TRMA syndrome (thiamine-responsive megaloblastic anemia): a case report and review of the literature

Abstract: Thiamine-responsive megaloblastic anemia syndrome (TRMA) is an autosomal recessive disorder with features that include megaloblastic anemia, mild thrombocytopenia and leukopenia, sensorineural deafness and diabetes mellitus. In this disease, the active thiamine uptake into cells is disturbed. Treatment with pharmacological doses of thiamine ameliorates the megaloblastic anemia and diabetes mellitus. Previous studies have demonstrated that the disease is caused by mutations in the SLC19A2 gene encoding a high-affinity thiamine transporter. We present a 5-yr-old-boy with TRMA and, because of its rarity, we review the literature.     

Thiamine-responsive megaloblastic anaemia: a cause of syndromic diabetes in childhood

Thiamine-responsive megaloblastic anaemia (TRMA) is a rare autosomal recessive condition, characterized by megaloblastic anaemia, non-autoimmune diabetes mellitus, and sensorineural hearing loss. We describe three infants with TRMA from two consanguineous Pakistani families, who were not known to be related but originated from the same area in Pakistan. All children were homozygous, and the parents were heterozygous for a c.196G>T mutation in the SLC19A2 gene on chromosome 1q23.3, which encodes a high-affinity thiamine transporter. The result is an abnormal thiamine transportation and vitamin deficiency in the cells. Thiamine in high doses (100-200 mg/d) reversed the anaemia in all our patients. Two patients discontinued insulin treatment successfully after a short period, while the third patient had to continue with insulin. The hearing loss persisted in all three children. The diagnosis of TRMA should be suspected in patients with syndromic diabetes including hearing loss and anaemia, even if the latter is only very mild and, particularly, in the case of consanguinity.     

Thiamine-responsive megaloblastic anemia syndrome with atrial standstill: a case report

Thiamine-responsive megaloblastic anemia (TRMA) syndrome is an uncommon autosomal recessive disorder. The disease is caused by mutations in the gene, SLC19A2, encoding a high-affinity thiamine transporter, which disturbs the active thiamine uptake into cells. Major features include megaloblastic anemia, diabetes mellitus, and sensorineural deafness. Cardiac malformations with conduction defects and/or dysrhythmias, have also been described in some patients. To our knowledge, only 13 TRMA patients with cardiac defects have been reported. Here, we describe the first case of TRMA syndrome with atrial standstill, probably caused by a 2 base-pair deletion in exon 4 (1147delGT) of the gene SLC19A2.     

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

Reported here is a 2-year-old girl who was diagnosed to have thiamine-responsive megaloblastic anemia during evaluations for her bilateral neurosensorial deafness. Besides reporting a new mutation on the gene SLC19A2 for the first time in the literature, we highlight the recognition of this syndrome--when megaloblastic anemia and diabetes mellitus coexists--and the role of thiamine replacement for the treatment of both disorders.     

Recessive SLC19A2 mutations are a cause of neonatal diabetes mellitus in thiamine-responsive megaloblastic anaemia

Permanent neonatal diabetes mellitus (PNDM) is diagnosed within the first 6 months of life, and is usually monogenic in origin. Heterozygous mutations in ABCC8, KCNJ11, and INS genes account for around half of cases of PNDM; mutations in 10 further genes account for a further 10%, and the remaining 40% of cases are currently without a molecular genetic diagnosis. Thiamine-responsive megaloblastic anaemia (TRMA), due to mutations in the thiamine transporter SLC19A2, is associated with the classical clinical triad of diabetes, deafness, and megaloblastic anaemia. Diabetes in this condition is well described in infancy but has only very rarely been reported in association with neonatal diabetes. We used a combination of homozygosity mapping and evaluation of clinical information to identify cases of TRMA from our cohort of patients with PNDM. Homozygous mutations in SLC19A2 were identified in three cases in which diabetes presented in the first 6 months of life, and a further two cases in which diabetes presented between 6 and 12 months of age. We noted the presence of a significant neurological disorder in four of the five cases in our series, prompting us to examine the incidence of these and other non-classical clinical features in TRMA. From 30 cases reported in the literature, we found significant neurological deficit (stroke, focal, or generalized epilepsy) in 27%, visual system disturbance in 43%, and cardiac abnormalities in 27% of cases. TRMA should be considered in the differential diagnosis of diabetes presenting in the neonatal period.     

