A Nonsense Mutation in DHTKD1 Causes Charcot-Marie-Tooth Disease Type 2 in a Large Chinese Pedigree
2012; Elsevier BV; Volume: 91; Issue: 6 Linguagem: Inglês
10.1016/j.ajhg.2012.09.018
ISSN1537-6605
AutoresWangyang Xu, Ming-min Gu, Lianhua Sun, Wenting Guo, Houbao Zhu, Jianfang Ma, Wentao Yuan, Ying Kuang, JI Baojun, Xiaolin Wu, Yan Chen, Hongxin Zhang, Futing Sun, Wei Huang, Lei Huang, Shengdi Chen, Zhugang Wang,
Tópico(s)Neurological diseases and metabolism
ResumoCharcot-Marie-Tooth (CMT) disease represents a clinically and genetically heterogeneous group of inherited neuropathies. Here, we report a five-generation family of eight affected individuals with CMT disease type 2, CMT2. Genome-wide linkage analysis showed that the disease phenotype is closely linked to chromosomal region 10p13-14, which spans 5.41 Mb between D10S585 and D10S1477. DNA-sequencing analysis revealed a nonsense mutation, c.1455T>G (p.Tyr485∗), in exon 8 of dehydrogenase E1 and transketolase domain-containing 1 (DHTKD1) in all eight affected individuals, but not in other unaffected individuals in this family or in 250 unrelated normal persons. DHTKD1 mRNA expression levels in peripheral blood of affected persons were observed to be half of those in unaffected individuals. In vitro studies have shown that, compared to wild-type mRNA and DHTKD1, mutant mRNA and truncated DHTKD1 are significantly decreased by rapid mRNA decay in transfected cells. Inhibition of nonsense-mediated mRNA decay by UPF1 silencing effectively rescued the decreased levels of mutant mRNA and protein. More importantly, DHTKD1 silencing was found to lead to impaired energy production, evidenced by decreased ATP, total NAD+ and NADH, and NADH levels. In conclusion, our data demonstrate that the heterozygous nonsense mutation in DHTKD1 is one of CMT2-causative genetic alterations, implicating an important role for DHTKD1 in mitochondrial energy production and neurological development. Charcot-Marie-Tooth (CMT) disease represents a clinically and genetically heterogeneous group of inherited neuropathies. Here, we report a five-generation family of eight affected individuals with CMT disease type 2, CMT2. Genome-wide linkage analysis showed that the disease phenotype is closely linked to chromosomal region 10p13-14, which spans 5.41 Mb between D10S585 and D10S1477. DNA-sequencing analysis revealed a nonsense mutation, c.1455T>G (p.Tyr485∗), in exon 8 of dehydrogenase E1 and transketolase domain-containing 1 (DHTKD1) in all eight affected individuals, but not in other unaffected individuals in this family or in 250 unrelated normal persons. DHTKD1 mRNA expression levels in peripheral blood of affected persons were observed to be half of those in unaffected individuals. In vitro studies have shown that, compared to wild-type mRNA and DHTKD1, mutant mRNA and truncated DHTKD1 are significantly decreased by rapid mRNA decay in transfected cells. Inhibition of nonsense-mediated mRNA decay by UPF1 silencing effectively rescued the decreased levels of mutant mRNA and protein. More importantly, DHTKD1 silencing was found to lead to impaired energy production, evidenced by decreased ATP, total NAD+ and NADH, and NADH levels. In conclusion, our data demonstrate that the heterozygous nonsense mutation in DHTKD1 is one of CMT2-causative genetic alterations, implicating an important role for DHTKD1 in mitochondrial energy production and neurological development. Charcot-Marie-Tooth (CMT) disease is one of the most common inherited neurological disorders.1Charcot J.M. Marie P. Sur une form particuliere d'atrophie musculaire progressive, souvant familiale, debutant par les pieds et les jambes, et atteignant plus tard les mains.Rev. Med. (Paris). 