Thiamine-Responsive Megaloblastic Anaemia With Hypothyroidism, A Puzzling Association.

Background: Thiamine-responsive megaloblastic anaemia (TRMA) is characterized by the classic trio of diabetes mellitus, sensorineural hearing loss, and megaloblastic anaemia, typically emerging subtly between infancy and adolescence. Administration of high-dose thiamine often yields improvements in anaemia and occasionally in diabetes. Uncommon manifestations include optic atrophy, congenital heart defects, short stature, and stroke. In this specific case, a 5-year-old diagnosed with insulin-dependent diabetes mellitus (IDDM) since the age of one presented with symptoms such as polyuria, fever, and vomiting, revealing an HbA1c of 10.64. Further examinations disclosed compromised hearing and vision. A negative antibody workup and a thyroid profile indicating hypothyroidism prompted additional investigations, including Brainstem Evoked Response Audiometry (BERA) and retinal examination, confirming bilateral sensorineural hearing loss and maculopathy, respectively. A comprehensive blood count unveiled megaloblastic anaemia. Genetic profiling confirmed a homozygous mutation in the SLC19A2 gene, thus diagnosing TRMA. An early diagnosis, coupled with genetic confirmation, enables timely intervention, with patients responding positively to high-dose thiamine. Genetic counselling plays a pivotal role in enlightening families about the disease and its inheritance patterns, fostering awareness and understanding.

Leber congenital amaurosis as an initial manifestation in a Chinese patient with thiamine-responsive megaloblastic anemia syndrome.

Thiamine-responsive megaloblastic anemia syndrome (TRMA) is an autosomal recessive disorder, inherited by the defective SLC19A2 gene that encodes a high-affinity thiamine transporter (THTR-1). TRMA is characterized by the occurrence of classical triad manifestations including megaloblastic anemia, diabetes mellitus, and sensorineural deafness. In addition to the systemic manifestations, ophthalmic features can be present and include retinitis pigmentosa, optic atrophy, cone-rod dystrophy, maculopathy, and Leber congenital amaurosis. Here we report a 6-year-old boy presenting severe early-onset retinal dystrophy with the initial diagnosis of Leber congenital amaurosis, which followed for 12 years. Diabetes mellitus occurred 3 years after vision problem. Eosinophilic granuloma of the left scapula was confirmed at 13 years old. Whole-exome sequencing was performed to identify two novel compound heterozygous variants c.725dupC (p.Ala243Serfs*3) and c.121G>A (p.Gly41Ser) in SLC19A2 gene (NM_006996.3). Oral thiamine supplementation treatment was initiated at 13 years. This case demonstrates Leber congenital amaurosis can present as the first clinical feature before systemic manifestations. Phenotypic variety should be aware and multidisciplinary teamwork and regular follow-up are important for TRMA patient care.

The Effects of Genetic Mutations and Drugs on the Activity of the Thiamine Transporter, SLC19A2.

A rare cause of megaloblastic anemia (MA) is thiamine-responsive megaloblastic anemia (TRMA), a genetic disorder caused by mutations in SLC19A2 (encoding THTR1), a thiamine transporter. The study objectives were to (1) functionally characterize selected TRMA-associated SLC19A2 variants and (2) determine whether current prescription drugs associated with drug-induced MA (DIMA) may act via inhibition of SLC19A2. Functional characterization of selected SLC19A2 variants was performed by confocal microscopy and isotopic uptake studies of [3H]-thiamine in HEK293 cells. Sixty-three drugs associated with DIMA were screened for SLC19A2 inhibition in isotopic uptake studies. Three previously uncharacterized SLC19A2 variants identified in TRMA patients exhibited disrupted localization to the plasma membrane along with near-complete loss-of-function. Ten of 63 drugs inhibited SLC19A2-mediated thiamine transport ≥ 50% at screening concentrations; however, with the exception of erythromycin, none was predicted to inhibit SLC19A2 at clinically relevant unbound plasma concentrations. Data from electronic health records revealed reduced levels of thiamine pyrophosphate (TPP) in patients prescribed erythromycin, consistent with inhibition of SLC19A2-mediated thiamine transport. Here, we confirmed the role of three SLC19A2 variants in TRMA pathology. Additionally, we report that inhibition of SLC19A2 is a potential, but uncommon mechanism for DIMA.

