RESEARCH ARTICLE Open Access
Molecular and biochemical characterisation of a
novel mutation in POLG associated with Alpers
André Schaller1*, Dagmar Hahn2, Christopher B Jackson1, Ilse Kern3, Christophe Chardot4,5, Dominique C Belli3,
Sabina Gallati1, Jean-Marc Nuoffer2
Background: DNA polymerase g (POLG) is the only known mitochondrial DNA (mtDNA) polymerase. It mediates
mtDNA replication and base excision repair. Mutations in the POLG gene lead to reduction of functional mtDNA
(mtDNA depletion and/or deletions) and are therefore predicted to result in defective oxidative phosphorylation
(OXPHOS). Many mutations map to the polymerase and exonuclease domains of the enzyme and produce a broad
clinical spectrum. The most frequent mutation p.A467T is localised in the linker region between these domains. In
compound heterozygote patients the p.A467T mutation has been described to be associated amongst others with
fatal childhood encephalopathy. These patients have a poorer survival rate compared to homozygotes.
Methods: mtDNA content in various tissues (fibroblasts, muscle and liver) was quantified using quantitative PCR
(qPCR). OXPHOS activities in the same tissues were assessed using spectrophotometric methods and catalytic stain
Results: We characterise a novel splice site mutation in POLG found in trans with the p.A467T mutation in a 3.5
years old boy with valproic acid induced acute liver failure (Alpers-Huttenlocher syndrome). These mutations result
in a tissue specific depletion of the mtDNA which correlates with the OXPHOS-activities.
Conclusions: mtDNA depletion can be expressed in a high tissue-specific manner and confirms the need to
analyse primary tissue. Furthermore, POLG analysis optimises clinical management in the early stages of disease and
reinforces the need for its evaluation before starting valproic acid treatment.
Mitochondria have their own small 16.5 kb circular dou-
ble stranded DNA encoding 22 tRNAs, 2 rRNAs and 13
polypeptides, that are absolutely essential for electron
transport and oxidative phosphorylation. The remaining
1000-1500 proteins required for mitochondrial biogenesis
are encoded by the nuclear genome and are imported
into the mitochondria . These include the proteins
involved in mitochondrial DNA (mtDNA) replication,
which, if defective, can produce mtDNA mutations lead-
ing to mitochondrial dysfunction and disease .
Among the 16 DNA polymerases identified in the eukar-
yotic cell so far, only DNA polymerase g (pol g) is known
to function in mitochondria [3-5]. The holoenzyme of
human pol g is composed of the catalytic subunit (encoded
by POLG at chromosomal locus 15q25) and a homodimer
of its accessory factor (encoded by POLG2 at chromosomal
locus 17q24.1) . Mutations in the POLG gene have
emerged as one of the most common causes of inherited
mitochondrial disease in children and adults. They are
responsible for a heterogeneous group of at least six major
phenotypes of neurodegenerative diseases that include: 1)
childhood Myocerebrohepathopathy Spectrum disorders
(MCHS), 2) Alpers syndrome , 3) Ataxia Neuropathy
Spectrum (ANS) disorders , 4) Myoclonus Epilepsy
Myopathy Sensory Ataxia (MEMSA), 5) autosomal reces-
sive Progressive External Ophthalmoplegia (arPEO), and 6)
autosomal dominant Progressive External Ophthalmople-
gia (adPEO) [9-11]. As a consequence of POLG failure,
* Correspondence: email@example.com
1Division of Human Genetics, University Hospital Bern, Bern, Switzerland
Full list of author information is available at the end of the article
Schaller et al. BMC Neurology 2011, 11:4
© 2011 Schaller et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
accumulation of multiple mtDNA deletions and/or deple-
tion of mtDNA in postmitotic tissues such as muscle, brain
and liver is noted . Additionally, various combinations
of OXPHOS complex deficiencies have been reported due
to POLG mutations [13-17].