1886; 6: 97-138Google Scholar, 2Tooth H.H. The peroneal type of progressive muscular atrophy. H. K. Lewis, London1886Google Scholar Individuals with CMT experience symmetric, slowly progressive distal motor neuropathy of the arms and legs; this usually begins in the first to third decade of life and results in weakness and atrophy of the muscles in the feet and/or hands. Clinically, CMT can be divided into two major phenotypic types: a demyelinating form (CMT disease type 1) affecting the glia-derived myelin and an axonal form (CMT disease type 2 [CMT2]) affecting the nerve axon.3Pareyson D. Scaioli V. Laurà M. Clinical and electrophysiological aspects of Charcot-Marie-Tooth disease.Neuromolecular Med. 2006; 8: 3-22Crossref PubMed Scopus (144) Google Scholar, 4Banchs I. Casasnovas C. Albertí A. De Jorge L. Povedano M. Montero J. Martínez-Matos J.A. Volpini V. Diagnosis of Charcot-Marie-Tooth disease.J. Biomed. Biotechnol. 2009; 2009: 985415Crossref PubMed Scopus (56) Google Scholar Genetically, mutant alleles underlying CMT can segregate in an autosomal-dominant, recessive, or X-linked manner involving 43 unique genes.5Saporta A.S. Sottile S.L. Miller L.J. Feely S.M. Siskind C.E. Shy M.E. Charcot-Marie-Tooth disease subtypes and genetic testing strategies.Ann. Neurol. 2011; 69: 22-33Crossref PubMed Scopus (388) Google Scholar, 6Lupski J.R. Reid J.G. Gonzaga-Jauregui C. Rio Deiros D. Chen D.C.Y. Nazareth L. Bainbridge M. Dinh H. Jing C. Wheeler D.A. et al.Whole-genome sequencing in a patient with Charcot-Marie-Tooth neuropathy.N. Engl. J. Med. 2010; 362: 1181-1191Crossref PubMed Scopus (614) Google Scholar The overall prevalence of CMT is estimated at 1–5 in 10,000 individuals. CMT2 represents 25%–30% (1:10,000) of all CMT cases characterized by distal muscle weakness and atrophy, mild sensory loss, and normal or near-normal nerve conduction velocities.7Puwanant A. Herrmann D.N. Hereditary motor sensory neuropathies (Charcot-Marie-Tooth disease) in neuromuscular disorders.in: Tawil R. Venance S. Wiley-Blackwell, Hoboken, USA2011: 165Google Scholar The median motor conduction velocity is above 38 m/s (GeneReviews in Web Resources). Until now, mutations in 15 unique genes have been identified as causing CMT28Züchner S. Vance J.M. Molecular genetics of autosomal-dominant axonal Charcot-Marie-Tooth disease.Neuromolecular Med. 2006; 8: 63-74Crossref PubMed Scopus (67) Google Scholar, 9Patzkó Á. Shy M.E. Update on Charcot-Marie-Tooth disease.Curr. Neurol. Neurosci. Rep. 2011; 11: 78-88Crossref PubMed Scopus (117) Google Scholar, 10McLaughlin H.M. Sakaguchi R. Giblin W. Wilson T.E. Biesecker L. Lupski J.R. Talbot K. Vance J.M. Züchner S. Lee Y.C. et al.NISC Comparative Sequencing ProgramA recurrent loss-of-function alanyl-tRNA synthetase (AARS) mutation in patients with Charcot-Marie-Tooth disease type 2N (CMT2N).Hum. Mutat. 2012; 33: 244-253Crossref PubMed Scopus (76) Google Scholar (also see GeneReviews in Web Resources). All these subtypes of CMT2 are similar clinically and are distinguished mainly by molecular-genetic findings. More importantly, the genetic mutations in most CMT2-associated genes have been found to lead to defects in mitochondrial function or axonal transport, the most likely hypothesis explaining the observation that axonal degeneration is maximal at distal nerve endings. Impairment of mitochondrial function has been put forward as a general critical component of the disease mechanisms in hereditary neuropathies because the defects in mitochondrial function or axonal transport could dramatically affect the peripheral nerves by depriving the distal axon of a needed source of energy.11Niemann A. Berger P. Suter U. Pathomechanisms of mutant proteins in Charcot-Marie-Tooth disease.Neuromolecular Med. 2006; 8: 217-242Crossref PubMed Scopus (152) Google Scholar, 12Cassereau J. Chevrollier A. Gueguen N. Desquiret V. Verny C. Nicolas G. Dubas F. Amati-Bonneau P. Reynier P. Bonneau D. Procaccio V. Mitochondrial dysfunction and pathophysiology of Charcot-Marie-Tooth disease involving GDAP1 mutations.Exp. Neurol. 