Ken Saida, Reza Maroofian, Toru Sengoku, Tadahiro Mitani, Alistair T. Pagnamenta, Dana Marafi, Maha S. Zaki, Thomas J. O’Brien, Ehsan Ghayoor Karimiani, Rauan Kaiyrzhanov, Marina Takizawa, Sachiko Ohori, Huey Yin Leong, Gulsen Akay, Hamid Galehdari, Mina Zamani, Ratna Romy, Christopher J. Carroll, Mehran Beiraghi Toosi, Farah Ashrafzadeh, Shima Imannezhad, Hadis Malek, Najmeh Ahangari, Hoda Tomoum, Vykuntaraju K. Gowda, Varunvenkat M. Srinivasan, David Murphy, Natalia Dominik, Hasnaa M. Elbendary, Karima Rafat, Sanem Yilmaz, Seda Kanmaz, Mine Serin, Deepa Krishnakumar, Alice Gardham, Anna Maw, Tekki Sreenivasa Rao, Sarah Alsubhi, Myriam Srour, Daniela Buhas, Tamison Jewett, Rachel E. Goldberg, Hanan Shamseldin, Eirik Frengen, Doriana Misceo, Petter Strømme, José Ricardo Magliocco Ceroni, Chong Ae Kim, Gozde Yesil, Esma Sengenc, Serhat Guler, Mariam Hull, Mered Parnes, Dilek Aktas, Banu Anlar, Yavuz Bayram, Davut Pehlivan, Jennifer E. Posey, Shahryar Alavi, Seyed Ali Madani Manshadi, Hamad Alzaidan, Mohammad Al-Owain, Lama Alabdi, Ferdous Abdulwahab, Futoshi Sekiguchi, Kohei Hamanaka, Atsushi Fujita, Yuri Uchiyama, Takeshi Mizuguchi, Satoko Miyatake, Noriko Miyake, Reem M. Elshafie, Kamran Salayev, Ulviyya Guliyeva, Fowzan S. Alkuraya, Joseph G. Gleeson, Kristin G. Monaghan, Katherine G. Langley, Hui Yang, Mahsa Motavaf, Saeid Safari, Mozhgan Alipour, Kazuhiro Ogata, André E.X. Brown, James R. Lupski, Henry Houlden, and Naomichi Matsumoto
Purpose: Brain monoamine vesicular transport disease is an infantile-onset movement disorder that mimics cerebral palsy. In 2013, the homozygous SLC18A2 variant, p.Pro387Leu, was first reported as a cause of this rare disorder, and dopamine agonists were efficient for treating affected individuals from a single large family. To date, only 6 variants have been reported. In this study, we evaluated genotype–phenotype correlations in individuals with biallelic SLC18A2 variants. Methods: A total of 42 affected individuals with homozygous SLC18A2 variant alleles were identified. We evaluated genotype–phenotype correlations and the missense variants in the affected individuals based on the structural modeling of rat VMAT2 encoded by Slc18a2, with cytoplasm- and lumen-facing conformations. A Caenorhabditis elegans model was created for functional studies. Results: A total of 19 homozygous SLC18A2 variants, including 3 recurrent variants, were identified using exome sequencing. The affected individuals typically showed global developmental delay, hypotonia, dystonia, oculogyric crisis, and autonomic nervous system involvement (temperature dysregulation/sweating, hypersalivation, and gastrointestinal dysmotility). Among the 58 affected individuals described to date, 16 (28%) died before the age of 13 years. Of the 17 patients with p.Pro237His, 9 died, whereas all 14 patients with p.Pro387Leu survived. Although a dopamine agonist mildly improved the disease symptoms in 18 of 21 patients (86%), some affected individuals with p.Ile43Phe and p.Pro387Leu showed milder phenotypes and presented prolonged survival even without treatment. The C. elegans model showed behavioral abnormalities. Conclusion: These data expand the phenotypic and genotypic spectra of SLC18A2-related disorders. © 2022 American College of Medical Genetics and Genomics, National Institutes of Health, NIH: T32 GM007526-42; National Heart, Lung, and Blood Institute, NHLBI; National Human Genome Research Institute, NHGRI: K08 HG008986; National Institute of Neurological Disorders and Stroke, NINDS: R35NS105078; International Rett Syndrome Foundation, IRSF: 3701-1; Muscular Dystrophy Association, MDA: 512848; American Brain Foundation, ABF; American Academy of Neurology, AAN; Takeda Science Foundation, TSF; Japan Agency for Medical Research and Development, AMED: JP22ek0109486, JP22ek0109493, JP22ek0109549; Horizon 2020 Framework Programme, H2020; Muscular Dystrophy UK, MDUK; Multiple System Atrophy Trust, MSAT; Brain Research UK, BRUK; Baylor-Hopkins Center for Mendelian Genomics, BHCMG: UM1 HG006542; Medical Research Council, MRC: G0601943, MR/S005021/1, MR/S01165X/1; Ataxia UK; European Research Council, ERC; Rosetrees Trust; Great Ormond Street Hospital Charity, GOSH; Japan Society for the Promotion of Science, KAKEN: JP19H03621, JP20K07907, JP20K08164, JP20K16932, JP20K17936, JP21k15907; Horizon 2020: 714853, MC-A658-5TY30; University College London Hospitals Biomedical Research Centre, UCLH BRC; King Salman Center for Disability Research, KSCDR: RG-2022-010, We