diagnostics Article Mutational Analysis and mtDNA Haplogroup Characterization in Three Serbian Cases of Mitochondrial Encephalomyopathies and Literature Review Phepy G. A. Dawod 1,2 , Jasna Jancic 1,3 , Ana Marjanovic 1 , Marija Brankovic 1 , Milena Jankovic 4 , Janko Samardzic 5 , Ayman Gamil Anwar Dawod 6 , Ivana Novakovic 1 , Fayda I. Abdel Motaleb 2 , Vladimir Radlovic 1,7 , Vladimir S. Kostic 1,4 and Dejan Nikolic 1,8, *   Citation: Dawod, P.G.A.; Jancic, J.; Marjanovic, A.; Brankovic, M.; Jankovic, M.; Samardzic, J.; Gamil Anwar Dawod, A.; Novakovic, I.; Abdel Motaleb, F.I.; Radlovic, V.; et al. Mutational Analysis and mtDNA Haplogroup Characterization in Three Serbian Cases of Mitochondrial Encephalomyopathies and Literature Review. Diagnostics 2021, 11, 1969. https://doi.org/10.3390/ diagnostics11111969 Academic Editor: Ivana Kholová Received: 5 September 2021 Accepted: 21 October 2021 Published: 23 October 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; fibygamilanwer@med.asu.edu.eg (P.G.A.D.); jasna.jancic.npk@gmail.com (J.J.); ana.marjanovic@yahoo.com (A.M.); mara.brankovic@gmail.com (M.B.); ivana.novakovic@med.bg.ac.rs (I.N.); vladimir.radlovic@gmail.com (V.R.); vladimir.s.kostic@gmail.com (V.S.K.) 2 Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Ain Shams University, Cairo 11591, Egypt; dr.fayda@hotmail.com 3 Clinic of Neurology and Psychiatry of Children and Youth, 11000 Belgrade, Serbia 4 Neurology Clinic, Clinical Center of Serbia, 11000 Belgrade, Serbia; milena.jankovic.82@gmail.com 5 Institute of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; jankomedico@yahoo.es 6 Internal Medicine, Hepatogastroenterology and Endoscopy Department, Faculty of Medicine, Ain Shams University, Cairo 11591, Egypt; ayman.gamil@med.asu.edu.eg 7 Pediatric Surgery Department, University Children’s Hospital, 11000 Belgrade, Serbia 8 Physical Medicine and Rehabilitation Department, University Children’s Hospital, Tirsova 10, 11000 Belgrade, Serbia * Correspondence: denikol27@gmail.com Abstract: Mitochondrial encephalomyopathies (MEMP) are heterogeneous multisystem disorders frequently associated with mitochondrial DNA (mtDNA) mutations. Clinical presentation varies considerably in age of onset, course, and severity up to death in early childhood. In this study, we performed molecular genetic analysis for mtDNA pathogenic mutation detection in Serbian children, preliminary diagnosed clinically, biochemically and by brain imaging for mitochondrial encephalomyopathies disorders. Sanger sequencing analysis in three Serbian probands revealed two known pathogenic mutations. Two probands had a heteroplasmic point mutation m.3243A>G in the MT-TL1 gene, which confirmed mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke- like episode syndrome (MELAS), while a single case clinically manifested for Leigh syndrome had an almost homoplasmic (close to 100%) m.8993T>G mutation in the MT-ATP6 gene. After full mtDNA MITOMASTER analysis and PhyloTree build 17, we report MELAS’ association with haplogroups U and H (U2e and H15 subclades); likewise, the mtDNA-associated Leigh syndrome proband shows a preference for haplogroup H (H34 subclade). Based on clinical–genetic correlation, we suggest that haplogroup H may contribute to the mitochondrial encephalomyopathies’ phenotypic variability of the patients in our study. We conclude that genetic studies for the distinctive mitochondrial encephalomyopathies should be well-considered for realizing clinical severity and possible outcomes. Keywords: MELAS; leigh syndrome; mtDNA; sanger sequencing; mutations; haplogroups 1. Introduction Mitochondrial encephalomyopathies (MEMP) are clinically and genetically hetero- geneous group of neurometabolic disorders resulting from abnormal mitochondrial func- tion [1]. They are represented with various clinical syndromes sharing the oxidative phosphorylation deficiency due to alteration in the enzymes essential to the production of ATP in mitochondria. In general, MEMPs are caused by mutations in genes that control Diagnostics 2021, 11, 1969. https://doi.org/10.3390/diagnostics11111969 https://www.mdpi.com/journal/diagnostics