Résumé
Thiamine responsive megaloblastic anemia syndrome is a rare autosomal recessive disorder defined by the occurrence of megaloblastic anemia, diabetes mellitus, and neurosensoriel deafness, responding in varying degrees to thiamine treatment. Report an unusual case of this rare disorder. We report the case of a four-year-old boy who presented unusual features of thiamine- responsive megaloblastic anemia. In addition to the typical triad of the syndrome, he presented leuconeutropenia, hepatosplenomegalia, cardiac abnormalities including absent P waves, mitral and tricuspid insufficiency, retinitis pigmentosa, nystagmus, developmental delay and a brain Magnetic resonance imaging ischemic lesion. Lactate levels in serum and the lactate/ pyruvate ratio were increased. The mitochondrial mutation m.3243A > G located in MTTL1 gene encoding for transfer RNA leucine [tRNALeu[UUR]] was not found. Treatment with thiamine resulted in normalisation of the haemoglobin level, white cell count, and glucose and lactate levels. On three years follow up, the patient did not need insulinotherapy. These data sign the crucial role that thiamine plays for many cells and tissues and its importance in the activity of the respiratory chain