Furthermore, recent studies in this area reinforced, in
particular, evidence that certain mutations in POLG can
lead to a range of clinical phenotypes which predispose
to development of fatal liver failure after exposure to
valproic acid (VPA) [15,18].
In this paper we describe the molecular genetic analy-
sis of POLG in a 3.5 years old boy with VPA induced
fatal liver failure (Alpers-Huttenlocher syndrome, AHS).
The consequences of the findings were further investi-
gated at molecular and biochemical levels.
A 3 7/12 year old boy, from non-consanguineous parents,
with global developmental delay and ataxia was treated
with valproate because of focal seizures with secondary
generalisation. After 2 months, he developed acute liver
failure (INR 29.95, PTT 68,9’’,fibrinogen <0.5 g/l, total
bilirubin 152 μmol/l, ASAT 169 U/L, ALAT 139 U/L,
NH3 124 μmol/l). AHS was diagnosed based on medical
history, and medical work-up demonstrated no other
causes of acute liver failure. Due to the unavoidable severe
progression of the neurological impairment, liver trans-
plantation[19-21] was not proposed and the child died
within two days. His parents gave informed consent for
genetic studies on the collected samples (blood, skin, mus-
cle and liver biopsies). The study protocol was approved
by the local ethic commission of Bern (KEK Nr. 84/02).
Mutation Analysis and DNA Sequencing
Genomic DNA was extracted from EDTA-stabilised
venous blood samples applying the QIAamp DNA kit
according to the manufacturer’s instructions. All 22 cod-
ing exons of the POLG were amplified from genomic
DNA by means of PCR using primers listed in additional
file 1. Mutation analysis of the amplified exons was per-
formed by SSCP as described previously . PCR pro-
ducts were sequenced employing BigDye Terminator
Chemistry (Applied Biosystems) and separated on an ABI
3100 DNA Sequencer. Data were analysed with SeqScape
version 2.1.1 software (Applied Biosystems).
Primary fibroblast cultures were established from a skin
biopsy and cultured in minimal essential medium
(MEM) supplemented with 10% fetal calf serum, 4
mmol/L l-glutamine, 2 μmol/L uridine, 1 μmol/L
sodium pyruvate, 50 U/ml penicillin, and 50 μg/ml
streptomycin at 37°C and 5% CO2.
Primary fibroblasts were grown for 8 h in 75 mM caf-
feine prior to preparation of RNA in order to minimise
nonsense mediated mRNA decay. Total RNA was iso-
lated using the QIAgen RNeasy Kit according to the
manufacturer’s instructions. Random oligohexamer
primed RNA (up to 1 μg) was reverse transcribed in a
final volume of 25 μl using the SuperScript II First-
Strand cDNA Synthesis System (Invitrogen) according
to the manufacturer’s recommendations. One-twenty-
fifth of single stranded cDNA was used as a template to
amplify the fragment spanning exons 5-9 of POLG using
the following two oligonucleotides: POLGex5 fwd 5’-
GCACCATGAAGGACATTCGT-3’ and POLGex9 rev
5’-GCCATGACATCTTGTTGAAACT-3’. Cycling con-
ditions using HotStar Taq DNA Polymerase (Qiagen)
were 95°C for 15 min, 32 cycles of 15 s at 95°C, 15 s at
58°C and 1 min at 72°C and a final extension step of 5
min at 72°C. RT-PCR products were separated on an
agarose gel and extracted for subsequent sequencing.
For determination of splicing efficiency of the c.1251-
2A > T allele, cDNA was synthesised using two oligonu-
cleotides spanning from exon 6 to exon 8: POLGex6
fwd 5’-TGTGCCCAGGACGTGTG-3’ and POLGex8 rev
5’-CCGAGGTCTTCCTGATCCAT-3’ essentially as
describe above. The RT-PCR product was subsequently
subcloned into pCR2.1-TOPO plasmid using the
TOPO-TA Cloining Kit (Invitrogen). Single colonies
were picked and inserts were directly amplified using
M13 forward and reverse primers and subjected to
DNA sequencing as described above.