Relapse of rare diseases during COVID-19 pandemic: bicytopenia in an adult patient with thiamine-responsive megaloblastic anaemia.

Thiamine-responsive megaloblastic anaemia (TRMA) is a syndrome associated with megaloblastic anaemia, diabetes mellitus and sensorineural deafness, due to mutations in the SLC19A2gene, which codes for a thiamine carrier protein. Oral thiamine supplementation is the main treatment. We report the case of a 19-year-old man known for TRMA, who presented in the emergency department with bicytopenia (haemoglobin 5,4 g/dL, thrombocytes 38×109/L) revealed by dyspnea and chest pain. Investigations excluded bleeding, hemolysis, coagulopathy and iron deficiencies. A recent infection and an acute coronary syndrome have also been eliminated. We later found out that thiamine treatment had been discontinued three months before, due to general confinement in Tunisia during the COVID-19 pandemic. Parenteral administration of 100 mg of thiamine daily resulted in the recovery of haematopoiesis within three weeks.

TRMA syndrome with a severe phenotype, cerebral infarction, and novel compound heterozygous SLC19A2 mutation: a case report.

BACKGROUND: Thiamine-responsive megaloblastic anemia (TRMA) is a rare autosomal recessive inherited disease characterized by the clinical triad of megaloblastic anemia, sensorineural deafness, and diabetes mellitus. To date, only 100 cases of TRMA have been reported in the world. CASE PRESENTATION: Here, we describe a six-year-old boy with diabetes mellitus, anemia, and deafness. Additionally, he presented with thrombocytopenia, leukopenia, horizontal nystagmus, hepatomegaly, short stature, ventricular premature beat (VPB), and cerebral infarction. DNA sequencing revealed a novel compound heterozygous mutation in the SLC19A2 gene: (1) a duplication c.405dupA, p.Ala136Serfs*3 (heterozygous) and (2) a nucleotide deletion c.903delG p.Trp301Cysfs*13 (heterozygous). The patient was diagnosed with a typical TRMA. CONCLUSION: Novel mutations in the SLC19A2 gene have been identified, expanding the mutation spectrum of the SLC19A2 gene. For the first time, VPB and cerebral infarction have been identified in patients with TRMA syndrome, providing a new understanding of the phenotype.

Neonatal diabetes mellitus: remission induced by novel therapy.

A female child with deafness was diagnosed to have neonatal diabetes mellitus at the age of 6 months, on routine evaluation prior to cochlear implant surgery. She presented to us at 11 months of age with diabetic ketoacidosis due to an intercurrent febrile illness. Her haematological parameters showed megaloblastic anaemia and thrombocytopenia. Therefore a possibility of Thiamine Responsive Megaloblastic Anaemia (TRMA) syndrome was considered. She was empirically treated with parenteral thiamine hydrochloride (Hcl). Subsequently, due to the unavailability of pharmacological preparation of oral thiamine Hcl in a recommended dose she was treated with benfotiamine. She had a sustained improvement in all her haematological parameters on oral benfotiamine. The insulin requirement progressively reduced and she is currently in remission for last 2 years. The genetic analysis confirmed the diagnosis of TRMA syndrome. Thus benfotiamine can be considered a new treatment option in management of TRMA syndrome.

An Adult Case of Thiamine-Sensitive Megaloblastic Anemia Syndrome Accidentally Diagnosed Myelodysplastic Syndrome.