2011; 227: 31-41Crossref PubMed Scopus (73) Google Scholar In the present work, we report a five-generation family (from the Shandong Province of China) affected by autosomal-dominant CMT2. This family was ascertained through initial identification of the proband (IV-25 in Figure 1A). The study was approved by the committee of Basic Medicine Faculty at Shanghai Jiao Tong University School of Medicine. After informed consent was obtained, all family members who agreed to participate in this study were evaluated by experienced neurologists. All affected individuals (five males and three females) presented with certain typical CMT2 phenotypes, including symmetrical muscle wasting and a predominating weakness of the distal parts of the lower limbs, decreased or absent deep-tendon reflexes, and mild to moderate deep sensory impairment. The clinical records and CMT neuropathy scores of all affected individuals are shown in Table S1,13Murphy S.M. Herrmann D.N. McDermott M.P. Scherer S.S. Shy M.E. Reilly M.M. Pareyson D. Reliability of the CMT neuropathy score (second version) in Charcot-Marie-Tooth disease.J. Peripher. Nerv. Syst. 2011; 16: 191-198Crossref PubMed Scopus (231) Google Scholar available online. For confirmation of the diagnosis, the proband was carefully examined in Rui-Jin Hospital. The initial complaints of the proband included difficulty walking and tripping due to foot and distal leg weakness at the age of 15 years. Neurological examination revealed muscle atrophy in the distal parts of forearm and interosseous muscles of the hands (Figure 1B). His lower legs developed severe muscle atrophy, which presented as "crane-leg-like" malformations (Figure 1C). On electrophysiological examination, both motor-nerve conduction velocities (MNCVs) and sensory-nerve conduction velocities (SNCVs) were normal (>52.4 m/s) in the upper limbs. In his lower limbs, MNCVs seemed to be reduced (38.9–40.4 m/s), but SNCVs were normal (>46.4 m/s). Such fluctuation in MNCVs in the proband seems, to some degree, to reflect the heterogeneity in neuropathological alteration of CMT2. The compound motor action potentials were reduced in amplitude in his upper and lower limbs. For histological analysis, a muscle sample was taken from the biceps brachii muscle of individual IV-25. Some small, angulated muscle fibers were found with the use of hematoxylin and eosin staining (Figure 1D). Electron microscopy showed sarcomere disappearance, disorganized myofilaments, and mitochondrial vacuolization in muscle cells (Figure 1E). These electrophysiological and morphological findings are characteristic of an axonal CMT phenotype. Considering the genetic heterogeneity of CMT2, we directly performed a genome-wide scan by using 401 markers that cover the human genome at 10 cM average resolution. The results showed no linkage to any known loci for CMT2 (Table S2). However, we were able to identify in chromosomal region 10p13-14 a single locus that cosegregated with the disease (Table S3). Further genotype and haplotype analyses (Figure S1) narrowed the linkage region to a 5.41 Mb interval between markers D10S585 and D10S1477 (maximum two-point LOD score = 4.56 at θ = 0.0 at D10S506). This genetic interval encompasses 20 candidate genes (Figure S2). To find the disease-associated gene, we first considered phytanoyl-CoA hydroxylase (PHYH [MIM 602026]), located in chromosomal region 10p13. The gene was previously reported to be associated with hereditary motor and sensory neuropathy IV (HSMN4 [MIM 266500]) with autosomal-recessive inheritance.14Jansen G.A. Wanders R.J. Watkins