Cardiac Manifestations in Thiamine-Responsive Megaloblastic Anemia Syndrome

Thiamine-responsive megaloblastic anemia (TRMA) syndrome is a rare autosomal recessive disorder defined by the occurrence of megaloblastic anemia, diabetes mellitus, and sensorineural deafness, responding in varying degrees to thiamine treatment. Other features of this syndrome gradually develop. We describe three TRMA patients with heart rhythm abnormalities and structural cardiac anomalies. Eight other reported TRMA patients also had cardiac anomalies. Recently, the TRMA gene, SLC19A2, was identified, encoding a functional thiamine transporter. Characterization of the metabolic defect of TRMA may shed light on the role of thiamine in common cardiac abnormalities.     

Thiamine responsive megaloblastic anemia: a novel SLC19A2 compound heterozygous mutation in two siblings

Thiamine responsive megaloblastic anemia (TRMA) is an autosomal recessive disease caused by loss of function mutations in the SLC19A2 gene. TRMA is characterized by anemia, deafness, and diabetes. In some cases, optic atrophy or more rarely retinitis pigmentosa is noted. We now report two sisters, the eldest of which presented to a different hospital during childhood with sensorineural deafness, which was treated with a hearing prosthesis, insulin requiring diabetes, retinitis pigmentosa, optic atrophy, and macrocytic anemia. These features initially suggested a clinical diagnosis of Wolfram syndrome (WS). Therapy with thiamine was initiated which resulted in the resolution of the anemia. The younger sister, who was affected with sensorineural deafness, was referred to our hospital for non‐autoimmune diabetes. She was found to have macrocytosis and ocular abnormalities. Because a diagnosis of TRMA was suspected, therapy with insulin and thiamine was started. Sequencing analysis of the SLC19A2 gene identified a compound heterozygous mutation p.Y81X/p.L457X (c.242insA/c.1370delT) in both sisters. Non‐autoimmune diabetes associated with deafness and macrocytosis, without anemia, suggests a diagnosis of TRMA. Patients clinically diagnosed with WS with anemia and/or macrocytosis should be reevaluated for TRMA.     

Studies on thiamine metabolism in thiamine-responsive megaloblastic anaemia

We have investigated thiamine metabolism and transport in the erythrocytes of two patients from unrelated families with thamine responsive megaloblastic anaemia associated with diabetes mellitus and sensorineural deafness. Both patients had low concentrations of thiamine compounds in plasma and red blood cells. When erythrocytes were incubated with thiazole-[2-¹⁴C]-thiamine or [³⁵S]-thiamine in vitro, the concentration of label within the cells was markedly reduced compared with controls. In addition, thiamine pyrophosphokinase activity was deficient in haemolysates prepared from the patients. Some relatives of the patients showed abnormal parameters of thiamine status and transport. In both patients treatment with a lipophilic compound corrected the haematological abnormalities and diabetes and in one patient has so far prevented the progression of deafness. We propose that the disorder is caused by an inherited defect of thiamine transport, possibly related to deficient pyrophosphokinase activity, leading to intracellular depletion of active thiamine metabolite derivatives.Abbreviations TRMA thiamine-responsive megaloblastic anaemia - TMP thiamine monophosphate - TPP thiamine pyrophosphate - TPKase thiamine pyrophosphokinase - TCA trichloroacetic acid - BOM S-benzoyl-oxy-methylthiamine - RBC red blood cells - MCV mean corpuscular volume - WBC white blood cells     

Thiamine-responsive megaloblastic anemia with diabetes mellitus and sensorineural deafness

This study introduces a patient who has thiamine and thiamine pyrophosphokinase (TPKase) enzyme deficiency associated with diabetes mellitus, sensorineural deafness and thiamine-responsive megaloblastic anemia. Diabetes mellitus was diagnosed when she was 20 months old. After 1 year, macrocytic anemia developed and the thiamine therapy was started at 75 mg/day. During the follow-up, the insulin requirement decreased and even ceased, and macrocytic anemia improved with thiamine treatment. After thiamine therapy was ceased an increase in insulin requirement was observed and macrocytic anemia developed again.     