Total genomic DNA from muscle, liver and fibroblast spe-
cimens were isolated using the QIAamp DNA kit accord-
ing to the manufacturer’s instructions. Mitochondrial
DNA content was determined by real-time PCR essentially
as described by Bai and Wong  using SYBR Green
fluorescence dye for detection of amplification. The
sequence for reverse primer D-loop was replaced by the
following oligonucleotide: 5’-CCGTGAGTGGTTAA-
TAGGGTG-3’. The real-time PCR reactions for each
locus (D-loop, tRNALeuUUR, ND4, ATP8 and b2 M)
were performed in duplicate in 20 μl reactions containing
10 μl SYBR®Premix ExTaq (Perfect real time, Takara Bio
USA), 0.5 μM of each primer for a corresponding target
region and 4 ng of total genomic DNA. Real time PCR
conditions were 5 min at 95°, followed by 40 cycles of 30 s
at 95°C, 15 s at 60°C and 10 s at 72°C. Fluorescent signal
intensity of PCR products was recorded and analysed on a
LightCycler 480 instrument (Roche Diagnostics) using
LightCycler®480 software. The threshold cycle or CT
value within the linear exponential phase was used to con-
struct the standard curve and to measure the original copy
Schaller et al. BMC Neurology 2011, 11:4
Page 2 of 7
number of DNA template. Fibroblasts control values were
established from patients with circumcisions or auriculo-
plasty, muscle and liver controls were from biopsies of
patients without clinical and biochemical suspicion of a
Isolation of mitochondria from skin fibroblasts, prepara-
tion of skeletal muscle- and liver homogenates (600 g
supernatants) were performed as described [24,25]. The
activities of the individual respiratory chain complexes
and the mitochondrial matrix marker enzyme citrate
synthase were measured spectrophotometrically with an
UV-1601 spectrophotometer (Shimadzu) using 1 ml
sample cuvettes thermostatically maintained at 30°C
according to Birch-Machin and Douglas . Values
were estimated by the difference in activity levels mea-
sured in the presence and absence of specific inhibitors
and expressed as ratios to the mitochondrial marker
enzyme citrate synthase (mU/mU citrate synthase),
which was determined as described . Fibroblasts
control values were established from patients with cir-
cumcisions or auriculoplasty, muscle and liver controls
were from biopsies of patients without clinical and bio-
chemical suspicion of a mitochondrial disorders.
For catalytic in gel staining, 600 g supernatants of
muscle- and liver homogenates were centrifuged (30
min, 4°C,13000 rpm) and the oxidative phosphorylation
complexes were solubilised by 5 mg digitonin per mg
protein before separation by BN-PAGE as recommended
. For the first dimension gradient gels of 4.5 - 13%
were used. Catalytic staining of strips of the first dimen-
sion were performed as reported .
Sequence analysis of patients DNA revealed compound
heterozygosity for mutations in POLG. Beside the most
common POLG mutation c.1399G > A/p.A467T (Figure
1A), a novel splice site mutation in intron 6 was identi-
fied (c.1251-2A > T) (Figure 1B). The splice site mutation
C T G G C C A A T
T C C A A G G T G
intron 6 exon 7
exon 6 exon 8
T G G A G A G G T A C T T T
- exons 6,7,8
- exons 6, 8
Figure 1 Molecular genetic analysis of POLG. a) Electropherogram showing the presence or absence of the novel splice site mutation in
intron 6 of the patient, his parents and the prenatal diagnosis in the gDNA. b) Electropherogram showing the presence or absence of the p.
A467T mutation in exon 7 of the patient, his parents and the prenatal diagnosis in the gDNA. c) Electropherogram showing aberrantly spliced
POLG mRNA lacking exon 7 by sequencing the gel isolated lower band derived from patient’s lane in d). d) Agarose gel showing POLG
transcript analysis POLG mRNA derived from fibroblasts. An aberrant splicing product lacking exon 7 is detected in patients cDNA. e) Pedigree of
the family including the genotype.