P.A. Mihalik S.J. Phytanoyl-coenzyme A hydroxylase deficiency—The enzyme defect in Refsum's disease.N. Engl. J. Med. 1997; 337: 133-134Crossref PubMed Scopus (92) Google Scholar Sequencing analysis of PHYH (RefSeq accession number NM_006214.3) revealed an identical wild-type sequence in affected individuals and control subjects. Therefore, PHYH was ruled out as a candidate gene in this pedigree. We further selected 19 other candidate genes within this region for sequencing analysis. Among these candidate genes screened, we finally identified a nonsense mutation, c.1455T>G (p.Tyr485∗), in exon 8 of dehydrogenase E1 and transketolase domain-containing 1 (DHTKD1 [RefSeq NM_018706.5]) in only eight affected individuals of this family. Such genetic mutation was not detected in unaffected members in the family or in 250 unrelated, ethnically matched individuals (i.e., 500 chromosomes). We also checked DHTKD1 sequence information in the database of the 1000 Genomes Project. No such variation (c.1455T>G) in DHTKD1 was found. To confirm the involvement of DHTKD1 in CMT2, we screened ten unrelated CMT2-affected individuals from eight independent pedigrees for the mutations in DHTKD1. However, no mutations were observed in these affected individuals. These data suggest that the DHTKD1 mutation (c.1455T>G) is a disease-associated genetic variation cosegregating with the CMT2 phenotype in this family. DHTKD1 is presumed to be a nuclear-encoded mitochondrial precursor protein, also named "probable 2-oxoglutarate dehydrogenase E1 component DHTKD1." Its physiological function remains largely unknown to date.15Bunik V.I. Degtyarev D. Structure-function relationships in the 2-oxo acid dehydrogenase family: substrate-specific signatures and functional predictions for the 2-oxoglutarate dehydrogenase-like proteins.Proteins. 2008; 71: 874-890Crossref PubMed Scopus (63) Google Scholar DHTKD1 is localized in chromosomal region 10p14, which is between D10S585 and D10S1705 (Figure 2A). There are 17 exons with an open reading frame of 5,202 bp, encoding a peptide of 919 amino acids (Figure 2B).16Venter J.C. Adams M.D. Myers E.W. Li P.W. Mural R.J. Sutton G.G. Smith H.O. Yandell M. Evans C.A. Holt R.A. et al.The sequence of the human genome.Science. 2001; 291: 1304-1351Crossref PubMed Scopus (10566) Google Scholar BLAST comparison of the sequence from amino acids 470–501 in orthologs of DHTKD1 among species revealed that the amino acids from 483 to 485 are highly conserved except in Drosophila melanogaster and Caenorhabditis elegans (Figure 2C). The T to G transition at nucleotide position 1,455 presumably causes an amino acid change from tyrosine (TAT) to a stop codon (TAG) at the 485th amino acid residue (Figures 2C and 2D). With PyMOL software, computer simulation of the three-dimensional structure of DHTKD1 revealed a truncated protein missing the 435 C-terminal residues (Figures 2E and 2F). To evaluate the effect of the mutant DHTKD1 expression, we tested mRNA expression levels in the peripheral blood of six affected individuals and six unaffected family members by using quantitative RT-PCR. The results showed that the abundance of DHTKD1 mRNA in affected persons was less than half of that in unaffected individuals (3.05 ± 1.72 versus 6.92 ± 1.51, p < 0.01) (Figure 3A), suggesting that DHTKD1 mRNA harboring the nonsense mutation might be degraded through nonsense-mediated mRNA decay (NMD). It is well known that the NMD pathway can be triggered by mRNA harboring either a frameshift or a nonsense mutation, and this can lead to the rapid degradation of mutant mRNA and the protection of cells from the production of nonfunctional or truncated proteins with a dominant-negative effect.17Khajavi M. Inoue K. Lupski J.R. Nonsense-mediated mRNA decay modulates clinical outcome of genetic disease.Eur. J. Hum. Genet. 