Thiamine-responsive megaloblastic anemia (TRMA) syndrome is a rare disease comprising a classic triad of megaloblastic anemia, diabetes mellitus, and early-onset sensorineural deafness. TRMA can generally be diagnosed in early childhood. Early diagnosis is important to prevent complications that may develop soon. As it is a rare disease, diagnosis may sometimes be difficult. We present a rare case of an adult patient with TRMA who had been mistakenly diagnosed with myelodysplastic syndrome (MDS), whose anemia was corrected only after thiamine treatment was started.

Genetic defects of thiamine transport and metabolism: A review of clinical phenotypes, genetics, and functional studies.

Thiamine is a crucial cofactor involved in the maintenance of carbohydrate metabolism and participates in multiple cellular metabolic processes within the cytosol, mitochondria, and peroxisomes. Currently, four genetic defects have been described causing impairment of thiamine transport and metabolism: SLC19A2 dysfunction leads to diabetes mellitus, megaloblastic anemia and sensory-neural hearing loss, whereas SLC19A3, SLC25A19, and TPK1-related disorders result in recurrent encephalopathy, basal ganglia necrosis, generalized dystonia, severe disability, and early death. In order to achieve early diagnosis and treatment, biomarkers play an important role. SLC19A3 patients present a profound decrease of free-thiamine in cerebrospinal fluid (CSF) and fibroblasts. TPK1 patients show decreased concentrations of thiamine pyrophosphate in blood and muscle. Thiamine supplementation has been shown to improve diabetes and anemia control in Rogers' syndrome patients due to SLC19A2 deficiency. In a significant number of patients with SLC19A3, thiamine improves clinical outcome and survival, and prevents further metabolic crisis. In SLC25A19 and TPK1 defects, thiamine has also led to clinical stabilization in single cases. Moreover, thiamine supplementation leads to normal concentrations of free-thiamine in the CSF of SLC19A3 patients. Herein, we present a literature review of the current knowledge of the disease including related clinical phenotypes, treatment approaches, update of pathogenic variants, as well as in vitro and in vivo functional models that provide pathogenic evidence and propose mechanisms for thiamine deficiency in humans.

Whole exome sequencing identifies a new mutation in the SLC19A2 gene leading to thiamine-responsive megaloblastic anemia in an Egyptian family.

BACKGROUND: The Solute Carrier Family 19 Member 2 (SLC19A2, OMIM *603941) encodes the thiamine transporter 1 (THTR-1) that brings thiamine (Vitamin B1) into cells. THTR-1 is the only thiamine transporter expressed in bone marrow, cochlear, and pancreatic beta cells. THTR-1 loss-of-function leads to the rare recessive genetic disease Thiamine-Responsive Megaloblastic Anemia (TRMA, OMIM #249270). METHODS: In vitro stimulated blood lymphocytes were used for cytogenetics and the isolation of genomic DNA used to perform whole exome sequencing (WES). To validate identified mutations, direct Sanger sequencing was performed following PCR amplification. RESULTS: A 6-year-old male born from a consanguineous couple presenting bone marrow failure and microcephaly was referred to our clinic for disease diagnosis. The patient presented a normal karyotype and no chromosomal fragility in response to DNA damage. WES analysis led to the identification of a new pathogenic variant in the SLC19A2 gene (c.596C>G, pSer199Ter) allowing to identify the young boy as a TRMA patient. CONCLUSION: Our analysis extend the number of inactivating mutations in SLC19A2 leading to TRMA that could guide future prenatal diagnosis for the family and follow-up for patients.

[Thiamine-responsive megaloblastic anemia or Rogers syndrome: A literature review]. / L'anémie mégaloblastique thiamine dépendante ou syndrome de Rogers : une revue de la littérature.

Thiamine-responsive megaloblastic anemia (TRMA), also known as Rogers syndrome, is a rare autosomal recessive disease characterized by three main components: megaloblastic anemia, diabetes mellitus and sensorineural deafness. Those features occur in infancy but may arise during adolescence. Diagnosis relies on uncovering genetic variations (alleles) in the SLC19A2 gene, encoding for a high affinity thiamine transporter. This transporter is essentially present in hematopoietic stem cells, pancreatic beta cells and inner ear cells, explaining the clinical manifestations of the disease. Based on a multidisciplinary approach, treatment resides on lifelong thiamine oral supplementation at pharmacological doses, which reverses anemia and may delay development of diabetes. However, thiamine supplementation does not alleviate already existing hearing defects.

