016/j.epn.2009.11.001.

Maj MC, MacKay N, Levandovskiy V et al. (2005). Pyruvate

dehydrogenase phosphatase deficiency: identification of

the first mutation in two brothers and restoration of activity

by protein complementation. J Clin Endocrinol Metab 90:

4101–4107.Michotte A, De Meirleir L, Lissens W et al. (1993).

Neuropathological findings of a patient with pyruvate

dehydrogenase E1 alpha deficiency presenting as a cerebral

lactic acidosis. Acta Neuropathol (Berl) 85: 674–678.Mochel F, DeLonlay P, Touati G et al. (2005). Pyruvate car-

boxylase deficiency: clinical and biochemical response to

anaplerotic diet therapy. Mol Genet Metab 84: 305–312.Monnot S, Serre V, Chadefaux-Vekemans B et al. (2009).

Structural insights on pathogenic effects of novelmutations

causing pyruvate carboxylase deficiency. Hum Mutat 30:734–740.

Naito E, Ito M, Yokota I et al. (2002a). Thiamine-responsive

pyruvate dehydrogenase deficiency in two patients caused

by a point mutation (F2005L and L216F) within the thia-

mine pyrophosphate binding site. Biochim Biophys Acta

1588: 79–84.

Naito E, Ito M, Yokota I et al. (2002b). Diagnosis and molec-

ular analysis of three male patients with thiamine-

responsive pyruvate dehydrogenase complex deficiency.

J Neurol Sci 201: 33–37.Quintana E, Gort L, Busquets C et al. (2009a). Mutational

study in the PDHA1 gene of 40 patients supected of pyru-

vate dehydrogenase comlex deficiency. Clin Genet http://dx.doi.org/10.1111/j.1399-004.2009.01313x.

Quintana E, Mayr JA, Garcia Silva MT et al. (2009b). PDH

E1b deficiency with novel mutations in two patients with

Leigh syndrome. JIMD case report 003 http://dx.doi.org/10.1007/s10545-009-1343-1.

Robinson BH, Taylor J, Sherwood WG (1980). The genetic

heterogeneity of lactic acidosis: occurrence of recognizable

inborn errors of metabolism in a pediatric population with

lactic acidosis. Pediatr Res 14: 956–962.

Robinson BH, Oei J, Sherwood WG et al. (1984). The molec-

ular basis for the two different clinical presentations of

classical pyruvate carboxylase deficiency. Am J Hum

Genet 36: 283–294.Robinson BH, MacKay N, Petrova-Benedict R et al. (1990).

Defects in the E2 lipoyl transacetylase and the X-lipoyl

containing component of the pyruvate dehydrogenase com-

plex in patients with lactic acidemia. J Clin Invest 85:1821–1824.

Robinson BH, MacKay N, Chun K et al. (1996). Disorders of

pyruvate carboxylase and the pyruvate dehydrogenase

complex. J Inherit Metab Dis 19: 452–462.Saudubray JM, Marsac C, Charpentier C et al. (1976).

Neonatal congenital lactic acidosiswith pyruvate carboxyl-

ase deficiency in two siblings. Acta Paediatr Scand 65:717–724.

Schiff M, Levrat V, Acquaviva C et al. (2006). A case of

pyruvate carboxylase deficiency with atypical clinical

and neuroradiological presentation. Mol Genet Metab 87:

175–177.Shaag A, Saada A, Berger I et al. (1999). Molecular basis of

lipoamide dehydrogenase deficiency in Ashkenazi Jews.

Am J Med Genet 82: 177–182.

Sheu KFR, Hu CWC, Utter MF (1981). Pyruvate dehydroge-

nase complex activity in normal and deficient fibroblasts.

J Clin Invest 67: 1463–1471.

Stacpoole PW, Gilbert LR, Neiberger RE et al. (2008).

Evaluation of long-term treatment of children with congen-

ital lactic acidosis with dichloroacetate. Pediatrics 121:

e1223–e1228.Strassburg HM, Koch J, Mayr J et al. (2006). Acute flaccid

paralysis as initial symptom in 4 patients with novel

E1alpha mutations of the pyruvate dehydrogenase com-

plex. Neuropediatrics 37: 137–141.Van Coster RN, Fernhoff PM, De Vivo DC (1991). Pyruvate

carboxylase deficiency: a benign variant with normal

development. Pediatr Res 30: 1–4.Wang D, Yang H, De Braganca KC et al. (2008). The molec-

ular basis of pyruvate carboxylase deficiency: mosaicism

correlates with prolonged survival. Mol Genet Metab 95:31–38.

Weber TA, Antognetti MR, Stacpoole PW (2001). Caveats

when considering ketogenic diets for the treatment of pyru-

vate dehydrogenase complex deficiency. J Pediatr 138:390–395.

Wexler ID, Du Y, Lisgaris MV et al. (1994). Primary amino

acid sequence and structure of human pyruvate carboxyl-

ase. Biochim Biophys Acta 1227: 46–52.