title: Thiamine responsive megaloblastic anemia syndrome: a novel homozygous SLC19A2 gene mutation identified.
abstract: Thiamine responsive megaloblastic anemia syndrome (TRMAS) is a rare autosomal recessive disorder especially in countries where consanguinity is uncommon. Three main features are characteristic of the disease - megaloblastic anemia, early onset deafness, and non-type I diabetes. TRMAS is a Mendelian disorder; a gene SLC19A2 coding high affinity thiamine transporter mediating vitamin B1 uptake through cell membrane has been identified. We present the first patient with TRMAS in Lithuania - a 3-year-old boy born to a non-consanguineous family with a novel homozygous SLC19A2 gene mutation. The patient had insulin dependent diabetes (onset 11 months), respiratory illness (onset 11 months), bilateral profound hearing loss (onset at 7 months, verified at 20 months), refractory anemia (onset 2 years), and decreased vision acuity and photophobia (onset 2.5 years). The psychomotor abilities developed according to age. Phenotypic evaluation did not reveal any dysmorphic features. The clinical diagnosis of TRMAS was suspected and daily supplementation with thiamine 100 mg was started. The condition of the patient markedly improved several days after the initiation of treatment. The results of SLC19A2 gene molecular testing confirmed the clinical diagnosis - novel homozygous c.[205G>T], p.[(Val69Phe)] mutation changing conserved amino acid residue or even interfering the mRNA splicing. Clinical heterogeneity, diverse dynamics, and wide spectrum of symptoms are aggravating factors in the diagnosis. The possibility of treatment demands early recognition of disorder to facilitate the improvement of the patient's condition.
authors.affiliation: Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
authors.forename: Violeta
authors.initials: V
authors.lastname: Mikstiene
authors.affiliation: Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
authors.forename: Jurgita
authors.initials: J
authors.lastname: Songailiene
authors.affiliation: Centre of Ear, Nose and Throat Diseases, Vilnius University Hospital Santariškių Clinics, Vilnius, Lithuania.
authors.forename: Jekaterina
authors.initials: J
authors.lastname: Byckova
authors.affiliation: Pediatric Oncology and Hematology Unit, Hospital of Lithuanian university of Health Sciences, Kaunas Clinics, Kaunas, Lithuania.
authors.forename: Giedre
authors.initials: G
authors.lastname: Rutkauskiene
authors.affiliation: Department of Endocrinology, Hospital of Lithuanian University of Health Science, Kaunas Clinics, Kaunas, Lithuania.
authors.forename: Edita
authors.initials: E
authors.lastname: Jasinskiene
authors.affiliation: Department of Endocrinology, Hospital of Lithuanian University of Health Science, Kaunas Clinics, Kaunas, Lithuania.
authors.forename: Rasa
authors.initials: R
authors.lastname: Verkauskiene
authors.affiliation: Centre of Ear, Nose and Throat Diseases, Vilnius University Hospital Santariškių Clinics, Vilnius, Lithuania.
authors.forename: Eugenijus
authors.initials: E
authors.lastname: Lesinskas
authors.affiliation: Department of Human and Medical Genetics, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
authors.forename: Algirdas
authors.initials: A
authors.lastname: Utkus
mesh_terms: D000749:Anemia, Megaloblastic / Q000188:drug therapy* / Q000235:genetics*; D001483:Base Sequence; D002675:Child, Preschool; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000235:genetics*; D006319:Hearing Loss, Sensorineural / Q000188:drug therapy* / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D008097:Lithuania; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013831:Thiamine / Q000627:therapeutic use*; D013832:Thiamine Deficiency / Q000151:congenital* / Q000188:drug therapy / Q000235:genetics; D016896:Treatment Outcome
chemical_list: D026901:Membrane Transport Proteins; C120043:SLC19A2 protein, human; D013831:Thiamine
keywords: SLC19A2 gene mutations; deafness; non-type 1 diabetes; thiamine responsive megaloblastic anemia syndrome (TRMAS); thiamine transporter THTR1