2006; 14: 1074-1081Crossref PubMed Scopus (300) Google Scholar To address whether the insufficient expression of mutant DHTKD1 is due to mRNA degradation via NMD, we transfected wild-type and mutant enhanced-green-fluorescent-protein (EGFP)-DHTKD1 expression vectors at the same dose into human embryonic kidney (HEK) 293T cells. As expected, the cells transfected with the mutant construct revealed much weaker fluorescence signals than did those transfected with the wild-type construct (Figure 3B). Under the same experimental settings, total cell lysates were prepared from transfected cells at different times posttransfection. Immunoblot analysis using antibodies against either DHTKD1 or EGFP showed a smaller, truncated EGFP-fusion product (∼83 kDa) with much lower protein levels in mutant-construct-transfected cells than those in the cells transfected with the wild-type construct, which normally produces the full-length fusion protein (∼130 kDa) (Figure 3C). Accordingly, the mRNA transcribed from the mutant construct was significantly decreased (Figure 3D) and degraded more rapidly than did the mRNA from the wild-type construct after actinomycin D treatment (Figure 3E). To confirm whether mutant mRNA is degraded via NMD, we performed an RNA-silencing experiment in HEK 293T cells; we aimed to suppress the NMD pathway by using specific oligomers against the core NMD factor UPF1 (UPF1 regulator of nonsense transcripts homolog [MIM 601430]).18Mendell J.T. ap Rhys C.M. Dietz H.C. Separable roles for rent1/hUpf1 in altered splicing and decay of nonsense transcripts.Science. 2002; 298: 419-422Crossref PubMed Scopus (224) Google Scholar The results showed that UPF1 was effectively reduced to 1/3–1/2 of the control at both mRNA and protein levels. As expected, decreased mutant mRNA and truncated protein produced by the cotransfected mutant EGFP-DHTKD1 expression vector were rescued with downregulation of UPF1 in a dose-dependent manner (Figures 3F and 3G). Thus, we demonstrated that DHTKD1 mRNA harboring the premature-translational-termination-codon mutation is degraded through the NMD pathway and thus leads to a considerably lower protein level of the truncated protein. DHTKD1 was expressed ubiquitously in various tissues and was proposed to localize to the mitochondria. Previously, a structure-function analysis showed that DHTKD1 probably catalyzes transformation of a physiologically relevant structural analog of 2-oxoglutarate.15Bunik V.I. Degtyarev D. Structure-function relationships in the 2-oxo acid dehydrogenase family: substrate-specific signatures and functional predictions for the 2-oxoglutarate dehydrogenase-like proteins.Proteins. 2008; 71: 874-890Crossref PubMed Scopus (63) Google Scholar It is known that 2-oxoglutarate is converted to succinyl-CoA and CO2 in the presence of the 2-oxoglutarate-dehydrogenase complex (also known as the alpha-ketoglutarate dehydrogenase complex), which is composed of 2-oxoglutarate dehydrogenase (OGDH, E1 [MIM 613022]), dihydrolipoamide succinyltransferase (DLST, E2 [MIM 126063]), and lipoamide dehydrogenase (DLDH, E3 [MIM 238331]).19Gibson G.E. Park L.C. Sheu K.F. Blass J.P. Calingasan N.Y. The α-ketoglutarate dehydrogenase complex in neurodegeneration.Neurochem. Int. 2000; 36: 97-112Crossref PubMed Scopus (177) Google Scholar DHTKD1 and OGDHL, oxoglutarate-dehydrogenase-like, were presumed to be similar to 2-oxoglutarate dehydrogenase (EC 1.1.4.2).15Bunik V.I. Degtyarev D. Structure-function relationships in the 2-oxo acid dehydrogenase family: substrate-specific signatures and functional predictions for the 2-oxoglutarate dehydrogenase-like proteins.Proteins. 