Schaller et al. BMC Neurology 2011, 11:4
Page 3 of 7
results in exon 7 skipping (Figure 1C,D), but does not
affect the reading-frame, hence, the aberrantly spliced
POLG transcript should not be vulnerable to undergo
nonsense mediated RNA decay (NMD). To assess the
degree of exon skipping for the c.1251-2A > T allele PCR
products derived from POLG cDNA spanning exons 6-8
were subcloned and individual clones analysed. 77 indivi-
dual clones revealed that 45% (34/77) of the transcripts
were correctly spliced, while 55% (43/77) were aberrantly
spliced. Furthermore, sequence analysis of the correctly
spliced transcripts all harboured the p.A467T mutation
suggesting that correct splicing of the c.1251-2A > T
allele is completely impaired. In addition, these results
also confirm that both alleles are approximately equally
expressed and that indeed no NMD of the aberrantly
spliced c.1251-2A > T allele occurs.
Molecular genetic testing of the patient’s parents iden-
tified his father as a carrier of the novel c.1251-2A > T
splice site mutation (Figure 1A and 1E) and his mother
as a heterozygous carrier of the p.A467T mutation (Fig-
ure 1B and 1E).
To further investigate the consequences of the POLG
mutations, the mtDNA was quantitatively and qualitatively
assessed using a combined qPCR approach. The analysis
of DNA extracted from fibroblasts, liver and skeletal mus-
cle revealed no deletions in the mtDNA in the tissues
tested (results not shown). However, various degrees of
mtDNA depletion were detected in the three tested tissues
(Figure 2). In fibroblasts, the amount of mtDNA (820
molecules per cell) was insignificantly lower relative to the
control mean (832 molecules per cell) (Figure 2A),
whereas a mtDNA depletion of 22% was detected in mus-
cle relative to the control mean (Figure 2B). The most pro-
nounced mtDNA depletion was measured in the patient’s
liver tissue where 85% of the mtDNA was depleted relative
to the control mean (Figure 2C).
In order to assess the consequences of the mtDNA deple-
tion on the OXPHOS activities, CI-V have been assayed. In
the mitochondria from patient’s fibroblasts, liver- and skele-
tal muscle tissues, OXPHOS enzymes (I, II, III, IV and V)
were measured spectrophotometrically. In fibroblasts all
activities were normal. The activities of complex I, III and
IV were decreased in liver. In skeletal muscle, the activity of
complex IV was decreased and the activities for complex I
and II were in the lower control range (table 1). Catalytic
staining in the BN-PAGE gel revealed a severe reduction of
intensity for complex IV in liver and muscle (Figure 3). The
intensities for complex I were also reduced in both tissues,
but to a lesser extent. Staining for complex II was normal
and comparable to the control (Figure 3).
Mitochondrial depletion syndromes (MDS) are severe
disorders often presenting themselves in early infancy or
childhood. They comprise of a variety of features includ-
ing profound weakness, encephalopathy, seizures and
liver failure. A particular form of a hepatocerebral deple-
tion is known as Alpers-Huttenlocher Syndrome (AHS)
characterised by progressive neuronal degeneration in
childhood, explosive onset of seizures, developmental
mtDNA / nDNA
mtDNA / nDNA
mtDNA / nDNA
Figure 2 Quantification of mtDNA. Quantification of mtDNA
depletion in muscle, liver and fibroblasts of the patient. mtDNA
content was measured by qPCR and normalised to a nuclear gene
(B2M). Control mean and +/-1SD: fibroblast 832 +/-280; skeletal
muscle 2878 +/-766 and liver 1515 +/-192.
