3-methylglutaconic aciduria with deafness, encephalopathy, and Leigh-like syndrome

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Description from OMIM

MEGDEL is an autosomal recessive disorder characterized by childhood onset of delayed psychomotor development or psychomotor regression, sensorineural deafness, spasticity or dystonia, and increased excretion of 3-methylglutaconic acid. Brain imaging shows cerebral and cerebellar atrophy as well as lesions in the basal ganglia reminiscent of Leigh syndrome (256000). Laboratory studies show increased serum lactate and alanine, mitochondrial oxidative phosphorylation defects, abnormal mitochondria, abnormal phosphatidylglycerol and cardiolipin profiles in fibroblasts, and abnormal accumulation of unesterified cholesterol within cells (summary by Wortmann et al., 2012). About 50% of patients develop severe, but transient, liver dysfunction and/or signs of liver failure, in the neonatal period or during the first year of life, prompting some authors to suggest the name 'MEGDHEL' syndrome, with the 'H' referring to 'hepatopathy' (summary by Maas et al., 2017). Some patients may have a milder presentation with juvenile-onset spasticity and mild cognitive impairment, indicating a broader phenotypic spectrum (Roeben et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of 3-methylglutaconic aciduria, see MGCA type I (250950).

Prevalence of clinical parameters (%)

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List of symptoms

Symptom/sign Organ system Percent affected Pubmed id Added on(yyyy-mm-dd) Edit/add reference
Psychomotor retardation nervous 100 % 22683713 2013-11-14
Spasticity nervous 100 % 22683713 2013-11-14
Dystonia nervous 100 % 22683713 2013-11-14
Hearing loss nervous 100 % 22683713 2013-11-14
Developmental delay nervous 100 % 22683713 2013-11-14
Cerebellar atrophy nervous 100 % 22683713 2013-11-14
Cerebral atrophy nervous 100 % 22683713 2013-11-14
Basal ganglia pathology nervous 100 % 22683713 2013-11-14
3-methylglutaconic aciduria urinary 100 % 22683713 2013-11-14
Lactate accumulation circulatory 93 % 22683713 2013-11-14
Increased serum alanine circulatory 62 % 22683713 2013-11-14

List of references:

Mutations in the phospholipid remodeling gene SERAC1 impair mitochondrial function and intracellular cholesterol trafficking and cause dystonia and deafness.
Saskia B Wortmann, Frédéric M Vaz, Thatjana Gardeitchik, Lisenka E L M Vissers, G Herma Renkema, Janneke H M Schuurs-Hoeijmakers, Wim Kulik, Martin Lammens, Christin Christin, Leo A J Kluijtmans, Richard J Rodenburg, Leo G J Nijtmans, Anne Grünewald, Christine Klein, Joachim M Gerhold, Tamas Kozicz, Peter M van Hasselt, Magdalena Harakalova, Wigard Kloosterman, Ivo Barić, Ewa Pronicka, Sema Kalkan Ucar, Karin Naess, Kapil K Singhal, Zita Krumina, Christian Gilissen, Hans van Bokhoven, Joris A Veltman, Jan A M Smeitink, Dirk J Lefeber, Johannes N Spelbrink, Ron A Wevers, Eva Morava, Arjan P M de Brouwer,

Using exome sequencing, we identify SERAC1 mutations as the cause of MEGDEL syndrome, a recessive disorder of dystonia and deafness with Leigh-like syndrome, impaired oxidative phosphorylation and 3-methylglutaconic aciduria. We localized SERAC1 at the interface between the mitochondria and the endoplasmic reticulum in the mitochondria-associated membrane fraction that is essential for phospholipid exchange. A phospholipid analysis in patient fibroblasts showed elevated concentrations of phosphatidylglycerol-34:1 (where the species nomenclature denotes the number of carbon atoms in the two acyl chains:number of double bonds in the two acyl groups) and decreased concentrations of phosphatidylglycerol-36:1 species, resulting in an altered cardiolipin subspecies composition. We also detected low concentrations of bis(monoacyl-glycerol)-phosphate, leading to the accumulation of free cholesterol, as shown by abnormal filipin staining. Complementation of patient fibroblasts with wild-type human SERAC1 by lentiviral infection led to a decrease and partial normalization of the mean ratio of phosphatidylglycerol-34:1 to phosphatidylglycerol-36:1. Our data identify SERAC1 as a key player in the phosphatidylglycerol remodeling that is essential for both mitochondrial function and intracellular cholesterol trafficking.

Nature genetics - Jun 2012