DOOR syndrome: deficiency of E1 component of the 2-oxoglutarate dehydrogenase complex

Functional Assessment of Lipoyltransferase-1 Deficiency in Cells, Mice, and Humans

Inborn errors of metabolism (IEMs) link metabolic defects to human phenotypes. Modern genomics has accelerated IEM discovery, but assessing the impact of genomic variants is still challenging. Here, we integrate genomics and metabolomics to identify a cause of lactic acidosis and epilepsy. The proband is a compound heterozygote for variants in LIPT1, which encodes the lipoyltransferase required for 2-ketoacid dehydrogenase (2KDH) function. Metabolomics reveals abnormalities in lipids, amino acids, and 2-hydroxyglutarate consistent with loss of multiple 2KDHs. Homozygous knockin of a LIPT1 mutation reduces 2KDH lipoylation in utero and results in embryonic demise. In patient fibroblasts, defective 2KDH lipoylation and function are corrected by wild-type, but not mutant, LIPT1 alleles. Isotope tracing reveals that LIPT1 supports lipogenesis and balances oxidative and reductive glutamine metabolism. Altogether, the data extend the role of LIPT1 in metabolic regulation and demonstrate how integrating genomics and metabolomics can uncover broader aspects of IEM pathophysiology.

Dual mode action of mangiferin in mouse liver under high fat diet

Chronic over-nutrition is a major contributor to the spread of obesity and its related metabolic disorders. Development of therapeutics has been slow compared to the speedy increase in occurrence of these metabolic disorders. We have identified a natural compound, mangiferin (MGF) (a predominant component of the plants of Anemarrhena asphodeloides and Mangifera indica), that can protect against high fat diet (HFD) induced obesity, hyperglycemia, insulin resistance and hyperlipidemia in mice. However, the molecular mechanisms whereby MGF exerts these beneficial effects are unknown. To understand MGF mechanisms of action, we performed unbiased quantitative proteomic analysis of protein profiles in liver of mice fed with HFD utilizing 15N metabolically labeled liver proteins as internal standards. We found that out of 865 quantified proteins 87 of them were significantly differentially regulated by MGF. Among those 87 proteins, 50% of them are involved in two major processes, energy metabolism and biosynthesis of metabolites. Further classification indicated that MGF increased proteins important for mitochondrial biogenesis and oxidative activity including oxoglutarate dehydrogenase E1 (Dhtkd1) and cytochrome c oxidase subunit 6B1 (Cox6b1). Conversely, MGF reduced proteins critical for lipogenesis such as fatty acid stearoyl-CoA desaturase 1 (Scd1) and acetyl-CoA carboxylase 1 (Acac1). These mass spectrometry data were confirmed and validated by western blot assays. Together, data indicate that MGF upregulates proteins pivotal for mitochondrial bioenergetics and downregulates proteins controlling de novo lipogenesis. This novel mode of dual pharmacodynamic actions enables MGF to enhance energy expenditure and inhibit lipogenesis, and thereby correct HFD induced liver steatosis and prevent adiposity. This provides a molecular basis supporting development of MGF or its metabolites into therapeutics to treat metabolic disorders.

Proteomic analysis of demyelinated and remyelinating brain tissue following dietary cuprizone administration

Cuprizone intoxication is a commonly used model of demyelination that allows the temporal separation of demyelination and remyelination. The underlying biochemical alterations leading to demyelination, using this model, remain unclear and may be multifold. Analysis of proteomic changes within the brains of cuprizone-exposed animals may help elucidate key cellular processes. In the current study, we report the results of the liquid chromatography tandem mass spectrometry analysis of total protein from the brain hemispheres of control and toxin-exposed mice at 6 weeks of exposure and after 3 and 6 weeks of recovery to identify protein changes during the remyelination phase. We found that at 6 weeks of cuprizone exposure, myelin proteins were reduced compared to controls and increased throughout the course of recovery, as expected. In contrast, other protein groups, such as proteins related to mitochondrial function, were increased at 6 weeks of treatment compared to untreated controls and returned toward control levels following withdrawal of toxin. These results suggest that a global proteomic analysis of the brain tissue of cuprizone-treated mice can identify changes related to the demyelination/remyelination process.