Schaller et al. BMC Neurology 2011, 11:4
Page 4 of 7
delay, cortical blindness and spasticity followed by ful-
minant liver failure and parieto-occipital cerebral atro-
phy . In AHS a depletion of the mtDNA is
commonly observed, which is considered as a secondary
phenomenon due to primary POLG mutations, which in
turn leads to a defective system for oxidative phosphory-
lation (OXPHOS) . However, POLG mutations in
these phenotypes are not exclusive to the observed
Currently, there is no clear link between a particular
POLG genotype and the resulting phenotype. However,
with the characterisation of an increasing number of
reported POLG mutations, patterns start to emerge. All
AHS affected patients reported so far carry one of two
linker mutations (p.A467T or p.W748S) in combination
with either another linker mutation or a mutation
located in the polymerase domain , whereas the p.
A467T mutation is the most common mutation identi-
fied in POLG. It is present in all major POLG-related
diseases: Alpers-Huttenlocher disease, ataxia-neuropathy
syndromes and PEO.
Our patient showed a severe clinical phenotype and
died due to valproate induced fatal acute liver failure.
Analysis of the mtDNA content revealed a severe
depletion in liver (approx. 90%), a less pronounced
depletion in skeletal muscle (approx. 25%) and no deple-
tion in fibroblasts. As a consequence, a combined
respiratory chain defect involving complexes I, III and
IV was measured in liver cells. In skeletal muscle, only
complex IV showed a decreased activity suggesting that
complex IV is the most vulnerable in mtDNA depletion
syndromes. However, it is unknown which factors con-
tribute to the tissue specificity of mitochondrial dysfunc-
tion in patients carrying POLG mutations. The finding
of normal OXPHOS enzyme activities in our patient is
also a common observation in other patients  and
emphasises the need to investigate primary tissues as
fibroblast analysis may give misleading results. The cel-
lular mtDNA content may be an indicator of the under-
lying molecular mechanism linking genotype to
phenotype and explaining the patient’s acute liver
Molecular genetic analysis of POLG revealed two lin-
ker region mutations, the c.1399G > A (p.A467T) and a
novel splice site mutation c.1251-2A > T affecting the
highly conserved splice acceptor site in intron 6. Analy-
sis of the patient’s parents confirmed that these muta-
tions are present in trans in the patient. These findings
are in good agreement with the observation that patients
with two linker mutations exhibit a more severe clinical
phenotype than patients carrying one linker and one
polymerase domain mutation . Furthermore, detec-
tion of the primary mutations in POLG did not only
confirm the clinical diagnosis of Alpers syndrome, but
also allowed a reliable prenatal diagnosis for the parents
in the following pregnancy (Figure 1A and 1B).
Several inborn errors of metabolism are known to
represent a risk factor for severe idiosyncratic reactions
to VPA, including liver toxicity . Many studies have
focused on the interaction between VPA and mitochon-
drial function in general and mitochondrial disorders
such as Alpers-Syndrome in particular, as conditions
predisposing to severe VPA toxicity . Recent studies
gave evidence that POLG mutations can lead to a range
of clinical phenotypes which predispose to the develop-
ment of fatal liver failure after exposure to VPA [15,18].
Table 1 Patient’s OXPHOS activities measured in three different tissues
EnzymesPatientControls (n = 22)
Skeletal muscle homogenate
PatientControls (n = 26)
Controls (n = 12)Patient
0.19 - 0.46 (0.29 +/- 0.07)
0.17 - 0.52 (0.33 +/- 0.09)
0.35 - 0.87 (0.6 +/- 0.15)
0.42 - 1.11 (0.75 +/- 0.18)
0.14 - 0.42 (0.22 +/- 0.08)
106 - 317 (184 +/- 43)
0.12 - 0.28 (0.19 +/- 0.04)
0.14 - 0.36 (0.21 +/- 0.05)
0.55 - 1.11 (1.16 +/- 0.28)
0.57 - 1.77 (0.78 +/- 0.15)
0.19 - 0.65 (0.39 +/- 0.13)
70 - 169 (105 +/- 25)
0.22 - 0.76 (0.43 +/- 0.2)
0.59 - 2.11 (1.35 +/- 0.45)
0.54 - 2.16 (1.47 +/- 0.49)
0.74 - 5.17 (2.1 +/- 1.2)
0.25 - 1.14 (0.58 +/- 0.28)
21 - 40 (31 +/- 6.5)
Activities of the respiratory chain complexes are normalised to citrate synthase (CS) and are expressed as mU/mg mitochondrial protein. Mean value (+/- 1SD) of
controls are indicated in brackets. Profound deficiencies below the range of controls are shown in bold. n = number of controls; * = measured as duplicate.