2008; 71: 874-890Crossref PubMed Scopus (63) Google Scholar Thus, it is reasonable to postulate that DHTKD1 functions as a 2-oxoglutarate-dehydrogenase E1 component and plays an important role in energy production in mitochondria through the tricarboxylic-acid cycle. To address whether DHTKD1 plays a role in energy production in mitochondria, we checked the cellular localization of endogenous DHTKD1 stained with a specific antibody in the HepG2 cell line. MitoTracker-Red dye was used as a mitochondrial probe. As expected, endogenous DHTKD1 showed typically cytoplamic localization and colocalized with mitochondria (Figure S3). We then designed three siRNA oligomers against DHTKD1. The HEK 293T cells transfected with these three oligomers showed an effective silencing of endogenous DHTKD1 at both mRNA and protein expression levels (Figure S4). Finally, we performed an NAD+/NADH colorimetric assay for the energy transformation and redox state in HEK 293T cells,20Dannelly H.K. Roseman S. NAD+ and NADH regulate an ATP-dependent kinase that phosphorylates enzyme I of the Escherichia coli phosphotransferase system.Proc. Natl. Acad. Sci. USA. 1992; 89: 11274-11276Crossref PubMed Scopus (10) Google Scholar in which DHTKD1 was effectively silenced with a DHTKD1 siRNA mixture containing a molecular ratio equivalent to that of three DHTKD1 siRNAs (Figures 4A and 4B ). It was found that the levels of ATP (Figure 4C), total NAD+ and NADH (Figure 4D), and NADH (Figure 4E) were significantly decreased and accordingly increased the ratio of NAD+/NADH (Figure 4F) in DHTKD1-insufficient cells compared to controls (p < 0.05). These data indicate that DHTKD1 is essential for energy production. In vitro deprivation of DHTKD1 via RNA interference led to reduced production of ATP, total NAD+ and NADH, and NADH, suggesting an essential role for DHTKD1 in normal mitochondrial function and energy production. Mitochondrial dysfunction is known to be involved in various neurodegenerative diseases, including CMT2. Several CMT2-associated genes, including MFN2 (MIM 608507) and GDAP1 (MIM 606598), have been identified as nuclear-DNA-encoded mitochondrial proteins.8Züchner S. Vance J.M. Molecular genetics of autosomal-dominant axonal Charcot-Marie-Tooth disease.Neuromolecular Med. 2006; 8: 63-74Crossref PubMed Scopus (67) Google Scholar Mutations in MFN2 (Mitofusin 2) have been shown to lead to the dispersal of mitochondria and reduced mitochondrial mobility. The downregulation of MFN2 could decrease glucose oxidation and reduce mitochondrial-membrane potential and then lead to insufficient axonal transport of mitochondria, presumably in the extended axons of peripheral nerves.21Santel A. Fuller M.T. Control of mitochondrial morphology by a human mitofusin.J. Cell Sci. 2001; 114: 867-874Crossref PubMed Google Scholar, 22Pich S. Bach D. Briones P. Liesa M. Camps M. Testar X. Palacín M. Zorzano A. The Charcot-Marie-Tooth type 2A gene product, Mfn2, up-regulates fuel oxidation through expression of OXPHOS system.Hum. Mol. Genet. 2005; 14: 1405-1415Crossref PubMed Scopus (338) Google Scholar Ganglioside-induced differentiation-associated protein 1 (GDAP1) encodes a protein anchored to the mitochondrial outer membrane. Mutations in GDAP1 were found to result in CMT disease type 2K (CMT2K [MIM 607831]) or CMT disease type 4A (MIM 214400). Interestingly enough, GDAP1 mutations in fibroblasts from CMT2K-affected persons harboring a c.719G>A (p.Cys240Tyr) mutation (RefSeq NM_018972.2) are associated with a mitochondrial-complex-I defect.23Cassereau J. Chevrollier A. Gueguen N. Malinge M.C. Letournel F. Nicolas G. Richard L. Ferre M. Verny C. Dubas F. et al.Mitochondrial complex I deficiency in GDAP1-related autosomal dominant Charcot-Marie-Tooth disease (CMT2K).Neurogenetics. 