Thiamine withdrawal can lead to diabetic ketoacidosis in thiamine responsive megaloblastic anemia: report of two siblings

Thiamine responsive megaloblastic anemia syndrome (TRMA), an autosomal recessive disorder caused by the deficiency of thiamine transporter protein, is the association of diabetes mellitus, anemia and deafness. Pharmacological dose thiamine normalizes hematological abnormalities and their effects on the course of diabetes mellitus. We report on 8 years follow up of two siblings with TRMA. They presented in the prepubertal period with diabetic ketoacidosis due to lack of thiamine supplementation for 2 months. Their insulin requirements fell rapidly and disappeared with thiamine therapy. Hematological parameters normalized within 30 days. The diabetic picture is responsive to thiamine treatment in patients with TRMA. Insulin dependent diabetes may occur throughout the pubertal period. If thiamine supplementation is not sufficient, ketoacidosis may develop in patients during the prepubertal period.     

First 2 cases with thiamine‐responsive megaloblastic anemia in the Czech Republic,a rare form of monogenic diabetes mellitus: a novel mutation in the thiamine transporter SLC19A2 gene—intron 1 mutation c.204+2T>G

Thiamine‐responsive megaloblastic anemia (TRMA) is a rare autosomal recessive disorder caused by mutations in the SLC19A2 gene. To date at least 43 mutations have been reported for the gene encoding a plasma membrane thiamine transporter protein (THTR‐1). TRMA has been reported in less than 80 cases worldwide. Here, we illustrate 2 female patients with TRMA first diagnosed in the Czech Republic and in central Europe being confirmed by sequencing of the THTR‐1 gene SLC19A2. Both subjects are compound heterozygotes with 3 different mutations in the SLC19A2 gene. In case 2, the SLC19A2 intron 1 mutation c.204+2T>G has never been reported before. TRMA subjects are at risk of diabetic ketoacidosis during intercurrent disease and arrythmias. Thiamine supplementation has prevented hematological disorders over a few years in both pediatric subjects, and improved glycaemic control of diabetes mellitus. Patient 1 was suffering from hearing loss and rod‐cone dystrophy at the time of diagnosis, however, she was unresponsive to thiamine substitution. Our patient 2 developed the hearing loss despite the early thiamine substitution, however no visual disorder had developed. The novel mutation described here extends the list of SLC19A2 mutations causing TRMA.     

Thiamine-responsive anemia in DIDMOAD syndrome

Two children with the DIDMOAD syndrome (diabetes insipidus, diabetes mellitus, optic atrophy, deafness) developed a megaloblastic and sideroblastic anemia, neutropenia, and borderline thrombocytopenia. Plasma thiamine concentration was low in one patient and normal in the other; in both children, thiamine pyrophosphate in erythrocytes and thiamine pyrophosphokinase activity were lower than the lowest values observed in control subjects. A month after institution of treatment with thiamine, the hematologic findings had returned to normal and the insulin requirements had decreased. Withdrawal of thiamine repeatedly induced relapse of the anemia and an increase in insulin requirements. We propose that an inherited abnormality of thiamine metabolism is responsible for the multisystem degenerative disorder known as DIDMOAD syndrome.     

Thiamine responsive megaloblastic anemia syndrome

Thiamine responsive megaloblastic anemia syndrome (TRMA) is a clinical triad characterized by thiamine-responsive anemia, diabetes mellitus and sensorineural deafness. We report a 4-year-old girl with TRMA whose anemia improved following administration of thiamine and this case report sensitizes the early diagnosis and treatment with thiamine in children presenting with anemia, diabetes and deafness.     