Figure 3 Catalytic staining of OXPHOS-complexes. Catalytic
staining following separation of the OXPHOS-complexes by BN-
PAGE showing decreased intensities of the bands corresponding to
complex I and IV in patients liver and skeletal muscle. The bands
corresponding to complex II are comparable to the control.
Schaller et al. BMC Neurology 2011, 11:4
Page 5 of 7
Nevertheless, a single case report suggests that there
may be mutations in the POLG gene associated with
reversibility of the hepatotoxicity , The presented
study extends the list of POLG mutations associated
with VPA hepatotoxicity.
Screening of POLG gene in mitochondrial diseases is
helpful for confirming the diagnosis, especially in the
case of AHS. POLG analysis offers the added benefits of
carrier testing, prenatal diagnosis, postnatal pre-sympto-
matic diagnosis of siblings and optimised clinical man-
agement from the early stages of disease. Further this
study contributes to the pathomechanism of POLG
mutations and expands the knowledge of the genotype-
Additional file 1: Primer sequences for PCR amplification of POLG
We are indebted to the family participating in this study. We thank A.
Häberli for excellent technical assistance. This work was supported by a
grant of the Novartis Research Foundation to AS.
1Division of Human Genetics, University Hospital Bern, Bern, Switzerland.
2Institute of Clinical Chemistry, University Hospital Bern, Bern, Switzerland.
3Department of Paediatrics, University of Geneva Children’s Hospital, Geneva,
Switzerland.4Paediatric Surgery Unit, University of Geneva Children’s
Hospital, Geneva, Switzerland.5Paediatric Surgery Unit, Hôpital Necker-
Enfants malades, Paris, France.
AS participated in the design and coordination of the study, performed
genetic and data analyses and drafted the manuscript. CBJ performed
genetic and data analyses and participated in drafting the manuscript. DH
and JMN performed biochemical and data analyses and participated in the
study design and in drafting the manuscript. IK, CC and DCB performed the
clinical investigations and participated in its design and in drafting the
manuscript. SG participated in genetic data analyses and in the design and
drafting the manuscript. All authors read and approved the final manuscript
This study has been funded by an unrestricted grant from Novartis. The
authors have no conflict of interest with the source of funding of the study.
Received: 20 June 2010 Accepted: 14 January 2011
Published: 14 January 2011
1.Calvo S, Jain M, Xie X, Sheth SA, Chang B, Goldberger OA, Spinazzola A,
Zeviani M, Carr SA, Mootha VK: Systematic identification of human
mitochondrial disease genes through integrative genomics. Nat Genet
2. Copeland WC: Inherited mitochondrial diseases of DNA replication. Annu
Rev Med 2008, 59:131-146.
3.Bebenek K, Kunkel TA: Functions of DNA polymerases. Adv Protein Chem
4.Ropp PA, Copeland WC: Cloning and characterization of the human
mitochondrial DNA polymerase, DNA polymerase gamma. Genomics
Sweasy JB, Lauper JM, Eckert KA: DNA polymerases and human diseases.
Radiat Res 2006, 166(5):693-714.
Yakubovskaya E, Chen Z, Carrodeguas JA, Kisker C, Bogenhagen DF:
Functional human mitochondrial DNA polymerase gamma forms a
heterotrimer. J Biol Chem 2006, 281(1):374-382.
Naviaux RK, Nguyen KV: POLG mutations associated with Alpers’
syndrome and mitochondrial DNA depletion. Ann Neurol 2004,
Winterthun S, Ferrari G, He L, Taylor RW, Zeviani M, Turnbull DM,
Engelsen BA, Moen G, Bindoff LA: Autosomal recessive mitochondrial
ataxic syndrome due to mitochondrial polymerase gamma mutations.