A novel mutation in the SLC19A2 gene in a Turkish male with thiamine-responsive megaloblastic anemia syndrome.

Odaman-Al I, Gezdirici A, Yildiz M, Ersoy G, Aydogan G, Salcioglu Z, Tahtakesen TN, Önal H, Küçükemre-Aydin B. A novel mutation in the SLC19A2 gene in a Turkish male with thiamine-responsive megaloblastic anemia syndrome. Turk J Pediatr 2019; 61: 257-260. Thiamine-responsive megaloblastic anemia (TRMA) is a very rare syndrome characterized by the triad of early onset megaloblastic anemia, sensorineural deafness and diabetes mellitus. Here we report, a 5-year-old boy who presented with transfusion dependent anemia and diabetes mellitus and was diagnosed with TRMA. Besides reporting a novel mutation of the causative gene SLC19A2, we wanted to emphasize this syndrome in the aspect of coexistence of insulin dependent diabetes, transfusion dependent anemia and thrombocytopenia.

A novel mutation in the SLC19A2 gene in a Turkish male with thiamine-responsive megaloblastic anemia syndrome.

Odaman-Al I, Gezdirici A, Yildiz M, Ersoy G, Aydogan G, Salcioglu Z, Tahtakesen TN, Önal H, Küçükemre-Aydin B. A novel mutation in the SLC19A2 gene in a Turkish male with thiamine-responsive megaloblastic anemia syndrome. Turk J Pediatr 2019; 61: 257-260. Thiamine-responsive megaloblastic anemia (TRMA) is a very rare syndrome characterized by the triad of early onset megaloblastic anemia, sensorineural deafness and diabetes mellitus. Here we report, a 5-year-old boy who presented with transfusion dependent anemia and diabetes mellitus and was diagnosed with TRMA. Besides reporting a novel mutation of the causative gene SLC19A2, we wanted to emphasize this syndrome in the aspect of coexistence of insulin dependent diabetes, transfusion dependent anemia and thrombocytopenia.

Arrhythmia in thiamine responsive megaloblastic anemia syndrome.

Argun M, Baykan A, Hatipoglu N, Akin L, Sahin Y, Narin N, Kurtoglu S. Arrhythmia in thiamine responsive megaloblastic anemia syndrome. Turk J Pediatr 2018; 60: 348-351. Thiamine responsive megaloblastic anemia syndrome (TRMAS) is a rare, autosomal recessive disorder characterized by megaloblastic anemia, diabetes mellitus, and progressive sensorineural deafness. Mutations in the SLC19A2 gene that codes for thiamine transporter 1 protein cause TRMAS, and more than 30 homozygous mutations have been identified to date. Congenital heart diseases and arrhythmias have been reported in few patients. We present cardiac features of five patients with TRMAS. Five patients had macrocytic anemia, diabetes mellitus, and sensorineural deafness. Two siblings had also optic atrophy. SLC19A2 gene mutation was shown in all patients. Two patients developed supraventricular tachycardia during an episode of diabetic ketoacidosis. Five patients had absent P waves on baseline electrocardiography, and one patient had additional low QRS voltage. None of the patients had structural heart disease. Discontinuation of thiamine treatment appears to trigger supraventricular tachycardia episodes at puberty.

Thiamine Responsive Megaloblastic Anaemia, Diabetes Mellitus and Sensorineural Hearing Loss in a Child.

