Browsing by Author "Dionisi-Vici, Carlo"
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- Bi-allelic LETM1 variants perturb mitochondrial ion homeostasis leading to a clinical spectrum with predominant nervous system involvementPublication . Kaiyrzhanov, Rauan; Mohammed, Sami E.M.; Maroofian, Reza; Husain, Ralf A.; Catania, Alessia; Torraco, Alessandra; Alahmad, Ahmad; Dutra-Clarke, Marina; Grønborg, Sabine; Sudarsanam, Annapurna; Vogt, Julie; Arrigoni, Filippo; Baptista, Julia; Haider, Shahzad; Feichtinger, René G.; Bernardi, Paolo; Zulian, Alessandra; Gusic, Mirjana; Efthymiou, Stephanie; Bai, Renkui; Bibi, Farah; Horga, Alejandro; Martinez-Agosto, Julian A.; Lam, Amanda; Manole, Andreea; Rodriguez, Diego-Perez; Durigon, Romina; Pyle, Angela; Albash, Buthaina; Dionisi-Vici, Carlo; Murphy, David; Martinelli, Diego; Bugiardini, Enrico; Allis, Katrina; Lamperti, Costanza; Reipert, Siegfried; Risom, Lotte; Laugwitz, Lucia; Di Nottia, Michela; McFarland, Robert; Vilarinho, Laura; Hanna, Michael; Prokisch, Holger; Mayr, Johannes A.; Bertini, Enrico Silvio; Ghezzi, Daniele; Østergaard, Elsebet; Wortmann, Saskia B.; Carrozzo, Rosalba; Haack, Tobias B.; Taylor, Robert W.; Spinazzola, Antonella; Nowikovsky, Karin; Houlden, HenryLeucine zipper-EF-hand containing transmembrane protein 1 (LETM1) encodes an inner mitochondrial membrane protein with an osmoregulatory function controlling mitochondrial volume and ion homeostasis. The putative association of LETM1 with a human disease was initially suggested in Wolf-Hirschhorn syndrome, a disorder that results from de novo monoallelic deletion of chromosome 4p16.3, a region encompassing LETM1. Utilizing exome sequencing and international gene-matching efforts, we have identified 18 affected individuals from 11 unrelated families harboring ultra-rare bi-allelic missense and loss-of-function LETM1 variants and clinical presentations highly suggestive of mitochondrial disease. These manifested as a spectrum of predominantly infantile-onset (14/18, 78%) and variably progressive neurological, metabolic, and dysmorphic symptoms, plus multiple organ dysfunction associated with neurodegeneration. The common features included respiratory chain complex deficiencies (100%), global developmental delay (94%), optic atrophy (83%), sensorineural hearing loss (78%), and cerebellar ataxia (78%) followed by epilepsy (67%), spasticity (53%), and myopathy (50%). Other features included bilateral cataracts (42%), cardiomyopathy (36%), and diabetes (27%). To better understand the pathogenic mechanism of the identified LETM1 variants, we performed biochemical and morphological studies on mitochondrial K+/H+ exchange activity, proteins, and shape in proband-derived fibroblasts and muscles and in Saccharomyces cerevisiae, which is an important model organism for mitochondrial osmotic regulation. Our results demonstrate that bi-allelic LETM1 variants are associated with defective mitochondrial K+ efflux, swollen mitochondrial matrix structures, and loss of important mitochondrial oxidative phosphorylation protein components, thus highlighting the implication of perturbed mitochondrial osmoregulation caused by LETM1 variants in neurological and mitochondrial pathologies.
- Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiencyPublication . Huemer, Martina; Diodato, Daria; Schwahn, Bernd; Schiff, Manuel; Bandeira, Anabela; Benoist, Jean-Francois; Burlina, Alberto; Cerone, Roberto; Couce, Maria L; Garcia-Cazorla, Angeles; la Marca, Giancarlo; Pasquini, Elisabetta; Vilarinho, Laura; Weisfeld-Adams, James D; Kožich, Viktor; Blom, Henk; Baumgartner, Matthias R; Dionisi-Vici, CarloBackground: Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions. Objective: To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management. Data sources: Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach. Key recommendations: We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early.
- Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiencyPublication . Huemer, Martina; Diodato, Daria; Schwahn, Bernd; Schiff, Manuel; Bandeira, Anabela; Benoist, Jean-Francois; Burlina, Alberto; Cerone, Roberto; Couce, Maria L.; Garcia-Cazorla, Angeles; la Marca, Giancarlo; Pasquini, Elisabetta; Vilarinho, Laura; Weisfeld-Adams, James D.; Kožich, Viktor; Blom, Henk; Baumgartner, Matthias R.; Dionisi-Vici, CarloBackground: Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions. Objective: To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management. Data sources: Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach. Key recommendations: We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early.
- Newborn screening for homocystinurias: recent recommendations versus current practicePublication . Keller, Rebecca; Chrastina, Petr; Pavlíková, Markéta; Gouveia, Sofía; Ribes, Antonia; Kölker, Stefan; Blom, Henk J.; Baumgartner, Matthias R.; Bártl, Josef; Dionisi-Vici, Carlo; Gleich, Florian; Morris, Andrew A.; Kožich, Viktor; Huemer, Martina; Barić, Ivo; Ben-Omran, Tawfeq; Blasco-Alonso, Javier; Bueno Delgado, Maria A.; Carducci, Claudia; Cassanello, Michela; Cerone, Roberto; Couce, Maria Luz; Crushell, Ellen; Delgado Pecellin, Carmen; Dulin, Elena; Espada, Mercedes; Ferino, Giulio; Fingerhut, Ralph; Garcia Jimenez, Immaculada; Gonzalez Gallego, Immaculada; González-Irazabal, Yolanda; Gramer, Gwendolyn; Juan Fita, Maria Jesus; Karg, Eszter; Klein, Jeanette; Konstantopoulou, Vassiliki; la Marca, Giancarlo; Leão Teles, Elisa; Leuzzi, Vincenzo; Lilliu, Franco; Lopez, Rosa Maria; Lund, Allan M.; Mayne, Philip; Meavilla, Silvia; Moat, Stuart J.; Okun, Jürgen G.; Pasquini, Elisabeta; Pedron-Giner, Consuélo Carmen; Racz, Gabor Zoltan; Ruiz Gomez, Maria Angeles; Vilarinho, Laura; Yahyaoui, Raquel; Zerjav Tansek, Moja; Zetterström, Rolf H.; Zeyda, MaximilianPurpose: To assess how the current practice of newborn screening (NBS) for homocystinurias compares with published recommendations. Methods: Twenty-two of 32 NBS programmes from 18 countries screened for at least one form of homocystinuria. Centres provided pseudonymised NBS data from patients with cystathionine beta-synthase deficiency (CBSD, n = 19), methionine adenosyltransferase I/III deficiency (MATI/IIID, n = 28), combined remethylation disorder (cRMD, n = 56) and isolated remethylation disorder (iRMD), including methylenetetrahydrofolate reductase deficiency (MTHFRD) (n = 8). Markers and decision limits were converted to multiples of the median (MoM) to allow comparison between centres. Results: NBS programmes, algorithms and decision limits varied considerably. Only nine centres used the recommended second-tier marker total homocysteine (tHcy). The median decision limits of all centres were ≥ 2.35 for high and ≤ 0.44 MoM for low methionine, ≥ 1.95 for high and ≤ 0.47 MoM for low methionine/phenylalanine, ≥ 2.54 for high propionylcarnitine and ≥ 2.78 MoM for propionylcarnitine/acetylcarnitine. These decision limits alone had a 100%, 100%, 86% and 84% sensitivity for the detection of CBSD, MATI/IIID, iRMD and cRMD, respectively, but failed to detect six individuals with cRMD. To enhance sensitivity and decrease second-tier testing costs, we further adapted these decision limits using the data of 15 000 healthy newborns. Conclusions: Due to the favorable outcome of early treated patients, NBS for homocystinurias is recommended. To improve NBS, decision limits should be revised considering the population median. Relevant markers should be combined; use of the postanalytical tools offered by the CLIR project (Collaborative Laboratory Integrated Reports, which considers, for example, birth weight and gestational age) is recommended. tHcy and methylmalonic acid should be implemented as second-tier markers.