Neurology 2005, 64(7):1204-1208.
Lamantea E, Tiranti V, Bordoni A, Toscano A, Bono F, Servidei S,
Papadimitriou A, Spelbrink H, Silvestri L, Casari G, et al: Mutations of
mitochondrial DNA polymerase gammaA are a frequent cause of
autosomal dominant or recessive progressive external ophthalmoplegia.
Ann Neurol 2002, 52(2):211-219.
Van Goethem G, Dermaut B, Lofgren A, Martin JJ, Van Broeckhoven C:
Mutation of POLG is associated with progressive external
ophthalmoplegia characterized by mtDNA deletions. Nat Genet 2001,
Van Goethem G, Martin JJ, Dermaut B, Lofgren A, Wibail A, Ververken D,
Tack P, Dehaene I, Van Zandijcke M, Moonen M, et al: Recessive POLG
mutations presenting with sensory and ataxic neuropathy in compound
heterozygote patients with progressive external ophthalmoplegia.
Neuromuscul Disord 2003, 13(2):133-142.
Milone M, Brunetti-Pierri N, Tang LY, Kumar N, Mezei MM, Josephs K,
Powell S, Simpson E, Wong LJ: Sensory ataxic neuropathy with
ophthalmoparesis caused by POLG mutations. Neuromuscul Disord 2008,
Ferrari G, Lamantea E, Donati A, Filosto M, Briem E, Carrara F, Parini R,
Simonati A, Santer R, Zeviani M: Infantile hepatocerebral syndromes
associated with mutations in the mitochondrial DNA polymerase-
gammaA. Brain 2005, 128(Pt 4):723-731.
Gonzalez-Vioque E, Blazquez A, Fernandez-Moreira D, Bornstein B, Bautista J,
Arpa J, Navarro C, Campos Y, Fernandez-Moreno MA, Garesse R, et al:
Association of novel POLG mutations and multiple mitochondrial DNA
deletions with variable clinical phenotypes in a Spanish population. Arch
Neurol 2006, 63(1):107-111.
Horvath R, Hudson G, Ferrari G, Futterer N, Ahola S, Lamantea E, Prokisch H,
Lochmuller H, McFarland R, Ramesh V, et al: Phenotypic spectrum
associated with mutations of the mitochondrial polymerase gamma
gene. Brain 2006, 129(Pt 7):1674-1684.
de Vries MC, Rodenburg RJ, Morava E, van Kaauwen EP, ter Laak H,
Mullaart RA, Snoeck IN, van Hasselt PM, Harding P, van den Heuvel LP, et al:
Multiple oxidative phosphorylation deficiencies in severe childhood
multi-system disorders due to polymerase gamma (POLG1) mutations.
Eur J Pediatr 2007, 166(3):229-234.
Sarzi E, Bourdon A, Chretien D, Zarhrate M, Corcos J, Slama A, Cormier-
Daire V, de Lonlay P, Munnich A, Rotig A: Mitochondrial DNA depletion is
a prevalent cause of multiple respiratory chain deficiency in childhood. J
Pediatr 2007, 150(5):531-534, 534 e531-536.
Tzoulis C, Engelsen BA, Telstad W, Aasly J, Zeviani M, Winterthun S,
Ferrari G, Aarseth JH, Bindoff LA: The spectrum of clinical disease caused
by the A467T and W748S POLG mutations: a study of 26 cases. Brain
2006, 129(Pt 7):1685-1692.
Nguyen KV, Ostergaard E, Ravn SH, Balslev T, Danielsen ER, Vardag A,
McKiernan PJ, Gray G, Naviaux RK: POLG mutations in Alpers syndrome.
Neurology 2005, 65(9):1493-1495.
Delarue A, Paut O, Guys JM, Montfort MF, Lethel V, Roquelaure B,
Pellissier JF, Sarles J, Camboulives J: Inappropriate liver transplantation in
a child with Alpers-Huttenlocher syndrome misdiagnosed as valproate-
induced acute liver failure. Pediatr Transplant 2000, 4(1):67-71.