Thiamine-responsive megaloblastic anemia (TRMA) syndrome is an autosomal recessive inherited disorder characterised by a triad of megaloblastic anemia, diabetes mellitus, and sensorineural deafness. We report a case of 2-year-old girl whose anemia improved following administration of thiamine. She came with the history of persistent anaemia for the last one year. Anaemia was not responding to iron, vitamin B12, and folate replacement therapy. The bone marrow aspiration revealed hypercellular marrow with megaloblastic changes and more than 15% ring sideroblasts. The hearing assessment revealed sensorineural hearing loss. Blood sugar random and HBA1c was raised. Final diagnosis of TRMA was made. She was started on thiamine 100 mg OD, with normal routine balanced diet. She responded very well to thiamine. Her haemoglobin improved and blood sugar fasting came down in normal range. This case report sensitises the early diagnosis, and treatment with thiamine in children presenting with anemia, diabetes and deafness.

A Novel Mutation of SLC19A2 in a Chinese Zhuang Ethnic Family with Thiamine-Responsive Megaloblastic Anemia.

BACKGROUND/AIMS: Thiamine-responsive megaloblastic anemia syndrome is a rare autosomal recessive disorder resulting from mutations in SLC19A2, and is mainly characterized by megaloblastic anemia, diabetes, and progressive sensorineural hearing loss. METHODS: We study a Chinese Zhuang ethnicity family with thiamine-responsive megaloblastic anemia. The proband of the study presented with anemia and diabetes, similar to his late brother, as well as visual impairment. All clinical manifestations were corrected with thiamine (30 mg/d) supplementation for 1-3 months, except for visual impairment, which was irreversible. The presence of mutations in all exons and the flanking sequences of the SLC19A2 gene were analyzed in this family based on the proband's and his brother's clinical data. Computer analysis and prediction of the protein conformation of mutant THTR-1. The relative concentration of thiamine pyrophosphate in the proband's whole blood before and after initiation of thiamine supplement was measured by high performance liquid chromatography (HPLC). RESULTS: Gene sequencing showed a homozygous mutation in exon 6 of the SLC19A2 gene (c.1409insT) in the proband. His parents and sister were diagnosed as heterozygous carriers of the c.1409insT mutation. Computer simulation showed that the mutations caused a change in protein conformation. HPLC results suggested that the relative concentration of thiamine pyrophosphate in the proband's whole blood after thiamine supplement was significantly different (P=0.016) from that at baseline. CONCLUSIONS: This novel homozygous mutation (c.1409insT) caused the onset of thiamine-responsive megaloblastic anemia in the proband.

Pancytopenia in an adult patient with thiamine-responsive megaloblastic anaemia.

Thiamine-responsive megaloblastic anaemia (TRMA) is a syndrome associated with megaloblastic anaemia, diabetes mellitus and sensorineural deafness, due to mutations in the SLC19A2 gene, which codes for a thiamine carrier protein. Oral thiamine supplementation is the main treatment. We report the case of a 25-year-old woman known for TRMA, who presented with pancytopenia (haemoglobin 7.6 g/dL, leucocytes 2.9×109/L, thrombocytes 6×109/L) revealed by dyspnoea. Investigations excluded coagulopathy, a recent viral infection, vitamin and iron deficiencies, and a malignant process. We later found out that thiamine treatment had been discontinued 5 weeks before, due to prescription error. Parenteral thiamine administration resulted in the recovery of haematopoiesis within 3 weeks. Pancytopenia is uncommon in patients with TRMA. Pre-existing medullary impairment caused by the patient's daily antipsychotic medications or the natural course of the syndrome may explain the severity of the laboratory findings in our patient.

[Defect of thiamine transport and activation and related disease].

Thiamine, also known as vitamin B1, is an important vitamin for the body. The activated form of thiamine pyrophosphate is involved in cell metabolism as an important co-enzyme. Defects of thiamine transport and activation may cause lack of thiamine and affection of cell metabolism, leading a variety of diseases. This review has summarized defects of thiamine transport and activation and related diseases.

Pharmacogenomics in diabetes: outcomes of thiamine therapy in TRMA syndrome.