thank the participants and their families for their involvement in this study. This work was supported by the Japan Agency for Medical Research and Development ( AMED ) under grant numbers JP22ek0109486, JP22ek0109549, and JP22ek0109493 (N.Ma.); Japan Society for the Promotion of Science ( JSPS) KAKENHI under grant numbers JP19H03621 (N.Mi.), JP20K07907 (S.M.), JP20K08164 (T.Miz.), JP20K17936 (A.F.), JP20K16932 (K.H.), and JP21k15907 (Y.U.); and the Takeda Science Foundation (T.Miz., N.Mi., and N.Ma.). This study was partially supported by the US National Human Genome Research Institute and National Heart Lung and Blood Institute to the Baylor-Hopkins Center for Mendelian Genomics (UM1 HG006542 to J.R.L.), US National Institute of Neurological Disorders and Stroke (R35NS105078 to J.R.L.), and Muscular Dystrophy Association (512848 to J.R.L.). D.Ma. was supported by a Medical Genetics Research Fellowship Program through the National Institutes of Health (T32 GM007526-42). D.P. was supported by a Clinical Research Training Scholarship in Neuromuscular Disease partnered by the American Academy of Neurology , American Brain Foundation , and Muscle Study Group and by the International Rett Syndrome Foundation (grant number #3701-1). J.E.P. was supported by the National Human Genome Research Institute (K08 HG008986). H.H. was funded by the Medical Research Council ( MRC) (MR/S01165X/1, MR/S005021/1, and G0601943), NIHR University College London Hospitals Biomedical Research Centre , Rosetree Trust, Ataxia UK , Multiple System Atrophy Trust , Brain Research UK , Sparks Great Ormond Street Hospital Charity , Muscular Dystrophy UK , and Muscular Dystrophy Association . N.D. was supported by an MRC strategic award to establish International Centre for Genomic Medicine in Neuromuscular Diseases (MR/S005021/1). This project also received funding from the European Research Council under the European Union’s Horizon 2020 Research and Innovation Program (grant agreement number 714853) and was supported by the Medical Research Council through grant MC-A658-5TY30. We acknowledge the support of King Salman Center for Disability Research through Research Group no RG-2022-010 (F.S.A.). Figure 1A, 2A, and Graphical Abstract were created with BioRender.com ., We thank the participants and their families for their involvement in this study. This work was supported by the Japan Agency for Medical Research and Development (AMED) under grant numbers JP22ek0109486, JP22ek0109549, and JP22ek0109493 (N.Ma.); Japan Society for the Promotion of Science (JSPS) KAKENHI under grant numbers JP19H03621 (N.Mi.), JP20K07907 (S.M.), JP20K08164 (T.Miz.), JP20K17936 (A.F.), JP20K16932 (K.H.), and JP21k15907 (Y.U.); and the Takeda Science Foundation (T.Miz., N.Mi., and N.Ma.). This study was partially supported by the US National Human Genome Research Institute and National Heart Lung and Blood Institute to the Baylor-Hopkins Center for Mendelian Genomics (UM1 HG006542 to J.R.L.), US National Institute of Neurological Disorders and Stroke (R35NS105078 to J.R.L.), and Muscular Dystrophy Association (512848 to J.R.L.). D.Ma. was supported by a Medical Genetics Research Fellowship Program through the National Institutes of Health (T32 GM007526-42). D.P. was supported by a Clinical Research Training Scholarship in Neuromuscular Disease partnered by the American Academy of Neurology, American Brain Foundation, and Muscle Study Group and by the International Rett Syndrome Foundation (grant number #3701-1). J.E.P. was supported by the National Human Genome Research Institute (K08 HG008986). H.H. was funded by the Medical Research Council (MRC) (MR/S01165X/1, MR/S005021/1, and G0601943), NIHR University College London Hospitals Biomedical Research Centre, Rosetree Trust, Ataxia UK, Multiple System Atrophy Trust, Brain Research UK, Sparks Great Ormond Street Hospital Charity, Muscular Dystrophy UK, and Muscular Dystrophy Association. N.D. was supported by an MRC strategic award to establish International Centre for Genomic Medicine in Neuromuscular Diseases (MR/S005021/1). This project also received funding from the European Research Council under the European Union's Horizon 2020 Research and Innovation Program (grant agreement number 714853) and was supported by the Medical Research Council through grant MC-A658-5TY30. We acknowledge the support of King Salman Center for Disability Research through Research Group no RG-2022-010 (F.S.A.). Figure 1A, 2A, and Graphical Abstract were created with BioRender.com.