2009; 10: 145-150Crossref PubMed Scopus (68) Google Scholar Complex I deficiency leads to reduced NADH oxidation and decreased electron transfer, causing a sharp reduction in ATP synthesis. The lack of ATP could reduce mitochondrial mobility, particularly in the distal portions of neuronal axons.23Cassereau J. Chevrollier A. Gueguen N. Malinge M.C. Letournel F. Nicolas G. Richard L. Ferre M. Verny C. Dubas F. et al.Mitochondrial complex I deficiency in GDAP1-related autosomal dominant Charcot-Marie-Tooth disease (CMT2K).Neurogenetics. 2009; 10: 145-150Crossref PubMed Scopus (68) Google Scholar Insufficient mitochondrial motility in the long axons might explain, at least in part, why the distal portions of the peripheral nerves are principally affected in CMT disease involving GDAP1 mutations.12Cassereau J. Chevrollier A. Gueguen N. Desquiret V. Verny C. Nicolas G. Dubas F. Amati-Bonneau P. Reynier P. Bonneau D. Procaccio V. Mitochondrial dysfunction and pathophysiology of Charcot-Marie-Tooth disease involving GDAP1 mutations.Exp. Neurol. 2011; 227: 31-41Crossref PubMed Scopus (73) Google Scholar Similar to the mutations in MFN2 and GDAP1, the DHTKD1 nonsense mutation identified in this pedigree leads to insufficient energy production and dysfunction of peripheral nerves as a result of rapid mRNA degradation via NMD. In conclusion, our findings demonstrate that CMT2 can be caused by the nonsense mutation in DHTKD1, implicating an essential role for DHTKD1 in energy production, normal neurological function, and the normal redox reaction in mitochondria. We thank all members of the Charcot-Marie-Tooth-affected family for their selfless contribution to scientific discovery. We thank Professor Jian Zhang, Hui-zhen Zhang, and Hua-cheng Wu for technical assistance. This work is partially supported by grants from the Chinese National Science Fund for Distinguished Young Scholars (39925023 to Z.-g.W. and 30625019 to W.H.), the National Natural Science Foundation of China (31071107 to M.-m.G. and 30530390 to Z.-g.W.), the Ministry of Science and Technology of China (2006BAI23B02 and 2011BAI15B02), the Science and Technology Commission of Shanghai Municipality (06DZ05907, 07DZ22929, 10DZ2251500, and 11DZ2292400), and the E-Institutes of Shanghai Municipal Education Commission (E03003). Download .pdf (.17 MB) Help with pdf files Document S1. Figures S1–S4 and Tables S1–S3 The URLs for data presented herein are as follows:1000 Genomes Project, http://www.1000genomes.org/BLAST, http://www.ncbi.nlm.nih.gov/BLAST/GenBank, http://www.ncbi.nlm.nih.gov/Genbank/GeneReviews, Bird, T.D. (2012). Charcot-Marie-Tooth Neuropathy Type 2, http://www.ncbi.nlm.nih.gov/books/NBK1285HUGO Gene Nomenclature Committee, http://www.genenames.org/Human Genome Variation Society, http://www.hgvs.org/mutnomen/Inherited Peripheral Neuropathies Mutation Database, http://www.molgen.ua.ac.be/CMTMutations/NCBI Conserved Domain Database, http://www.ncbi.nlm.nih.gov/Structure/cdd/cdd.shtmlOnline Mendelian Inheritance in Man (OMIM), http://www.omim.org/PyMOL, http://www.pymol.org/ DHTKD1 Mutations Cause 2-Aminoadipic and 2-Oxoadipic AciduriaDanhauser et al.The American Journal of Human GeneticsNovember 8, 2012In BriefAbnormalities in metabolite profiles are valuable indicators of underlying pathologic conditions at the molecular level. However, their interpretation relies on detailed knowledge of the pathways, enzymes, and genes involved. Identification and characterization of their physiological function are therefore crucial for our understanding of human disease: they can provide guidance for therapeutic intervention and help us to identify suitable biomarkers for monitoring associated disorders. We studied two individuals with 2-aminoadipic and 2-oxoadipic aciduria, a metabolic condition that is still unresolved at the molecular level. Full-Text PDF Open Archive
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