Thomson M, McKiernan P, Buckels J, Mayer D, Kelly D: Generalised
mitochondrial cytopathy is an absolute contraindication to orthotopic
liver transplant in childhood. J Pediatr Gastroenterol Nutr 1998,
Schaller et al. BMC Neurology 2011, 11:4
Page 6 of 7
22.Liechti-Gallati S, Schneider V, Neeser D, Kraemer R: Two buffer PAGE Download full-text
system-based SSCP/HD analysis: a general protocol for rapid and
sensitive mutation screening in cystic fibrosis and any other human
genetic disease. Eur J Hum Genet 1999, 7(5):590-598.
Bai RK, Wong LJ: Simultaneous detection and quantification of
mitochondrial DNA deletion(s), depletion, and over-replication in
patients with mitochondrial disease. J Mol Diagn 2005, 7(5):613-622.
Rustin P, Chretien D, Bourgeron T, Gerard B, Rotig A, Saudubray JM,
Munnich A: Biochemical and molecular investigations in respiratory
chain deficiencies. Clin Chim Acta 1994, 228(1):35-51.
Birch-Machin MA, Turnbull DM: Assaying mitochondrial respiratory
complex activity in mitochondria isolated from human cells and tissues.
Methods Cell Biol 2001, 65:97-117.
Shepherd D, Garland PB: The kinetic properties of citrate synthase from
rat liver mitochondria. Biochem J 1969, 114(3):597-610.
Schagger H: Blue-native gels to isolate protein complexes from
mitochondria. Methods Cell Biol 2001, 65:231-244.
Zerbetto E, Vergani L, Dabbeni-Sala F: Quantification of muscle
mitochondrial oxidative phosphorylation enzymes via histochemical
staining of blue native polyacrylamide gels. Electrophoresis 1997,
Huttenlocher PR, Solitare GB, Adams G: Infantile diffuse cerebral
degeneration with hepatic cirrhosis. Arch Neurol 1976, 33(3):186-192.
Stewart JD, Tennant S, Powell H, Pyle A, Blakely EL, He L, Hudson G,
Roberts M, du Plessis D, Gow D, et al: Novel POLG1 mutations associated
with neuromuscular and liver phenotypes in adults and children. J Med
Genet 2009, 46(3):209-214.
Konig SA, Siemes H, Blaker F, Boenigk E, Gross-Selbeck G, Hanefeld F,
Haas N, Kohler B, Koelfen W, Korinthenberg R, et al: Severe hepatotoxicity
during valproate therapy: an update and report of eight new fatalities.
Epilepsia 1994, 35(5):1005-1015.
Silva MF, Aires CC, Luis PB, Ruiter JP, Ijlst L, Duran M, Wanders RJ, Tavares
de Almeida I: Valproic acid metabolism and its effects on mitochondrial
fatty acid oxidation: A review. J Inherit Metab Dis 2008, 31(2):205-216.
McFarland R, Hudson G, Taylor RW, Green SH, Hodges S, McKiernan PJ,
Chinnery PF, Ramesh V: Reversible valproate hepatotoxicity due to
mutations in mitochondrial DNA polymerase gamma (POLG1). Arch Dis
Child 2008, 93(2):151-153.
The pre-publication history for this paper can be accessed here:
Cite this article as: Schaller et al.: Molecular and biochemical
characterisation of a novel mutation in POLG associated with Alpers
syndrome. BMC Neurology 2011 11:4.
Submit your next manuscript to BioMed Central
and take full advantage of:
• Convenient online submission
• Thorough peer review
• No space constraints or color figure charges
• Immediate publication on acceptance
• Inclusion in PubMed, CAS, Scopus and Google Scholar
• Research which is freely available for redistribution
Submit your manuscript at
Schaller et al. BMC Neurology 2011, 11:4
Page 7 of 7