@article {690,
	title = {Bi-allelic GOT2 Mutations Cause a Treatable Malate-Aspartate Shuttle-Related Encephalopathy.},
	journal = {Am J Hum Genet},
	volume = {105},
	year = {2019},
	month = {2019 Sep 05},
	pages = {534-548},
	abstract = {<p>Early-infantile encephalopathies with epilepsy are devastating conditions mandating an accurate diagnosis to guide proper management. Whole-exome sequencing was used to investigate the disease etiology in four children from independent families with intellectual disability and epilepsy, revealing bi-allelic GOT2 mutations. In-depth metabolic studies in individual 1 showed low plasma serine, hypercitrullinemia, hyperlactatemia, and hyperammonemia. The epilepsy was serine and pyridoxine responsive. Functional consequences of observed mutations were tested by measuring enzyme activity and by cell and animal models. Zebrafish and mouse models were used to validate brain developmental and functional defects and to test therapeutic strategies. GOT2 encodes the mitochondrial glutamate oxaloacetate transaminase. GOT2 enzyme activity was deficient in fibroblasts with bi-allelic mutations. GOT2, a member of the malate-aspartate shuttle, plays an essential role in the intracellular NAD(H) redox balance. De novo serine biosynthesis was impaired in fibroblasts with GOT2 mutations and GOT2-knockout HEK293 cells. Correcting the highly oxidized cytosolic NAD-redox state by pyruvate~supplementation restored serine biosynthesis in GOT2-deficient cells. Knockdown of got2a in zebrafish resulted in a brain developmental defect associated with seizure-like electroencephalography spikes, which could be rescued by supplying pyridoxine in embryo water. Both pyridoxine and serine synergistically rescued embryonic developmental defects in zebrafish got2a morphants. The two treated individuals reacted favorably to their treatment. Our data provide a mechanistic basis for the biochemical abnormalities in GOT2 deficiency that may also hold for other MAS defects.</p>},
	issn = {1537-6605},
	doi = {10.1016/j.ajhg.2019.07.015},
	author = {van Karnebeek, Clara D M and Ramos, R{\'u}ben J and Wen, Xiao-Yan and Tarailo-Graovac, Maja and Gleeson, Joseph G and Skrypnyk, Cristina and Brand-Arzamendi, Koroboshka and Karbassi, Farhad and Issa, Mahmoud Y and van der Lee, Robin and Dr{\"o}gem{\"o}ller, Britt I and Koster, Janet and Rousseau, Justine and Campeau, Philippe M and Wang, Youdong and Cao, Feng and Li, Meng and Ruiter, Jos and Ciapaite, Jolita and Kluijtmans, Leo A J and Willemsen, Michel A A P and Jans, Judith J and Ross, Colin J and Wintjes, Liesbeth T and Rodenburg, Richard J and Huigen, Marleen C D G and Jia, Zhengping and Waterham, Hans R and Wasserman, Wyeth W and Wanders, Ronald J A and Verhoeven-Duif, Nanda M and Zaki, Maha S and Wevers, Ron A}
}
@article {99,
	title = {Biallelic Mutations in UNC80 Cause Persistent Hypotonia, Encephalopathy, Growth Retardation, and Severe Intellectual Disability.},
	journal = {Am J Hum Genet},
	volume = {98},
	year = {2016},
	month = {2016 Jan 07},
	pages = {202-9},
	abstract = {<p>Ion channel proteins are required for both the establishment of resting membrane potentials and the generation of action potentials. Hundreds of mutations in genes encoding voltage-gated ion channels responsible for action potential generation have been found to cause severe neurological diseases. In contrast, the roles of voltage-independent "leak" channels, important for the establishment and maintenance of resting membrane potentials upon which action potentials are generated, are not well established in human disease. UNC80 is a large component of the NALCN sodium-leak channel complex that regulates the basal excitability of the nervous system. Loss-of-function mutations of NALCN cause infantile hypotonia with psychomotor retardation and characteristic facies (IHPRF). We report four individuals from three unrelated families who have homozygous missense or compound heterozygous truncating mutations in UNC80 and persistent hypotonia, encephalopathy, growth failure, and severe intellectual disability. Compared to control cells, HEK293T cells transfected with an expression plasmid containing the c.5098C>T (p.Pro1700Ser) UNC80 mutation found in one individual showed markedly decreased NALCN channel currents. Our findings demonstrate the fundamental significance of UNC80 and basal ionic conductance to human health. </p>},
	keywords = {Adolescent, Alleles, Brain Diseases, Carrier Proteins, Child, Child, Preschool, Female, Growth Disorders, Humans, Intellectual Disability, Membrane Proteins, Muscle Hypotonia, Mutation, Severity of Illness Index},
	issn = {1537-6605},
	doi = {10.1016/j.ajhg.2015.11.004},
	author = {Stray-Pedersen, Asbj{\o}rg and Cobben, Jan-Maarten and Prescott, Trine E and Lee, Sora and Cang, Chunlei and Aranda, Kimberly and Ahmed, Sohnee and Alders, Marielle and Gerstner, Thorsten and Aslaksen, Kathinka and T{\'e}treault, Martine and Qin, Wen and Hartley, Taila and Jhangiani, Shalini N and Muzny, Donna M and Tarailo-Graovac, Maja and van Karnebeek, Clara D M and Lupski, James R and Ren, Dejian and Yoon, Grace}
}