AIMS/HYPOTHESIS: Diabetes is one of the cardinal features of thiamine-responsive megaloblastic anaemia (TRMA) syndrome. Current knowledge of this rare monogenic diabetes subtype is limited. We investigated the genotype, phenotype and response to thiamine (vitamin B1) in a cohort of individuals with TRMA-related diabetes. METHODS: We studied 32 individuals with biallelic SLC19A2 mutations identified by Sanger or next generation sequencing. Clinical details were collected through a follow-up questionnaire. RESULTS: We identified 24 different mutations, of which nine are novel. The onset of the first TRMA symptom ranged from birth to 4 years (median 6 months [interquartile range, IQR 3-24]) and median age at diabetes onset was 10 months (IQR 5-27). At presentation, three individuals had isolated diabetes and 12 had asymptomatic hyperglycaemia. Follow-up data was available for 15 individuals treated with thiamine for a median 4.7 years (IQR 3-10). Four patients were able to stop insulin and seven achieved better glycaemic control on lower insulin doses. These 11 patients were significantly younger at diabetes diagnosis (p = 0.042), at genetic testing (p = 0.01) and when starting thiamine (p = 0.007) compared with the rest of the cohort. All patients treated with thiamine became transfusion-independent and adolescents achieved normal puberty. There were no additional benefits of thiamine doses >150 mg/day and no reported side effects up to 300 mg/day. CONCLUSIONS/INTERPRETATION: In TRMA syndrome, diabetes can be asymptomatic and present before the appearance of other features. Prompt recognition is essential as early treatment with thiamine can result in improved glycaemic control, with some individuals becoming insulin-independent. DATA AVAILABILITY: SLC19A2 mutation details have been deposited in the Decipher database ( https://decipher.sanger.ac.uk/ ).

Síndrome de anemia megaloblástica sensible a la tiamina de aparición en la niñez, con mutación en el genSLC19A2: caso clínico / Infantile-onset thiamine responsive megaloblastic anemia syndrome with SLC19A2 mutation: a case report

Antecedentes. El síndrome de anemia megaloblástica sensible a la tiamina (TRMA, por sus siglas en inglés), también conocido como síndrome de Rogers, se caracteriza por presentar anemia megaloblástica, hipoacusia neurosensorial y diabetes mellitus. Las alteraciones en el transporte de la tiamina hacia las células se deben a mutaciones homocigotas o heterocigotas compuestas en el gen SLC19A2. Presentación de un caso. Presentamos el caso de una niña que manifestaba sordera neurosensorial tratada con una prótesis auditiva, diabetes con necesidad de insulina y anemia macrocítica, tratada con tiamina (100 mg/día). El nivel de hemoglobina mejoró hasta alcanzar 12,1 g/dl después de aumentar la dosis terapéutica de tiamina hasta 200 mg/día. Conclusión. Se debe evaluar a los pacientes con TRMA para detectar anemia megaloblástica, hipoacusia neurosensorial y diabetes mellitus. Se les debe dar seguimiento para determinar la respuesta de la enfermedad hematológica y de la diabetes después de la terapia con tiamina. La dosis terapéutica de tiamina puede aumentarse según la respuesta clínica. Debe proporcionarse asesoramiento genético.

Background. Thiamine-responsive megaloblastic anemia syndrome (TRMA), also known as Rogers syndrome, is characterized by megaloblastic anemia, sensorineural hearing loss, and diabetes mellitus. Disturbances of the thiamine transport into the cells results from homozygous or compound heterozygous mutations in the SLC19A2 gene. Case presentation. We report a girl which presented with sensorineural deafness treated with a hearing prosthesis, insulin requiring diabetes, macrocytic anemia, treated with thiamine (100 mg/day). Hemoglobin level improved to 12.1 g/dl after dose of thiamine therapy increased up to 200 mg/day. Conclusion. Patients with TRMA must be evaluated for megaloblastic anemia, sensorineural hearing loss, and diabetes mellitus. They must be followed for response of hematologic and diabetic after thiamine therapy. It should be kept in mind that dose of thiamine therapy may be increased according to the clinical response. Genetic counseling should be given.