Anaesthetic management of an adult patient with DOOR syndrome: a case report

We report the anaesthetic management of a 48-year-old male patient with Deafness, Onycho-Osteodystrophy and mental Retardation syndrome, epilepsy and cerebral palsy who had two dental procedures under anaesthetic care. For the first short examination sedoanalgesia was employed and the second, longer, procedure was performed under general anaesthesia. His airway management was moderately difficult and the postoperative period was complicated by partial seizures involving the upper extremity and a short period of decreased oxygen saturation. The potential anaesthetic implications of Deafness, Onycho-Osteodystrophy and mental Retardation syndrome are highlighted.

DOOR syndrome concomitant with non-convulsive status epilepticus and hyperintense cerebellar cortex on T2-weighted imaging

We report a case study of an 11-year-old Japanese boy with complex partial status epilepticus, a type of non-convulsive status epilepticus, concomitant with DOOR syndrome. To our knowledge, this is the first report of this type of epilepsy concomitant with DOOR syndrome. Magnetic resonance (MR) imaging showed diffuse atrophy of the cerebellar cortex. The cerebellar cortex was hyperintense on T2-weighted imaging. This finding of MR imaging is rare and has been considered pathognomonic for infantile neuroaxonal dystrophy and Marinesco-Sjogren syndrome which are in the entity of metabolic disease. So this lesion may be the result of a metabolic defect occurring in conjunction with DOOR syndrome.

A new case of DOOR syndrome

We present the case of a 9-year-old boy with DOOR syndrome recognized in the first year of his life because of a delayed development of speech. The diagnosis was based on characteristic abnormalities, including congenital deafness, nail and bone abnormalities, and mild mental retardation.

DOOR syndrome: clinical report, literature review and discussion of natural history

DOOR syndrome (deafness, onychodystrophy, osteodystrophy, and mental retardation) is a rarely described disorder with less than 35 reports in the literature. The hallmarks of the syndrome, represented in the DOOR acronym, include sensorineural hearing loss, hypoplastic or absent nails on the hands and feet, small or absent distal phalanges of the hands and feet, and mental retardation. The purpose of our communication is to report on an additional patient with DOOR syndrome, delineate common as well as less frequent manifestations of DOOR syndrome, bring attention to the under appreciated facial features in DOOR syndrome, document the natural history of this disorder, and propose a suggested workup of those suspected of DOOR syndrome. DOOR syndrome is associated with characteristic, coarse facial features with large nose with wide nasal bridge, bulbous tip and anteverted nares, a long prominent philtrum and downturned corners of the mouth. The natural history is one of a deteriorative course, with progressive neurological manifestations including sensorineural deafness, seizures from infancy, optic atrophy, and a peripheral polyneuropathy. The majority of patients with DOOR syndrome have elevated levels of 2-oxoglutarate in the urine and plasma. In this report, we present a newborn with manifestations consistent with DOOR syndrome and a progressive clinical course. A comprehensive literature review reveals 32 patients with DOOR syndrome. In conclusion, DOOR syndrome is a neurometabolic disorder with recognizable facial features and a progressive natural history.

Severe mental retardation, epilepsy, anal anomalies, and distal phalangeal hypoplasia in siblings

We report two sisters born to consanguineous parents with an identical syndrome consisting of severe mental retardation and epilepsy, hypoplastic terminal phalanges, and anteriorly displaced anus. Further metabolic and genetic testing failed to detect the etiology. A whole genome linkage scan showed homozygosity for a 28-Mb region on chromosome 1p, and a 65-Mb region spanning most of chromosome 14. These results are consistent with an autosomal recessive condition that is similar to, but likely distinct from, Coffin-Siris syndrome.