A Novel KMT2D Variant with Treatable Secondary Mitochondrial Myopathy in a Lebanese Female with Kabuki Syndrome
SHAIB Mohamad1, ANTOUN Christophe1, MAALOUF George1, FAYYAD Wissam2, SABA Carole1,2, HAGE Pierre1,2, El HACHEM Georges1,3, ABOU KHALIL Bassam1,4, HAMOUCHE Naji1,2, TOHME Rana1,2, MEGARBANE Andre5,6, MANSOUR Hicham1,2*
1Faculty of Medicine, Saint George University of Beirut, Lebanon.
2Department of Pediatrics, Saint George University Medical Center, Beirut, Lebanon.
3Division of Hematology/Oncology, Department of Clinical Medicine, Saint George University Medical Center, Beirut, Lebanon.
4Cardiothoracic surgery division, Saint George University Medical Center, Beirut, Lebanon.
5Department of Human Genetics, Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Lebanon.
6Institut Jerome Lejeune, Paris, France.
*Corresponding Author: MANSOUR Hicham, Faculty of Medicine, Saint George University of Beirut, Lebanon.
https://doi.org/10.58624/SVOAPD.2026.05.003
Received: March 07, 2026
Published: March 24, 2026
Citation: Shaib M, Antoun C, Maalouf G, Fayyad W, Saba C, Hage P, El Hachem G, Abou Khalil B, Hamouche N, Tohme R, Megarbane A, Mansour H. A Novel KMT2D Variant with Treatable Secondary Mitochondrial Myopathy in a Lebanese Female with Kabuki Syndrome. SVOA Paediatrics 2026, 5:2, 14 19. doi: 10.58624/SVOAPD.2026.05.003
Abstract
Kabuki syndrome (KS) is a multisystem disorder primarily caused by mutations in the KMT2D gene. We report here a 20-year-old female with a novel KMT2D variant (c.4690G>A) presenting with multiple autoimmune conditions (Type 1 Diabetes, Graves’ disease, Celiac disease) and a Type B2 Thymoma. Her presenting symptoms were a secondary mitochondrial myopathy with diabetes, with a proximal weakness and elevated lactate blood level. Neuromuscular function showed sustained recovery following mitochondrial support therapy with L-Carnitine and Coenzyme Q10. This case is the first reported novel KS variant in the Lebanese population, with a secondary mitochondrial myopathy responding to treatment.
Keywords: Kabuki Syndrome, KMT2D, Polyautoimmunity, Thymoma, Secondary Mitochondrial Myopathy, Myopathy, Type 1 Diabetes, Graves’ Disease, Lactic Acidosis, Lebanese