Diabetes mellitus, thiamine-dependent megaloblastic anemia, and sensorineural deafness associated with deficient alpha-ketoglutarate dehydrogenase activity

Three brothers with diabetes mellitus, thiamine-responsive megaloblastic anemia, and sensorineural deafness are reported. Two had, in addition, congenital septal defects. The activities of thiamine-dependent enzymes were determined in one patient, revealing low alpha-ketoglutarate dehydrogenase activity, which could have caused a sideroblastic anemia with secondary megaloblastic changes. The anemia was thiamine dependent. The cause of the diabetes mellitus was not known, but it was not type 1.     

Incidence, genetics, and clinical phenotype of permanent neonatal diabetes mellitus in northwest Saudi Arabia

Habeb AM, Al‐Magamsi MSF, Eid IM, Ali MI, Hattersley AT, Hussain K, Ellard S. Incidence, genetics, and clinical phenotype of permanent neonatal diabetes mellitus in northwest Saudi Arabia. Background: Permanent neonatal diabetes mellitus (PNDM) in European population has an incidence of at least 1 in 260 000 live births and is most commonly due to mutations in KCNJ11 and ABCC8. However, data on this condition in other populations are limited. Objective: To define the incidence, genetic aetiology, and clinical phenotype of PNDM in Al‐Madinah region, northwest Saudi Arabia. Methods: Patients with PNDM diagnosed between 2001 and 2010 were identified and clinically phenotyped. Sequencing of KCNJ11, ABCC8, and INS were performed initially on all subjects, and EIF2AK3, GLIS3, SLC2A2, SLC19A2, GCK, IPF1, and NEUROD1 genes were sequenced according to the clinical phenotype. Results: In total, 17 patients from 11 consanguineous families were diagnosed with PNDM and the incidence was 1 in 21 196 live births. Six different mutations in four genes were identified, of which two GLIS3 and one SLC2A2 were novel and no patient had KCNJ11, ABCC8, or INS mutations. Fourteen (82.4%) patients had identifiable genetic aetiology and their PNDM was part of known autosomal‐recessive syndromes including Wolcott Rallison (41.1%), neonatal diabetes and hypothyroidism (29.4%), Fanconi‐Bickel (5.8%), and thiamine‐responsive megaloblastic anaemia (5.8%). Two patients with isolated PNDM and one with intermediate developmental delay, epilepsy and neonatal diabetes had no identifiable cause. Conclusions: Al‐Madinah region has the highest reported incidence of PNDM worldwide. In this region with high consanguinity, PNDM has different genetic aetiology and in the majority of cases presents as a part of rare familial autosomal‐recessive syndrome rather than in isolation.     

Megaloblastic anaemia in infancy or early childhood and diabetes as leading symptoms of the TRMA syndrome

Diabetes mellitus may occur in children and adolescents as an independent disease, most frequently as autoimmune type 1 diabetes, or can coexist with other abnormalities. If diabetes coincides with other disorders occurring sequentially, a syndromic form of monogenic diabetes should be suspected. Thiamine-responsive megaloblastic anaemia (TRMA) syndrome is an example of a rare form of monogenic diabetes coexisting with anaemia and deafness. In the paper, we discuss clinical features and treatment of TRMA syndrome - a unique syndromic form of vitamin-dependent monogenic diabetes. The review might be useful in establishing a prompt diagnosis and initiating optimal management in children and adolescents with the disease.     

Wolcott-Rallison syndrome: a clinical and genetic study of three children, novel mutation in EIF2AK3 and a review of the literature

Background: Wolcott-Rallison syndrome is a rare autosomal recessive condition characterized by early infancy onset diabetes mellitus and multiple epiphyseal dysplasia. So far, 17 children have been described in the world literature. Recently, mutations in the gene encoding EIF2AK3 have been shown to segregate with the syndrome in three affected families. Aims: We aimed to describe the clinical characterization and mutation analysis of a further child, and full clinical and follow-up details on our first family including the longest surviving child. Methods: Retrospective case notes review of three children presenting to the diabetic unit at our institution; mutation analysis of the EIF2AK3 gene in our most recent patient; and review of the literature on Wolcott-Rallison syndrome. Results: Previously unreported phenotypic features in our patients included developmental regression after episodes of hepatic failure, and pachygyria on brain imaging. We have identified a novel 4-base pair deletion (nt 3021-3024 del GAGA) in exon 13, which results in a frameshift and premature stop codon (R908 F/S +22X), causing premature truncation of the protein and abolition of the carboxy- segment of the catalytic domain.

Conclusions: Wolcott-Rallison syndrome causes early-onset diabetes and acute hepatic failure, before epiphyseal dysplasia is manifest. We have identified a novel mutation in EIF2AK3, and prenatal diagnosis may now be offered to affected families.     

Outpatient transition of an infant with permanent neonatal diabetes due to a KCNJ11 activating mutation from subcutaneous insulin to oral glyburide

Abstract:  Neonatal diabetes mellitus is rare, may either be transient or permanent, and may be caused by mutations in any of the several different genes. Until recently, most forms of permanent neonatal diabetes required lifelong subcutaneous insulin for management; however, permanent neonatal diabetes due to activating mutations in the KCNJ11 gene, which encodes the Kir6.2 protein subunit of the ATP-sensitive K⁺ (K_ATP) channel, may be amenable to oral sulfonylurea therapy. We describe a case of an 18-month-old infant with permanent neonatal diabetes due to an activating KCNJ11 mutation successfully transitioned from subcutaneous insulin therapy to oral sulfonylurea therapy in the outpatient setting.     

Two Japanese infants with congenital generalized lipodystrophy due to BSCL2 mutations

Background: Congenital generalized lipodystrophy (CGL), Berardinelli‐Seip syndrome, is a rare autosomal recessive disorder characterized by the generalized absence of adipose tissue at birth, severe insulin resistance early in life, hypertriglyceridemia, hepatomegaly, and the development of diabetes mellitus during puberty. Recently, two genes, BSCL2 and AGPAT2, were identified as causative genes for CGL. It has been reported that patients with BSCL mutations present with more severe clinical findings than those with AGPAT2 mutations. However, the clinical course of CGL caused by BSCL2 mutations in infancy has not been fully elucidated. Methods: Two Japanese infantile patients with CGL from independent families were examined and underwent an oral glucose tolerance test. Insulin resistance and insulin secretion were estimated using the homeostasis model assessment for insulin resistance and the insulinogenic index, respectively. Sequence analysis of the entire coding region of BSCL2 and AGPAT2 was performed. Results: Both CGL patients presented with normal glycemic profiles after oral glucose tolerance tests; however, the values from the homeostasis model assessment of insulin resistance were elevated and well above the cut‐off point for diagnosis of infant insulin resistance in both patients. One patient possessed a known homozygous nonsense mutation in exon 8 (c.823C>T) of BSCL2; the other had a novel homozygous missense mutation in exon 5 (c.560A>G) of BSCL2. Conclusion: Japanese CGL patients with BSCL2 mutations presented with severe insulin resistance, even during infancy, prior to the development of diabetes mellitus.     

Prevalence of germline mutations in the TSH receptor gene as a cause of juvenile thyrotoxicosis

Aim: To ascertain the prevalence of germline mutations in the TSH receptor gene as a cause of juvenile thyrotoxicosis (JT) in non-autoimmune patients. TSH receptor gene mutations are not seen in autoimmune-active patients. Methods: In a nationwide study on JT, 123 patients were re-examined 10 y (range 4 to 21 y) after diagnosis. Two patients with toxic adenoma were excluded. In 25 patients, no TPO, TG or TSH-R antibodies were found. In 17 patients, DNA material was available for TSH receptor gene analysis. The entire TSH receptor gene was sequenced in five patients. TSH receptor “hot spots” for mutations in exon 9 and 10 were sequenced in the remaining 12 patients. Results: A TSH receptor gene germline mutation was identified in only one patient of a total number of 121 patients with JT, of which 17 patients were presumed to have non-autoimmune JT by the lack of thyroid autoantibodies.

Conclusion: In Denmark the prevalence of germline mutations in the TSH receptor gene is one in 121 patients with JT (0.8%; 95% CI: 0.02-4.6%) and one in 17 patients with presumed non-autoimmune JT (6%; 95% CI: 5.88% (0.15-28.69)).